4L60e / transmission gurus - need analysis / opinions

Reprise

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Hoping I can get some confirmation / clarification on what might be happening here...

Background...
2003 Envoy, w/ 5.3L, about 145K on the clock...

Professionally rebuilt by local mech about 1yr (< 1000mi) ago - HD clutches / band, Beast, 3200 stall, PWM disabled, Vette servo, etc. Set up for towing. Derale stacked plate cooler. Temps consistently 150-170 F, per Torque.

Fluid looks fresh out of the bottle (light pink); level good.

Not one issue until recently.

A couple of weeks ago, when I was in the middle of a drive (fully warm / hot), I started hearing a whine...best I can describe it is as if I were driving a larger truck (like a TopKick or a semi). The noise would persist in all 4 gears and into OD (although lower in volume / pitch, as shifts progressed, was constant).

Did some research and originally suspected idler pulley. Figured out a couple of days ago that it's definitely the trans.

1-2 is very firm (not harsh, not 'slamming'), and a shade late. Other shifts are firmer, but less noticable. The truck also feels like it's 'struggling' a bit under acceleration from a stop - as if it had some type of internal resistance.

I figure that the line pressure has been maxed out. Shift points in 2-3-4, OD seem to be the same.

The other thing I noticed is that there is NO data via Torque - all other data points are fine / look normal - but no data on the trans temp. I know it's not running 'hot', and I know the pump is still working (not seized) - otherwise, it would have locked up by now, is my thinking.

So I figure that the PCM has lost communication w/ the trans, and consequently boosted the line pressure to compensate.
Being an '03, there's no separate TCM.
There are also no codes pending / stored, no CEL.

Now here's something very strange - a couple of periods during the 3 trips I've made with the truck (2 of them the other day, when I drove it to / from work, due to flooding (rain)) - I noticed that the whining stopped, and the trans behaved absolutely perfectly again. However, there was STILL no temp data in Torque when these instances occurred.

I can drive the truck at highway speed (55-70mph); the one time I did, was one of those 'good' periods that I described above - 20mi, no issues for the rest of the drive until I parked the truck at work.

The truck is supposed to go in in Sept. for 1yr checkup (to extend warranty another year).
If this is still ongoing then, I'll take the shop for a drive and demo it for them.

However, I'm going to be under the truck doing some other stuff, and if I can fix it before Sept, I'd like to do so. By 'fix', I do not mean dropping the pan or removing the trans - if that needs to be done, it's going back to the mechanic.

During my search on this, I've seen some possible reference to a bad TCS - not sure if that's relevant or not. Right now, I can't find info applicable to my issue online - and I don't have my ATSG manual handy at the moment.

If any of our knowledgeable transmission / 4L60 people might have an idea, I'd appreciate any info. Thanks in advance.
 

Mooseman

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Dec 4, 2011
25,260
Ottawa, ON
Is the whining like in my video I posted in this thread?
My EXT is DEAD

If it is, I'd be worried about a major failure. Shifts were brutal and had no reverse. But then you said your whine is constant. Mine was irregular but engine speed dependent. Parking pawl was also effed.
 

Reprise

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Is the whining like in my video I posted in this thread?
My EXT is DEAD

If it is, I'd be worried about a major failure. Shifts were brutal and had no reverse. But then you said your whine is constant. Mine was irregular but engine speed dependent. Parking pawl was also effed.

Thanks for posting that, Moose. I had actually watched your vid last year when you first posted it, and viewed it again today. Yours is higher pitched - I'd compare yours to a turbine-type sound, if you will. Also, it sounds like yours largely goes away after the 1-2, and mine is present throughout the gear range (it changes in pitch at each shift, from high to low, and climbs with RPM).

Also, I still have reverse - no issues there, and I don't have any noise outside of the whine (like the clicking on your video).

@Tiggerr - appreciate your mention of the TC...if I try and locate the noise in-cabin, it does sound like it's in the trans tunnel / hump area. Also, if I roll the window down, it sounds pretty much the same, just a little louder (naturally).

I have to go out later today - I'll try and record some video (or at least audio) of the sound / experience, and post it here when I get back.
 

