4l60e first gear issue after warm up

hollywood6964

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Feb 13, 2022
29
Glendale
So I bought a 08 silverado recently, don't want to get into the story......Anyways, I personally think the vehicle was overheated shortly before I got it. Let's put that aside for min and go off what I know for sure.

The trans was rebuilt about 49k ago, shop that did it says it was stamped on there (so previous owner was truthful about that).
Fluid was not changed as of yet. Looks red, but imo smells a touch burnt.
Fluid was maybe 3/4 quart low when I got it.
When warms up to about 150 or so, it starts the problem and progressively gets worse as it warms further to about 175 (far as I warm it typically).
Problem is when stopped, or put into D, or even 1, it will hang n float, like it's not fully engaged into first gear, then I tap the gas a bit, and it drops into gear w a bit of a thud (if Ilet it do it by itself, it eventually will, sometimes you'll feel the engagement fully, almost like it was just shifted into D). All other gears work fine, including starting in 2nd, or R, no float n thud. 4th is fine as well.


Now the shop is pretty damn good, used them in the past and they have a great rep here, but they thought the problem was the engine mount at first (although I knew better), so I replaced the D side mount n trans mount, and of course problem stayed the same. After that they of course said yeah, trans issue. They looked into it, got back to me from transgo's advice, and said that it could be one of the shift solenoids doing that (no codes if wondering). The guy's been doing this for about 35 years and really seemed stumped by the issue and how it felt to him, I thought it was pretty obvious, but whatever. I don't think the solenoid will do much of anything, but I don't see why not to change it, cheap enough.

Anyone have any further advice on this? Maybe not just an a-b solenoid, possibly the 3-2, or Torque Converter solenoid or pressure control solenoid? Thus far I've bought a couple gm a-b shift solenoids, some delco trans fluid and mt-10 additive (which I will add 2nd, if the solenoids don't do anything).
 

mrrsm

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These are the GM ATSG 4l60E-4l80E Transmission Diagnostics and Repair "Bibles" worth Downloading into a Folder and then referred to often for access to the "Professional OEM Straight Skinny" . They will have most of the Answers to your Questions with a non-anecdotal flavor:
 

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hollywood6964

Original poster
Member
Feb 13, 2022
29
Glendale
These are the GM ATSG 4l60E-4l80E Transmission Diagnostics and Repair "Bibles" worth Downloading into a Folder and then referred to often for access to the "Professional OEM Straight Skinny" . They will have most of the Answers to your Questions with a non-anecdotal flavor:
appreciate it.
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
While there, I'd try swapping the solenoids.

To me, it sounds like a pressure problem somewhere because as it warms up, the fluid looses viscosity (or thickness) and the pressure drops. And the fact it will drop into gear with some more RPM to increase the pressure kinda confirms that. Did the shop check the pump's pressure output? That should be pretty standard practice for a transmission shop.

If I were shotgunning this, I would replace the solenoids, drop the valve body and put in a shift kit with new VB plate and pressure regulator that comes with the kit. I'm not super techie on trannys but if there is a leaky accumulator, regulator or solenoid, this would take care of it. Mechanically the tranny should be fine, it's a pressure issue somewhere. Ask the shop if they put in a shift kit already.
 

hollywood6964

Original poster
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Feb 13, 2022
29
Glendale
While there, I'd try swapping the solenoids.

To me, it sounds like a pressure problem somewhere because as it warms up, the fluid looses viscosity (or thickness) and the pressure drops. And the fact it will drop into gear with some more RPM to increase the pressure kinda confirms that. Did the shop check the pump's pressure output? That should be pretty standard practice for a transmission shop.

If I were shotgunning this, I would replace the solenoids, drop the valve body and put in a shift kit with new VB plate and pressure regulator that comes with the kit. I'm not super techie on trannys but if there is a leaky accumulator, regulator or solenoid, this would take care of it. Mechanically the tranny should be fine, it's a pressure issue somewhere. Ask the shop if they put in a shift kit already.
So I just dropped the pan. Found what looks like a pebble in there. I'll take a picture and upload. Not looking good. Also the way the gasket is shot, I'm doubting it was rebuilt at that shop, they may have just replaced all of the solenoids, as I can see the pick marks where they were trying to get to the pins on the Torque Converter solenoid and pressure control solenoid.

The shop did say it was stamped under there, but they couldn't find his name. Usually any service would be documented, but if it were just a full solenoid service, I wouldn't be surprised if they just receipted him, and he just lied about the rebuild. I do know the valve body is not new at least because of the picks (have pics of the valve body I'll upload), of course they could've reused it n those marks could be old. However, that gasket is shot, and was stuck to the the trans, n not the pan......

Either way, I'm replacing a n b solenoid. I probably should've replaced all 5, but the shop was talking the shift solenoid, and wasn't talking 3-2, tc or pressure control. Now that I'm thinking of it, pressure control might not be a bad idea, if the pressure is poor, this might be an issue. BUT, that pebble, is not a good sign overall. Outside of that, it looked like normal metal buildup around the magnet, maybe some minor flaking at the bottom.
 
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hollywood6964

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Feb 13, 2022
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Glendale
Here's the bottom of the pan w the pebble in the corner. Could i guess be possible it got knocked in from the bottom of the truck or whatever when I pulled it. But it's a rock, not metal. Outside of that, looked ok. I only had a gallon of atf so now im waiting for amazons delivery tonight of another gal. Im sure i only need about a quart and a half, but i may have to drop the pan again n im not risking it to drive.

We shall see if there's any difference. I doubt it. If anything the mt10 i will put in after there's no change might help temporarily.
 

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Mooseman

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Dec 4, 2011
25,257
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Maybe the PO did it in his gravel driveway :blinkhuh:

The stuff on the magnet doesn't look excessive. Use a new filter just in case it was never replaced. Have seen shifting issues caused by plugged filters.
 

hollywood6964

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Feb 13, 2022
29
Glendale
Maybe the PO did it in his gravel driveway :blinkhuh:

The stuff on the magnet doesn't look excessive. Use a new filter just in case it was never replaced. Have seen shifting issues caused by plugged filters.
I replaced the filter. I kind of smeared the metal magnet before the pic, that's why it's like that. I'm going to post a pic of the old a b solenoids from my phone in a min. Is that pressure control solenoid easy to replace, I know it's right there but is there anything special holding it back?
 

hollywood6964

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Feb 13, 2022
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Here's a look at the valve body as well. I have a couple of close up shots of one half n the other w proper lighting if there's anything you might see from that.
 