Reprise

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@gmcman - Not yet, but I plan to. Ironically, when I drove the Voy yesterday to capture the issue on my phone - the issue went away again 15min into the drive (so I actually have one vid w/ the issue, and one *afterward* without).

As for why I haven't posted them - difficult to hear, and the MP4 vids are > 400mb and > 58mb in size - I don't feel like crippling the GMTNation servers with 1/2 GB of low-quality audio. Instead, I'll find another way that improves audio while making for a much smaller filesize. This truck isn't my DD.

Other things I did:
- checked all applicable fuses - all were fine.
- checked Torque during 'issue present' and 'issue not present' - still no data returned on trans temps.
- there is now a pending code, but it's for...the fan clutch. Last seen > 2yrs ago, also in the summertime.

After some more analysis, I'm starting to lean toward the EPC solenoid (force motor) sticking 'open' (although that doesn't answer the 'no data' question.)

Since that's a pan drop to check / replace the EPC, as I said earlier - the mech will be working on this. To GMCMan's point - I paid for a warranty, and I intend to take advantage of it. Now if I can just make sure the issue duplicates itself when I take it in. :Banghead:

Addn'l comments / ideas welcomed, of course. :thankyou:
 
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Mooseman

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Dec 4, 2011
25,260
Ottawa, ON
You won't cripple our servers since you can't upload vids directly. You'd have to upload to YouTube or other hosting site and post the link.
 

snoozer

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May 15, 2017
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Home
I debated on if I should post or not since I am new here, but I am going to anyway.
Are you sure it is not your fan clutch?
Why I ask is when you described the sound as like a semi, loss of power, shifting issues in lower gears, just about everything you wrote all sounds like the problems I was having with a new fan clutch that was installed to my 2003.

Heck when my first fan clutch locked up fully engaged the first thing I noticed other then the noise was how the tranny was shifting, it had a loss power so bad you had to floor it to get it to move, but since I have come across normal/ non electrical fan clutches in the past that would scream & holler like this when bad it didn't take me to long to figure out what was wrong.
I am in the process of putting a 2008 fan clutch on mine & getting a pcm tune.
Thanks to mooseman helping me out.

If you have already thought of this & eliminated it as your problem please ignore my reply.
 

Sparky

Member
Dec 4, 2011
12,927
Torque not seeing trans temps doesn't surprise me that much. I've run into that before. I'd file it away as a data point, but don't base too much off of it yet.

When the whine is occurring, park the vehicle and rev the engine in park some. Does it still whine? If so, it isn't any major guts of the transmission (except maybe something in the torque converter, though I don't recall any cases of the torque converter causing the whine).

If an accessory is screwing up they can pull a lot of power off the engine. When the fan clutch jams up and sticks at full blast it is amazing how much less power the engine has left to rev up. Sure, upwards in the power curve it isn't as noticeable as the engine is making plenty more power, but at lower RPM the HP output is a lot less so the drag from a full blast fan is a lot higher percentage usage of the current available HP.
 

Reprise

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I debated on if I should post or not since I am new here, but I am going to anyway.
Are you sure it is not your fan clutch?
Why I ask is when you described the sound as like a semi, loss of power, shifting issues in lower gears, just about everything you wrote all sounds like the problems I was having with a new fan clutch that was installed to my 2003.

Heck when my first fan clutch locked up fully engaged the first thing I noticed other then the noise was how the tranny was shifting, it had a loss power so bad you had to floor it to get it to move, but since I have come across normal/ non electrical fan clutches in the past that would scream & holler like this when bad it didn't take me to long to figure out what was wrong.
I am in the process of putting a 2008 fan clutch on mine & getting a pcm tune.
Thanks to mooseman helping me out.

If you have already thought of this & eliminated it as your problem please ignore my reply.

You, sir, are the winner! LOL Good job, and thank you!

Thanks to Sparky, as well, who advised seeing if the noise was duplicated out of gear - it was. Once I had that answer, I started looking at the fan clutch.

Ordered the Hayden thermal, along w/ a replacement WP (since I'm 'there') from RA yesterday - will have it tomorrow. Then a bunch of work begins (see my other post from today with all of that listed).
 