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Mooseman

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Dec 4, 2011
25,257
Ottawa, ON
It's not a solenoid, it's a valve held in my a snap ring. Haven't heard of these failing before. I wouldn't much around with it. I can't tell anything from the solenoids. I don't even know which is which. I'd replace them all in case one is leaky.
 

hollywood6964

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Feb 13, 2022
29
Glendale
It's not a solenoid, it's a valve held in my a snap ring. Haven't heard of these failing before. I wouldn't much around with it. I can't tell anything from the solenoids. I don't even know which is which. I'd replace them all in case one is leaky.
They're just the 1-2 n 3-4s. If this doesn't work, next is to take it apart again n replace the 3-2 n tcc solenoid. What I was talking about in a solenoid, is gm#

24248893​


it's listed as

Automatic Transmission Pressure Control Solenoid Valve​


That's what I'm thinking in hindsight when you said I might have a pressure issue. Of course the valve body could have been reused and is now failing. 174k and allegedly the trans was rebuilt at 125.
 

hollywood6964

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Feb 13, 2022
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Glendale
Well that didn't do anything. I put in the mt-10 as a hail mary n see if it does anything. Maybe replace the pressure control solenoid when I can drop the pan again. If anyone has any other ideas, I'm all ears. (I think clutch packs or sprag is going)
 

Mooseman

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Dec 4, 2011
25,257
Ottawa, ON
OK, did some google-fu and did find something similar to yours.


if you have 2nd 3rd and 4th automatically and do notdownshift to first there are only a few possibilites in this order
1-2nd accumulator piston broke
2-The PCM is not comanding first
3-The spring for the 1-2 shift valve is broken .

Its not likley a solenoid since 1st and 4th use the same solenoid, Now if you told me you had 2nd 3rd and lockup but no 1st or 4th ? I would say shift solenoid A

When the accumulator breaks it allows modulated oil from the back side of the piston to leak through and apply the band causing a second start, But ussuallly not at max line. If this is the case you will eventually burn up the band and or the 3-4 clutch pack.
There could be some reason the PCM does not comand 1st. To determine this you would need to hook up to a scanner and see what gears being comanded.

Look for witness marks on the bellhousing bolts indicating that the tranny has been removed before for a rebuild or replacement. Same on the inside on the valve body.

As it says above, I could see a leaky accumulator causing this. There aren't too may out there with first gear only failures. I don't see why the PCM wouldn't command first gear unless it thinks you're asking for second gear but cold seems to so it doesn't look like it.
 

hollywood6964

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Feb 13, 2022
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Glendale
OK, did some google-fu and did find something similar to yours.




Look for witness marks on the bellhousing bolts indicating that the tranny has been removed before for a rebuild or replacement. Same on the inside on the valve body.

As it says above, I could see a leaky accumulator causing this. There aren't too may out there with first gear only failures. I don't see why the PCM wouldn't command first gear unless it thinks you're asking for second gear but cold seems to so it doesn't look like it.
Not sure if I'm reading that right, but mine will downshift just fine. Read the thread, seems different. I'm not getting that type of pressure. But still could apply to an extent.
Cold shifts are a bit rough to be sure, until the temp goes over 95 or 100, then it's normal.
In fact it gets better as it warms, besides the first gear at a stop or a shift into 1st or D.

I've driven w bad trannys before, and this works here as well. If I have the temps up, and I come to a stop very gently, w just enough brake pressure to stop the vehicle, just barely, and never fully depress the brake, a lot of times it will not slip out first, it'll hold. Take that same scenario, and I have to stop quickly- it will for sure slip out of gear into neutral and require a nudge. Hell even just stop normal, and it'll need a slight bump.

One other thing, I could be wrong, but I think a few of the valve body bolts were leaking when I had the pan out for a while yesterday. I kept seeing fluid accumulate around bolts, now I could be wrong, and it could've been fluid running down from channels etc., but I took a close look, and I'd lean towards that. I may have pics on the close ups I took where it illustrates it.
 

hollywood6964

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Feb 13, 2022
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Glendale
There's one bolt that seems pretty obvious it is leaking. I had already wiped down everything multiple times n the pan was down for well over an hour at that point. There were a couple others, but in the pics this was the most evident.
 

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Mooseman

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Dec 4, 2011
25,257
Ottawa, ON
Cold shifts are a bit rough to be sure, until the temp goes over 95 or 100, then it's normal.
In fact it gets better as it warms, besides the first gear at a stop or a shift into 1st or D.
Then I read your first post wrong. Thought it got worse as it got warm and would slip or not engage in first gear. Could still be the accumulator. I would think that a good tranny shop should be able to diagnose this. It could very well be a problem with the VB which they should be able to easily fix.

Same here whenever I take the pan down. I wipe off as much of the oil as I can and it keeps coming from various bolts and other places.
 

hollywood6964

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Feb 13, 2022
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Glendale
Then I read your first post wrong. Thought it got worse as it got warm and would slip or not engage in first gear. Could still be the accumulator. I would think that a good tranny shop should be able to diagnose this. It could very well be a problem with the VB which they should be able to easily fix.

Same here whenever I take the pan down. I wipe off as much of the oil as I can and it keeps coming from various bolts and other places.
No you didn't read it wrong. All other shifting options besides first at a stop or being shifted into from p n or r is great when warmed up.

Im going to get the forward accumulator piston n pin, and 1/2 accumulator kit and the pressure control solenoid n go after it again this weekend. Use the same fluid of course. I am half thinking am entire rebuilt valve body, but that's only necessary if the forward accumulator hole is bored out. Sleep on it.
 
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hollywood6964

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Then I read your first post wrong. Thought it got worse as it got warm and would slip or not engage in first gear. Could still be the accumulator. I would think that a good tranny shop should be able to diagnose this. It could very well be a problem with the VB which they should be able to easily fix.

Same here whenever I take the pan down. I wipe off as much of the oil as I can and it keeps coming from various bolts and other places.
Talked to the trans shop owner. He doesnt think its the forward accumulator. Since i can start off the line in second when warm w no slip. That makes sense since it's always enacted. Still think its a clutch that's burned up. He said his shop replaces it w the aluminum one, n if it was rebuilt by them it'd be in there.
 

Reprise

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Coming in late here, but based on what I've read, I'd agree that I'd look at the 1st clutch or the forward sprag. I also thought the forward accum could perhaps be in play (but if it were rebuilt, a new o-ring would have been used (IIRC, they do have an o-ring; it's been a few years for me).

FYI... When I put the shift kit in my Envoy's 4L60e (a 2003), the OEM fwd accumulator piston *was* aluminum (as was the 1-2 accumulator; the 4th accumulator was the only plastic one in the valve body). They do have a guide / centering pin, which can wear (but again, if the thing had been fully rebuilt, they'd have noted the play, if it were worn, and replaced the assembly). GM did use more plastic as the years went on, so your '08 could very well have had all plastic accumulators (hope not!)

I did convert to the Sonnax pinless for the forward and 1-2 accumulators, as they were in my kit, and moved the OEM 1-2 piston to the 4th accumulator (they're the same size / interchangeable), as I figured it was better than plastic (although there's a school of thought that as soft as the pressure is in the 4th accum, you could probably have *no* piston in there whatsoever, and it would operate the same. But I digress).

The same goes for the clutches -- you'd never rebuild a trans without replacing them, IMO, even if they weren't 'worn'. And you didn't find any gritty clutch residue in the pan, so there's that, too. If the rebuilder used upgraded clutches, even less likely they'd wear (btw, the 3rd clutch is the weakest of them; you'll usually lose that one first (and if so, no 2-3 shift, which is *not* your problem).

That leaves the sprag (aka: 'roller clutch', or 'forward drive clutch'), which is a known weak item (improved ones exist, but an 'absolutely bulletproof' one doesn't (for the 4L60, anyway)).
I did note what you said about the issue not being present if you were doing a rolling-type stop, etc. Another strike against the sprag, IMHO.

Note that I'm not a professional mech / trans rebuilder; I just take an interest in them, same as I do with the rest of the driveline. So I'd put more stock in what a professional tells you. But I do think you're thinking 'correctly' as to your issue.

BTW... the 1-2 and 3-4 shift solenoids are interchangeable, so one way of testing them is to swap them and see if the issue moves to the other gear. I *don't* think they'll make a bit of difference for you; that's just 'fyi'.
Also, the pressure control solenoid (aka: 'force motor') does have an adjustment screw, that can increase line pressure. Again, only 'fyi', as the better way to increase line pressure is via PCM programming. Some early F-body owners (with SBCs and no PCM) do adjust the screw - but only by 1/4 turn -- no more.
 
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hollywood6964

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Coming in late here, but based on what I've read, I'd agree that I'd look at the 1st clutch or the forward sprag. I also thought the forward accum could perhaps be in play (but if it were rebuilt, a new o-ring would have been used (IIRC, they do have an o-ring; it's been a few years for me).

FYI... When I put the shift kit in my Envoy's 4L60e (a 2003), the OEM fwd accumulator piston *was* aluminum (as was the 1-2 accumulator; the 4th accumulator was the only plastic one in the valve body). They do have a guide / centering pin, which can wear (but again, if the thing had been fully rebuilt, they'd have noted the play, if it were worn, and replaced the assembly). GM did use more plastic as the years went on, so your '08 could very well have had all plastic accumulators (hope not!)

I did convert to the Sonnax pinless for the forward and 1-2 accumulators, as they were in my kit, and moved the OEM 1-2 piston to the 4th accumulator (they're the same size / interchangeable), as I figured it was better than plastic (although there's a school of thought that as soft as the pressure is in the 4th accum, you could probably have *no* piston in there whatsoever, and it would operate the same. But I digress).

The same goes for the clutches -- you'd never rebuild a trans without replacing them, IMO, even if they weren't 'worn'. And you didn't find any gritty clutch residue in the pan, so there's that, too. If the rebuilder used upgraded clutches, even less likely they'd wear (btw, the 3rd clutch is the weakest of them; you'll usually lose that one first (and if so, no 2-3 shift, which is *not* your problem).

That leaves the sprag (aka: 'roller clutch', or 'forward drive clutch'), which is a known weak item (improved ones exist, but an 'absolutely bulletproof' one doesn't (for the 4L60, anyway)).
I did note what you said about the issue not being present if you were doing a rolling-type stop, etc. Another strike against the sprag, IMHO.

Note that I'm not a professional mech / trans rebuilder; I just take an interest in them, same as I do with the rest of the driveline. So I'd put more stock in what a professional tells you. But I do think you're thinking 'correctly' as to your issue.

BTW... the 1-2 and 3-4 shift solenoids are interchangeable, so one way of testing them is to swap them and see if the issue moves to the other gear. I *don't* think they'll make a bit of difference for you; that's just 'fyi'.
Also, the pressure control solenoid (aka: 'force motor') does have an adjustment screw, that can increase line pressure. Again, only 'fyi', as the better way to increase line pressure is via PCM programming. Some early F-body owners (with SBCs and no PCM) do adjust the screw - but only by 1/4 turn -- no more.
So I've thought about that, the adjustment. Might override the issue for a while, might not. Also yeah I know, 1/2 n 2/3 solenoid are the same, I did replace those, no change, as I suspected (that was the trans shop owner suggesting, from transgo. Owner said if they rebuilt it, they replace the plastic garbage w aluminum, so the forward accumulator could not be an issue, neither 1/2 accum. Also because it doesn't have the problem starting in second, he thinks it wouldn't be the forward accum, because I'd have the same issue even starting in second. Could be debatable.

Now, another thing, the forward abuse valve might be a problem, or the boost valve. Can be an issue with old worn out valve bodies. Doubt the builder used sonnax, which make slightly oversized n stout fittings, where as transgo are good, but not really made for worn valve bodies like sonnax can be used for. I wouldn't be surprised if the valve body is just worn, and either the sonnax will help a fair bit, or completely for a while, or if I just need to pull the VB and install a new one. Not something I'm looking forward too, with all the greasing on the check balls trying to hold them in place, and the plate n papers, n trying to get it on while on my back under the damn truck.