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Locksmith

Member
Nov 19, 2017
76
Columbia,SC
I debated on if I should post or not since I am new here, but I am going to anyway.
Are you sure it is not your fan clutch?
Why I ask is when you described the sound as like a semi, loss of power, shifting issues in lower gears, just about everything you wrote all sounds like the problems I was having with a new fan clutch that was installed to my 2003.

Heck when my first fan clutch locked up fully engaged the first thing I noticed other then the noise was how the tranny was shifting, it had a loss power so bad you had to floor it to get it to move, but since I have come across normal/ non electrical fan clutches in the past that would scream & holler like this when bad it didn't take me to long to figure out what was wrong.
I am in the process of putting a 2008 fan clutch on mine & getting a pcm tune.
Thanks to mooseman helping me out.

If you have already thought of this & eliminated it as your problem please ignore my reply.
What brand did you replace you fan clutch with? Part number and cost? Are you happy with it?
 

mrrsm

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Oct 22, 2015
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Reprise

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Jul 22, 2015
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What brand did you replace you fan clutch with? Part number and cost? Are you happy with it?

I got a Hayden 2851. You'll find it recommended on this site. Note that if you do a parts lookup by vehicle, it's likely not going to list as a match - because the OEM is a thermo-viscous, with the harness lead that reports to / from the PCM. I believe the 2851 is normally used on the GM pickups.

A couple of things to keep in mind...
- To use this, you *must* have the PCM tuned to have fan codes removed; otherwise, the PCM is going to throw OBD codes, turn on SES light, etc. This is because it's going to send commands and expect a response to / from the fan clutch, but there won't be any. I used Lime-Swap (again, you can find info on this site, or go to their website. PCMofNC also does tunes for this as well (and whichever way you go, you may as well have them put in whatever additional tune parameters you want - I had the throttle body delay and torque mgmt removed / lessened along with a couple of other things, for example.)

Remember that I have the 5.3L, so make sure the 2851 will retrofit to the 4.2L. I think it will, but make sure you check. Again, you won't have to go any farther than this site to find out - just search on Hayden 2851 and review the results. Most here have the 4.2L; after you read through a couple of responses, you'll know which model # you need. Most everyone here recommends Hayden as the best / most reliable on this part.

I got mine from Rock Auto; cost is listed there at $99.79. Because of what's involved in replacing it, I also did my water pump & replaced my serpentine and A/C belts. New coolant, hoses, t-stat and hose clamps were added as well, along with an alternator I'd had waiting for this project. That way, I figured, I won't have to worry about the front end of the engine for awhile. Of course, now I'm thinking about swapping out the cam when winter's over...lol...figures, right?

Warranty on the Hayden is 12K/1yr - but it should hopefully be several years before you need to replace it. Depending on the age / mileage of your truck, it may be the last one you put on.

So - I pulled the PCM, which is below the battery tray for the 5.3L; 4.2L guys have it much easier (not that mine was that hard), and sent that off to Jeremy @ Lime-Swap so that it could be flashed while I was doing the work. Came back right when he said it would; it was back before I was finished with my work (my Voy isn't a DD, so I can work on it in a fairly relaxed fashion. Some might say 'very relaxed') :rolleyes:

Once I got everything back together, it was time for the verdict.
Vehicle started right up, no codes, all was well. Note that with the thermal clutch, it does run at cold startup for a couple of minutes. That's normal.

Took it out for a drive - coolant temp was a rock-solid 195F, per Torque; dash gauge registered at the same place it had before the swap.
With that completed, I packed my suitcase and headed off for a 600-mile round trip to the southern tip of IL & a very brief stop in KY.
Not. One. Problem. Either on that trip, or since returning.

Verdict: Highly recommended. This site makes it easy, as others have done the research & engineering for you :smile:
I absolutely hate the tick-tick-tick of the EV clutch, and its continual need for replacement. When you figure that GM went to the traditional thermal for the last 1-2yrs of the GMT360 run, it only makes sense to put one of these in. Yes, you're in for the cost of the clutch plus a tune - but it's $ well, well spent, IMO. You get benefits on top of the improved fan clutch - look at it that way.