I also wouldn't be surprised if a new valve body would solve the root cause, but the damage has been done to the first gear clutch or sprag, and it doesn't help the issue for very long, or at all.

The original owner told me when he did the rebuild w them, he just lost first gear completely at a stop light. Sound familiar? I'm guessing that valve body was already worn w the plastic parts(lot of plastic in 08), and maybe had a lead foot, and when they replaced the part n rebuilt the valve, it covered up the wear for a while, but eventually it showed through. I'm guessing transgo parts, which are fine, but not sonnax, like I said, made for worn VB's (although it may be too late for even those).
 
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Reprise

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Not something I'm looking forward too, with all the greasing on the check balls trying to hold them in place, and the plate n papers, n trying to get it on while on my back under the damn truck.
Just a quick reply on this... it's really not too bad (it's how I did mine, as I don't have a lift)

Medium tack transjel (or even Vaseline!) will keep things in place. Use some of the bolts as a jig to put the gaskets in place (the plate bolts in).

Depending on how much vaseline you use, and how quickly you start driving after assembly, it'll shift a little harder for about 10min, until the vaseline melts from the heat of the fluid and lets the checkballs move freely. But it's not bad at all -- get your plate / gaskets set up, use a little dab of vaseline / jel to keep the gaskets in place as needed, dose up the checkball locations, and have at it. Maybe put a blue shop towel or two down, if you're worried about crawling under with VB in hand.

Not suggesting the VB is the cure for your issues... just that it's not really that much of a pain to put it back together on the ground. A garage helps, to be sure. And, yeah, I was about 5yrs younger than I am now, when I did it. But I'd do it again.

I'm actually thinking about dragging out my 4L80 out of the Sierra and rebuilding it (preventative maintenance; it's got 250K on it). And the truck will be on jackstands (see: "I don't have a lift", above).
 

hollywood6964

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Just a quick reply on this... it's really not too bad (it's how I did mine, as I don't have a lift)

Medium tack transjel (or even Vaseline!) will keep things in place. Use some of the bolts as a jig to put the gaskets in place (the plate bolts in).

Depending on how much vaseline you use, and how quickly you start driving after assembly, it'll shift a little harder for about 10min, until the vaseline melts from the heat of the fluid and lets the checkballs move freely. But it's not bad at all -- get your plate / gaskets set up, use a little dab of vaseline / jel to keep the gaskets in place as needed, dose up the checkball locations, and have at it. Maybe put a blue shop towel or two down, if you're worried about crawling under with VB in hand.

Not suggesting the VB is the cure for your issues... just that it's not really that much of a pain to put it back together on the ground. A garage helps, to be sure. And, yeah, I was about 5yrs younger than I am now, when I did it. But I'd do it again.

I'm actually thinking about dragging out my 4L80 out of the Sierra and rebuilding it (preventative maintenance; it's got 250K on it). And the truck will be on jackstands (see: "I don't have a lift", above).
Yeah im think of putting it on stands if i have too. Im deliberating what to replace right now. I have to do this soon, if im going to, as it gets warmer here in az, its going to show the problem more n more. The previous owner of course could have. Been lying, n the shop couldve made a mistake. So id like to at least turn over that stone before throwing in the towel. I dont think im experienced enough to take the trans down n replace the pumps boost valve, although im not far off from giving it a go if the forward abuse and forward accumulator doesnt work. Trying to get my ducks in a row before frigging w the vb again.
 

hollywood6964

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Did the line pressure test, when I'm not having the problem, never goes below about 60ish psi in idle, meets the 55psi minimum. When I'm having the problem, it hits about 45psi in D, then I have to tap the gas just a hair and it rapidly goes to around 65psi.

I unfortunately have the model where the turbine speed sensor seems to be in the way of the boost valve, at least in my photo, the pigtail is in the way. Any work around, or does the pump need to come out/transmission removed from engine?

Also, is that the likely culprit? Seems to be the common denominator. How about the pressure regulator valve that resides in the same hole? Anyone had to replace the entire pump cover because the hole was bored out?

Probably some questions as I go, trying to get my ducks in a row before tearing this thing apart.
 

hollywood6964

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Feb 13, 2022
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Glendale
Coming in late here, but based on what I've read, I'd agree that I'd look at the 1st clutch or the forward sprag. I also thought the forward accum could perhaps be in play (but if it were rebuilt, a new o-ring would have been used (IIRC, they do have an o-ring; it's been a few years for me).

FYI... When I put the shift kit in my Envoy's 4L60e (a 2003), the OEM fwd accumulator piston *was* aluminum (as was the 1-2 accumulator; the 4th accumulator was the only plastic one in the valve body). They do have a guide / centering pin, which can wear (but again, if the thing had been fully rebuilt, they'd have noted the play, if it were worn, and replaced the assembly). GM did use more plastic as the years went on, so your '08 could very well have had all plastic accumulators (hope not!)

I did convert to the Sonnax pinless for the forward and 1-2 accumulators, as they were in my kit, and moved the OEM 1-2 piston to the 4th accumulator (they're the same size / interchangeable), as I figured it was better than plastic (although there's a school of thought that as soft as the pressure is in the 4th accum, you could probably have *no* piston in there whatsoever, and it would operate the same. But I digress).

The same goes for the clutches -- you'd never rebuild a trans without replacing them, IMO, even if they weren't 'worn'. And you didn't find any gritty clutch residue in the pan, so there's that, too. If the rebuilder used upgraded clutches, even less likely they'd wear (btw, the 3rd clutch is the weakest of them; you'll usually lose that one first (and if so, no 2-3 shift, which is *not* your problem).

That leaves the sprag (aka: 'roller clutch', or 'forward drive clutch'), which is a known weak item (improved ones exist, but an 'absolutely bulletproof' one doesn't (for the 4L60, anyway)).
I did note what you said about the issue not being present if you were doing a rolling-type stop, etc. Another strike against the sprag, IMHO.

Note that I'm not a professional mech / trans rebuilder; I just take an interest in them, same as I do with the rest of the driveline. So I'd put more stock in what a professional tells you. But I do think you're thinking 'correctly' as to your issue.

BTW... the 1-2 and 3-4 shift solenoids are interchangeable, so one way of testing them is to swap them and see if the issue moves to the other gear. I *don't* think they'll make a bit of difference for you; that's just 'fyi'.
Also, the pressure control solenoid (aka: 'force motor') does have an adjustment screw, that can increase line pressure. Again, only 'fyi', as the better way to increase line pressure is via PCM programming. Some early F-body owners (with SBCs and no PCM) do adjust the screw - but only by 1/4 turn -- no more.
So I have line pressure issues, you can see in my last post. 70ish actually when all is well at idle then 46 when the problem arises. Im thinking the pump is worn at the bore holes for the valves. I ordered a sonnax tcc valve n transgo boost .472 and drop in transgo pr valve to use the unworn parts of the pump bore. thinking long n hard about buying a refurbished pump assembly to put the valves in, mainly because i have to remove the pump to get to the valves because the speed sensor is in the way on the 08s.
 
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Reprise

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I unfortunately have the model where the turbine speed sensor seems to be in the way of the boost valve, at least in my photo, the pigtail is in the way. Any work around, or does the pump need to come out/transmission removed from engine?

Also, is that the likely culprit? Seems to be the common denominator. How about the pressure regulator valve that resides in the same hole? Anyone had to replace the entire pump cover because the hole was bored out?
AFAIK, the boost valve (in the pump) is in the same location, all years.
Here's a pic of it, for reference (note the shift lever / park pawl beside it)...
1645562608024.png
Now... that said... while it's technically removable with the trans in-truck, it is VERY difficult to remove (and I'll say right now that I couldn't, with the tools I had at the time, 5-6yrs ago)

You'll need a pair of snap ring pliers with a long nose, and slender besides.
Also, the valve is putting pressure on that ring due to what's behind it, so what you want to do is push up on it to relieve pressure on the snap ring, while at the same time, removing the snap ring. Then be ready to keep pressure on it while you back it out; there's a valve and spring assembly behind it. So it's a two-handed operation, and the one hand better be dexterous with the pliers. All the while, you're doing this on your back, with limited room.

I ordered a sonnax tcc valve n transgo boost .472 and drop in transgo pr valve to use the unworn parts of the pump bore. thinking long n hard about buying a refurbished pump assembly to put the valves in, mainly because i have to remove the pump to get to the valves because the speed sensor is in the way on the 08s.
That doesn't sound right to me -- the TCC valve is within the valve body assembly, and shouldn't need the pump to be pulled. Remember that you need the reaming kit to install the Sonnax valve. You have to ream the opening in the VB (with great care), sleeve the opening, and then install the TCC valve. It's considered the better fix vs. the TransGo solution (new valve / springs, no reaming), but if the bore isn't worn, I'd put the TransGo assembly in -- many here have, and it's lasted a long time, as the movement of that valve converts to a straight 'on / off', vs. the constant PWM cycling that it does, stock). Kind of makes things feel like a '5th gear', when it goes into lockup.

However, if the TCC valve bore *is* worn, then you either need the Sonnax kit, or a new VB (and if you're going this route, get one from a vendor that has already installed the better Sonnax solution in the reman'd body). It'll cost a little more, but it'll be done. Note that the Sonnax retains PWM movement (the sleeve is steel, so bore wear due to movement is eliminated). If you like PWM, go with Sonnax. If you'd rather get rid of PWM modulation, TransGo's solution works better (and like I mentioned, it's way easier to install, provided the bore isn't worn (if you can 'jiggle' the valve at all in the housing, it's worn).

The pump isn't *too* hard to replace, but the trans *does* need to be disconnected from the engine and moved back (or removed outright) -- it's right behind the torque converter.

If you go as far as replacing the pump...
- Give some thought to putting in a new torque converter; you're there anyway, and they do go bad.
- There are 10-vane (OEM) and 13-vane pumps. The 13-vanes are supposed to be HD, but the 10-vanes are just fine for most applications. I wouldn't worry about beefing up the pump assembly.
- Pumps go bad, but they can last a long time before they blow up. Usually, you'll hear a whine from them, but they can literally last years after the whining starts.
- If you're going after the pump, you're in a good place to do the full rebuild, if you're in for replacing the clutch packs, etc. This is where you *do* get the beefed up parts -- clutches, sunshell, etc., etc.
- After the new pump is installed, and you're going to reinstall the torque converter (new or existing)... remember there are THREE seating actions, and all three must occur, or you'll destroy the pump on the first start. Also, if it's not fully seated, there usually won't be enough clearance between the TC and flexplate, when you put the trans in position to reattach them together. So make sure it's fully seated.

Finally, if you're putting in a new converter, it's good practice to pour a quart of fluid into it, prior to installing it into the pump -- otherwise, it runs dry on startup, and has to wait several seconds for fluid to fill it. Same thing if you're reusing the old converter -- drain / replace the fluid from it, before reinstall.

- You can reuse the TC <> flexplate bolts, but it's good practice to get new ones.

If you remove the flexplate (like to do the rear main seal, 'since you're there')... be SURE to replace the flexplate <> crank bolts with new ones, and also use threadlocker (I think medium / blue is the right strength, but double-check).

I hope this helps a bit.
 

hollywood6964

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AFAIK, the boost valve (in the pump) is in the same location, all years.
Here's a pic of it, for reference (note the shift lever / park pawl beside it)...
View attachment 103085
Now... that said... while it's technically removable with the trans in-truck, it is VERY difficult to remove (and I'll say right now that I couldn't, with the tools I had at the time, 5-6yrs ago)

You'll need a pair of snap ring pliers with a long nose, and slender besides.
Also, the valve is putting pressure on that ring due to what's behind it, so what you want to do is push up on it to relieve pressure on the snap ring, while at the same time, removing the snap ring. Then be ready to keep pressure on it while you back it out; there's a valve and spring assembly behind it. So it's a two-handed operation, and the one hand better be dexterous with the pliers. All the while, you're doing this on your back, with limited room.