I did take some pics of my work, but haven't finished the writeup yet. Although I'm sure there are those who will say... "then, what's this?" :dielaugh:
 
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Locksmith

Member
Nov 19, 2017
76
Columbia,SC
I got a Hayden 2851. You'll find it recommended on this site. Note that if you do a parts lookup by vehicle, it's likely not going to list as a match - because the OEM is a thermo-viscous, with the harness lead that reports to / from the PCM. I believe the 2851 is normally used on the GM pickups.

A couple of things to keep in mind...
- To use this, you *must* have the PCM tuned to have fan codes removed; otherwise, the PCM is going to throw OBD codes, turn on SES light, etc. This is because it's going to send commands and expect a response to / from the fan clutch, but there won't be any. I used Lime-Swap (again, you can find info on this site, or go to their website. PCMofNC also does tunes for this as well (and whichever way you go, you may as well have them put in whatever additional tune parameters you want - I had the throttle body delay and torque mgmt removed / lessened along with a couple of other things, for example.)

Remember that I have the 5.3L, so make sure the 2851 will retrofit to the 4.2L. I think it will, but make sure you check. Again, you won't have to go any farther than this site to find out - just search on Hayden 2851 and review the results. Most here have the 4.2L; after you read through a couple of responses, you'll know which model # you need. Most everyone here recommends Hayden as the best / most reliable on this part.

I got mine from Rock Auto; cost is listed there at $99.79. Because of what's involved in replacing it, I also did my water pump & replaced my serpentine and A/C belts. New coolant, hoses, t-stat and hose clamps were added as well, along with an alternator I'd had waiting for this project. That way, I figured, I won't have to worry about the front end of the engine for awhile. Of course, now I'm thinking about swapping out the cam when winter's over...lol...figures, right?

Warranty on the Hayden is 12K/1yr - but it should hopefully be several years before you need to replace it. Depending on the age / mileage of your truck, it may be the last one you put on.

So - I pulled the PCM, which is below the battery tray for the 5.3L; 4.2L guys have it much easier (not that mine was that hard), and sent that off to Jeremy @ Lime-Swap so that it could be flashed while I was doing the work. Came back right when he said it would; it was back before I was finished with my work (my Voy isn't a DD, so I can work on it in a fairly relaxed fashion. Some might say 'very relaxed') :rolleyes:

Once I got everything back together, it was time for the verdict.
Vehicle started right up, no codes, all was well. Note that with the thermal clutch, it does run at cold startup for a couple of minutes. That's normal.

Took it out for a drive - coolant temp was a rock-solid 195F, per Torque; dash gauge registered at the same place it had before the swap.
With that completed, I packed my suitcase and headed off for a 600-mile round trip to the southern tip of IL & a very brief stop in KY.
Not. One. Problem. Either on that trip, or since returning.

Verdict: Highly recommended. This site makes it easy, as others have done the research & engineering for you :smile:
I absolutely hate the tick-tick-tick of the EV clutch, and its continual need for replacement. When you figure that GM went to the traditional thermal for the last 1-2yrs of the GMT360 run, it only makes sense to put one of these in. Yes, you're in for the cost of the clutch plus a tune - but it's $ well, well spent, IMO. You get benefits on top of the improved fan clutch - look at it that way.

I did take some pics of my work, but haven't finished the writeup yet. Although I'm sure there are those who will say... "then, what's this?" :dielaugh:
Thank you for such a detailed answer, Reprise. I had a $56 fan clutch in for about a month now, and I had noticed the fan noise again and my gas mileage has dropped to 14mpg! Hoping to get the thermal clutch and send the pcm to North Carolina for the tune and hopefully he can do one thing so my transmission shifts a little more solidly!

I went with the 2008 Trailblazer ACDelco from Amazon.
I have put about 2,000 miles on it so far and no problems what so ever.
Really happy with the tune I got at lime-swap.com too.
Here's the link to the fan clutch I used
https://www.amazon.com/ACDelco-15-40144-Original-Equipment-Cooling/dp/B0016HZY2K/ref=sr_1_11?s=automotive&ie=UTF8&qid=1513634022&vehicle=2008-47-489-------------0&sr=1-11&ymm=2008:chevrolet:trailblazer&keywords=fan+clutch+2008+chevy+trailblazer
Thanks Snoozer!

[Mod edit: Posts merged. Please use the edit button or use the multi-quote function to reply to multiple posts.]
 
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