That doesn't sound right to me -- the TCC valve is within the valve body assembly, and shouldn't need the pump to be pulled. Remember that you need the reaming kit to install the Sonnax valve. You have to ream the opening in the VB (with great care), sleeve the opening, and then install the TCC valve. It's considered the better fix vs. the TransGo solution (new valve / springs, no reaming), but if the bore isn't worn, I'd put the TransGo assembly in -- many here have, and it's lasted a long time, as the movement of that valve converts to a straight 'on / off', vs. the constant PWM cycling that it does, stock). Kind of makes things feel like a '5th gear', when it goes into lockup.

However, if the TCC valve bore *is* worn, then you either need the Sonnax kit, or a new VB (and if you're going this route, get one from a vendor that has already installed the better Sonnax solution in the reman'd body). It'll cost a little more, but it'll be done. Note that the Sonnax retains PWM movement (the sleeve is steel, so bore wear due to movement is eliminated). If you like PWM, go with Sonnax. If you'd rather get rid of PWM modulation, TransGo's solution works better (and like I mentioned, it's way easier to install, provided the bore isn't worn (if you can 'jiggle' the valve at all in the housing, it's worn).

The pump isn't *too* hard to replace, but the trans *does* need to be disconnected from the engine and moved back (or removed outright) -- it's right behind the torque converter.

If you go as far as replacing the pump...
- Give some thought to putting in a new torque converter; you're there anyway, and they do go bad.
- There are 10-vane (OEM) and 13-vane pumps. The 13-vanes are supposed to be HD, but the 10-vanes are just fine for most applications. I wouldn't worry about beefing up the pump assembly.
- Pumps go bad, but they can last a long time before they blow up. Usually, you'll hear a whine from them, but they can literally last years after the whining starts.
- If you're going after the pump, you're in a good place to do the full rebuild, if you're in for replacing the clutch packs, etc. This is where you *do* get the beefed up parts -- clutches, sunshell, etc., etc.
- After the new pump is installed, and you're going to reinstall the torque converter (new or existing)... remember there are THREE seating actions, and all three must occur, or you'll destroy the pump on the first start. Also, if it's not fully seated, there usually won't be enough clearance between the TC and flexplate, when you put the trans in position to reattach them together. So make sure it's fully seated.

Finally, if you're putting in a new converter, it's good practice to pour a quart of fluid into it, prior to installing it into the pump -- otherwise, it runs dry on startup, and has to wait several seconds for fluid to fill it. Same thing if you're reusing the old converter -- drain / replace the fluid from it, before reinstall.

- You can reuse the TC <> flexplate bolts, but it's good practice to get new ones.

If you remove the flexplate (like to do the rear main seal, 'since you're there')... be SURE to replace the flexplate <> crank bolts with new ones, and also use threadlocker (I think medium / blue is the right strength, but double-check).

I hope this helps a bit.
Yeah thx for the pump advice.

The tcc valve is in the pump on the opposite side of the pr valve n boost. On the march 06 models and later, they installed a turbine shaft speed sensor, which unfortunately is right below the boost valve port next to the valve body. So you have to remove the pump to get to it. Otherwise I'd be going with option 3 below.

So about a pump....(I cancelled those purchases to think about it) 1- I could either buy a new cover kit and body, put it together- that I know outside of some freak defect that it's addressing what I believe to be the problem, in total. 2- I could buy a remanned pump, which is about half the cost, or there abouts, and would probably be fine (any experienced w remanned pumps?).... 3- I could buy a sonnax tcc valve (no reaming required with that one), a transgo boost valve, and a transgo redesigned PR valve (uses untouched parts of the pump cover bore), and this may very well address the issue, BUT, it's a lot of work to remove the trans, and I really don't want to come up empty handed and see that the pump is scored, or that there's still a wiggle going on, even with new parts.

Going to mull a bit here, but I don't have time to F around. Got to make a decision. Also about rebuilding the entire trans, I doubt it, I've never even done anything like this, and I don't have time in case I F anything up, it's my main driver. I have some help with the job though, from someone experienced, but don't want to wear out my welcome.
 

Reprise

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So I looked around a bit more...
- I found what you're talking about with the Input Speed Sensor (ISS); added around 2006.
Unfortunately, it means that the pump now has to be removed in order to remove the ISS connector, which will then allow the boost valve to be accessed. It can't be done via the sump (via the VB access hole) any longer.
(Info for the uninitiated): https://www.transmissiondigest.com/november-2007-issue/

- I also found that you've been discussing this on LS1Tech. From that thread, it looks like post #15 resolved the issue for the OP. I don't think you need all the 'prerequisites' he had in place before he replaced the boost valve with the .490 Sonnax; start with that valve, directly.

Unfortunately, that now requires a lot more work, with having to remove the pump. I feel for you. There's a couple of diagrams at the first link above that show where the harness mounts to the pump. One of the mounts is directly behind the connector. If that could be reached via the VB / sump, you could move the connector, and have access to the boost valve (which is still a b!tch to get out from that spot, as I mentioned). But I see no access. From what I see of that mount point, you might be able to break off the connector from the mount, with no ill-effect, if you had access to it. That assumes that the mount wouldn't break loose and start rolling around in the pump assembly, so I don't think I'd tell you to 'go for it', based on the limited info I have.

I don't think the pump itself is the source of your problem, or you'd have pressure issues under a lot more conditions than just this one. So while you might entertain replacing other parts visited along the way to the boost valve, unless a new (or remanned) pump has all of the updated parts you've been talking about, I'd stay away from an entire pump assembly, unless...

If you can get some confirmation from the pump vendor that all of the parts you've been talking about are replaced / upgraded where needed, then you'll save a bit of time by replacing the entire pump, which could be important (I saw you mention this is your daily). More expensive, yes, but if time is critical, it could be worth it.

Fingers crossed that this works out for you.

Video on removing the pump:

If you can rig up a puller like he shows, it will make the job easier. Dedicated ones run around $75, but you could probably rig up a 3-jaw. Just take care not to scratch up / mar the stator shaft.
If you don't have a puller, a pry bar will get the pump out (via the underside, through the VB mounting plate). You'll need to 'rock' it out, prying from alternate sides.

Also, I'd use a pick tool to spin the clips around as needed & pull out the TCC solenoids, rather than a nail, like he uses.
 
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hollywood6964

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So I looked around a bit more...
- I found what you're talking about with the Input Speed Sensor (ISS); added around 2006.
Unfortunately, it means that the pump now has to be removed in order to remove the ISS connector, which will then allow the boost valve to be accessed. It can't be done via the sump (via the VB access hole) any longer.
(Info for the uninitiated): https://www.transmissiondigest.com/november-2007-issue/

- I also found that you've been discussing this on LS1Tech. From that thread, it looks like post #15 resolved the issue for the OP. I don't think you need all the 'prerequisites' he had in place before he replaced the boost valve with the .490 Sonnax; start with that valve, directly.

Unfortunately, that now requires a lot more work, with having to remove the pump. I feel for you. There's a couple of diagrams at the first link above that show where the harness mounts to the pump. One of the mounts is directly behind the connector. If that could be reached via the VB / sump, you could move the connector, and have access to the boost valve (which is still a b!tch to get out from that spot, as I mentioned). But I see no access. From what I see of that mount point, you might be able to break off the connector from the mount, with no ill-effect, if you had access to it. That assumes that the mount wouldn't break loose and start rolling around in the pump assembly, so I don't think I'd tell you to 'go for it', based on the limited info I have.

I don't think the pump itself is the source of your problem, or you'd have pressure issues under a lot more conditions than just this one. So while you might entertain replacing other parts visited along the way to the boost valve, unless a new (or remanned) pump has all of the updated parts you've been talking about, I'd stay away from an entire pump assembly, unless...

If you can get some confirmation from the pump vendor that all of the parts you've been talking about are replaced / upgraded where needed, then you'll save a bit of time by replacing the entire pump, which could be important (I saw you mention this is your daily). More expensive, yes, but if time is critical, it could be worth it.

Fingers crossed that this works out for you.

Video on removing the pump:

If you can rig up a puller like he shows, it will make the job easier. Dedicated ones run around $75, but you could probably rig up a 3-jaw. Just take care not to scratch up / mar the stator shaft.
If you don't have a puller, a pry bar will get the pump out (via the underside, through the VB mounting plate). You'll need to 'rock' it out, prying from alternate sides.

Also, I'd use a pick tool to spin the clips around as needed & pull out the TCC solenoids, rather than a nail, like he uses.
Yeah if I had to bet, I'd say the common denominator here is the spring to the pressure regulator valve. A tonne of work to just replace that, which comes w the boost, and then of course do the PR valve at the same time. I'm confident this would solve the problem, based on the others replies and me doing a line pressure test.

But man this is a lot of work, just to rebuild a pump that was rebuilt 50k ago. My guess is it would work anyway, especially the redesigned transgo pr valve. But if I come to find out it doesn't work, because the hole is bored out, then I'll have to do it again, and that'll be the real B*tch.

And I agree, a bad pump all together would be all the time. Now, since the rebuild was just done 50k ago, and PO lost first gear, might mean he was having issues w that pump already, and just was driving it anyway. Finally burned up the first gear clutch. Shop puts in a new PR n boost valve assembly, n it works fine for a while. Now 50k later, n some more wear on that hole, same boat as before. Or it could be just a failed part, that failed early, n a cheap but time heavy fix........

Sourced a new pump, both halves, has everything, cheapest I've found is about $450 all together, has a 1 yr, of course no upgraded parts, but being new that unit can last a LONG time. Cheapest remanned I've found $275 after core send back- but who knows on that, and they have used valves inside as well. Major company remanned is about 400, n that's w a core send back, so new is a better option. Replacing the PR valve w the transgo one, a transgo boost n sonnax TCC valve is about $100.

I'm leaning new pump, only because I have to take the entire damn thing apart, n it has 175k on it, n it was just rebuilt 50k ago. But doing for $100 would be nice. I'm all but out on the remanned.

W that info, what's your take?
 

Reprise

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W that info, what's your take?

Well, since you asked... :wink:

I have a feeling that 'rebuild' doesn't always include 'pump', if it's not explicitly stated. Just a feeling, and I won't detail the 'why', so as not to get too far off track.

But... now that we have a good idea (?) of the problem... and you have a shop that acknowledges doing the rebuild on that trans (although you didn't own it at the time, granted... ) -- I would give some consideration to stopping by for a chat with them, to see if they'll attempt to make good on swapping out the boost valve for you (they'll do it quicker, and they have more experience).

If they were to agree to, say, comping the labor, since it's technically a comeback (and I don't care about the 'when'... a rebuilt transmission should be issue-free / last longer (mileage-wise) than it did.)

The above is totally up to you, and I recognize there may be a 'trust' issue with them, that you wouldn't have if you did the work yourself. Believe me, I understand. :iagree:


They'll discount the accuracy of the info (re: issue / fix) if you tell them you got it online, so be careful, that way.

TL: DR - To cut specifically to your question - new / reman / self-service -- I think I agree with you. Get a brand-new pump. Maybe *still* replace the boost valve, since that seems to be a continuing (?) issue with this particular unit. It won't take that long to swap, with new pump in hand, and the Sonnax valve doesn't cost a fortune, either.

PS: Make sure to get a new pump gasket, if they don't include one (GM: 12337931).

You may be able to recoup some of your cost by rebuilding the old pump, once you get it swapped out. Just a thought.
 
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hollywood6964

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Well, since you asked... :wink:

I have a feeling that 'rebuild' doesn't always include 'pump', if it's not explicitly stated. Just a feeling, and I won't detail the 'why', so as not to get too far off track.

But... now that we have a good idea (?) of the problem... and you have a shop that acknowledges doing the rebuild on that trans (although you didn't own it at the time, granted... ) -- I would give some consideration to stopping by for a chat with them, to see if they'll attempt to make good on swapping out the boost valve for you (they'll do it quicker, and they have more experience).

If they were to agree to, say, comping the labor, since it's technically a comeback (and I don't care about the 'when'... a rebuilt transmission should be issue-free / last longer (mileage-wise) than it did.)

The above is totally up to you, and I recognize there may be a 'trust' issue with them, that you wouldn't have if you did the work yourself. Believe me, I understand. :iagree:


They'll discount the accuracy of the info (re: issue / fix) if you tell them you got it online, so be careful, that way.

TL: DR - To cut specifically to your question - new / reman / self-service -- I think I agree with you. Get a brand-new pump. Maybe *still* replace the boost valve, since that seems to be a continuing (?) issue with this particular unit. It won't take that long to swap, with new pump in hand, and the Sonnax valve doesn't cost a fortune, either.

You may be able to recoup some of your cost by rebuilding the old pump, once you get it swapped out. Just a thought.
Yeah it comes with a rebuiding of the pump. Like I said, my worry is that the pump was already the shts, but would "do" with a rebuild kit. Not that it was likely checked for spec, but just quick short hand wobbling and parts thrown in. 50k later is still more wear, especially if it was already semi-loose fitting. I could be wrong, but I don't want to be greasy and my work truck on jack stands, and me needing to rent a truck for the next week because I hoped it was just a few parts - wrong.

I talked to them- not going to comp me on that. Now I didn't explicitly ask, but you know the deal. However he does agree with me that it's the pump, or at least a pump part issue. Probably just the f'n PR spring.

Yeah I've thought about replacing the valves too on the new one.

I've also thought about the old one for selling.

One thing, the problem isn't getting any better, only worse. Progressively. Doesn't have to get as hot for it to rear it's ugly head- although same symptom. I'm hoping I'm not too late, although I'm avoiding the problem like the plague while driving, and the pan looked good just 10 days ago or whatever it was. At least going through this process, if I do eventually need to rebuild it (I'm sure I will), this will be a good primer to being able to remove and take apart the damn thing. So I won't be apprehensive at that point.
 

Reprise

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However he does agree with me that it's the pump, or at least a pump part issue. Probably just the f'n PR spring.

Then a new pump *should* fix the issue, at least. Maybe a little overkill, but the only test / diagnostic you have is reassembly / test drive, and you only want to do that job once.

If I were in the neighborhood, I'd offer to stop by and help, of course. But I'm a couple thousand miles from you, assuming you're in Cali. So my wishing you 'good luck' is about all I can do, from here. 🍀
 

hollywood6964

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Then a new pump *should* fix the issue, at least. Maybe a little overkill, but the only test / diagnostic you have is reassembly / test drive, and you only want to do that job once.

If I were in the neighborhood, I'd offer to stop by and help, of course. But I'm a couple thousand miles from you, assuming you're in Cali. So my wishing you 'good luck' is about all I can do, from here. 🍀
I'm in AZ, but I appreciate it. And yeah, I'm feeling the overkill. This is like a bmw in that respect, so much labor for likely a spring and an altered PR valve, that you end up replacing a tonne of sh*t to make use of the labor. Might even replace the rear main, I think it has a little seepage.
 

hollywood6964

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Then a new pump *should* fix the issue, at least. Maybe a little overkill, but the only test / diagnostic you have is reassembly / test drive, and you only want to do that job once.

If I were in the neighborhood, I'd offer to stop by and help, of course. But I'm a couple thousand miles from you, assuming you're in Cali. So my wishing you 'good luck' is about all I can do, from here. 🍀
well sh*t, I can't source a new pump body, however I did get the new pump cover kit in the mail. This one is a 7 1/3 stator, but the gm part number is different on one box to the box inside, and the part number on the wrapper is the same as the second box, but doesn't show up on gm computers as a reference. Some parts reps have told me they think it's fine, but they just may have used that part number for a couple months and then changed suppliers, thus the goofy packging. IDK. A 24243749 pump body is needed, but it's discontinued (I ordered one and then it got refunded, then I called a tonne of places and nodody can get one). One common denominator I've found is 24201073. This seems to be a common pump body, but not sure if it'll mate up properly with my new or old pump cover. thus far I have bought parts in case I have to rebuild the old pump body, there will be a few leftovers, and upgrades, but I'm lost on this new pump body.

My fear is this former owner overheated the vehicle (not to get into that, I'm fairly sure), and he warped aluminum certain parts, and the pump would be one. Also fairly sure there's a head gasket/head issue at higher temps (above 215f), but that's for another day. So I don't want to open the pump, and rebuild the body, and find out later there's a slight warp and it's wearing the vanes and rotor out in short order, all over again (I'm hypothesizing here). I've spent many hours trying to get an answer over the phone, etc, and not happening.

If anybody knows about the pump bodies, and if they interchange much across the board (always exceptions, I know some take an o-ring in between the pump body and pump cover, probably changes things)?

Little stumped on this. I could just buy a remanned entire pump, but even then I have some companies saying that when the pump comes out, some are 6 1/3 inches stator, and some are 7 1/3, and there's no way to tell what I have. A few say they know it's the 7 1/3 for sure, and I tend think it is, but not sure.

 

hollywood6964

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Glendale
Took apart the transmission pump and the culprit was the pressure regulator valve.

You can see the flat land was completely worn down so far it was grinding into the rounded valve itself.
Replaced the pump cover and started with regular gm valves it came with.

Also replaced the pump body with a used machine one and rebuilt it with all new gm parts- veins, rotors, guides sealing rings, springs, pin n orings. Tight fit, but seems to be working.

The inside of the housing looked decent, wasn't all metal greyed out.

Also replaced the 1-2 shift kit all together w an original gm. Yeah plastic piston, but it's all new so it should help an odd 1-2, and it has. Of course it may be because the pump was replaced, but I'm sure the housing m pin bore was worn a bit. Might replace the w the metal piston later.

So far I've warmed it up all the way and drove it for about 45 minutes, shifting from d to r to d and short stopping etc, to where it would show the problem all the time, and it has been working thus far. Don't want to count too many chickens, but it's running pretty good right now.

In the end, if I could've got to the PR valve with out removing everything n replaced it w the transgo drop in, and for good measure, the transgo .472 boost, I would've, and that probably would've worked just fine. At least for a while until that bore cleaned out further. Because it would've.

Am I too late- there was already some grey metal sludge on the magnet after only 800 miles.....to some extent probably, but it wouldn't have made it through the summer with that worsening issue for sure. Hopefully I've bought myself some significant time.
 

hollywood6964

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Feb 13, 2022
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Glendale
Here's a couple pics of the PR valve, I'm sure the bore was worn badly as well.
 

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Reprise

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Glad to hear you got this resolved. Always nice when us 'shadetrees' figure out a problem, without having to use the 'parts shotgun' or reworking the solution a bunch of times :thumbsup:
 

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