Upgraded fan clutch

Matt

Silver Supporter
Just wanted to post some information on the fan clutch that I got via @Mooseman (thanks mate!).

Those of us that have the crappy EV fan clutch that eventually craps out are better served replacing it with the thermo clutch. But if you look at the description and photos on RA it could cause some confusion, like it did me. Hayden is the preferred brand and there's 2 part numbers, but the 2851, when you look at the pics, doesn't have a harness hanging off it...does it come with one? :confused:

So I reached out to moose and here's the #truth:

The 2851, being thermal, has no harness, which is why you need a tune to turn off the fan codes when you use it.

The 3200 does have the harness because it is an EV.
So, there you have it, just get the 2851 and have the code tuned out and all will be good.
 

Mektek

Well-Known Member
The EV clutch does have some strange operating characteristics - I get people asking "what's that ticking sound?" . Apparently there's a firmware download to eliminate that but I don't want to pay the stealership $90 so I live with it. I don't know how old it is, but it works OK so I'm not going to change it. There's the additional hassle and cost of sending your pcm out to be reprogrammed. So it will cost you much more time and effort rather than just replacing the EV clutch.
 

Reprise

Lifetime VIP Supporter
Agreed about the 'don't touch till it's broke' part. The issue about replacing same for same is that the replacement E-V clutches often don't last even as long as the OEM did. There are some members on their 3rd / 4th E-V clutch as a result (I don't recall reading / hearing about a 5th).

Since GM even gave up and switched to the thermal clutch at the end of the run, and those clutches last a lot longer (not 'lifetime', but 80-120K mi, IIRC,) I decided to endure the pain / expense of flashing the PCM--and it's an opportunity to put some 'tuning' in it at the same time. Kinda like the old Bendix/Autolite ads - "pay me now, or pay me later'. Oh, and no more issues w/ people thinking you've got an alarm clock or a bomb under the hood...lol.
 

littleblazer

Gold Supporter
Some time in the last few years hayden dropped the lock temp of the thermal clutch to 170ish degrees. Because of this on a 75+ degree day if you're running A/C your fan will pretty much constantly be locked up. It is annoying more than anything but my truck runs cool and the ac spits icecubes.
 
OP
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Matt

Matt

Silver Supporter
I replaced my EV clutch with another EV clutch about 3 years ago and now I'm getting a P1484 code, hence why I'm going with the thermo.
 

mntegra01

Well-Known Member
So, Im doing the same in the next few weeks, getting a small surgery done, then back to work, A guy at work says you can get the clutch out with removing the shroud. I replaced the water pump using the same trick. You take out two bolts from fan to clutch, then put in 2 longer ones, like 3 inches maybe, then take the other 2 OE bolts out. that should let the clutch hang forward, but not hit the radiator, and the shaft at the back can clear the water pump pulley. then just pull fan out. Its really tight on ex cam side. but I don't mind trimming the shroud a bit if I can do it faster and not open the coolant system.
 

djthumper

Administrator
It is not likely that you will get the clutch out without removing the shroud. If he can do it I want to see it documented. Some of us have been with this platform for a long time and I have not seen a clutch replaced without taking the shroud out.
 

mntegra01

Well-Known Member
It is not likely that you will get the clutch out without removing the shroud. If he can do it I want to see it documented. Some of us have been with this platform for a long time and I have not seen a clutch replaced without taking the shroud out.
:2thumbsup: Challenge accepted, I'll give it a go, he said it should take less than an hour. What's worst that could happen? I break my own car.
 
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Matt

Matt

Silver Supporter
Me too and I did the write up on how.
 

littleblazer

Gold Supporter
The hayden clutch is a lot shorter than the ev one. If I bust the fan free I can squeak it out as long as i loosen the shroud... for the extra 10 seconds it'll take though just pull it.
 

Mektek

Well-Known Member
"Some time in the last few years hayden dropped the lock temp of the thermal clutch to 170ish degrees. Because of this on a 75+ degree day if you're running A/C your fan will pretty much constantly be locked up. "

That would be a good reason not to go with the hayden thermo clutch. If you are in a hot climate where the temperature is usually above 80 then the clutch will be locked most of the time and your engine will sound like a tractor trailer and will have lower fuel economy.
 

Mooseman

Moderator
I have two. One is a Hayden, the other a 4 Seasons. Except at startup, neither get locked up. They might pull more at idle if it gets hot enough but do variate speed as they should.

I haven't heard neither ever lock up while moving. Might have spun a little harder at idle but that's about it.
 

littleblazer

Gold Supporter
I have two. One is a Hayden, the other a 4 Seasons. Except at startup, neither get locked up. They might pull more at idle if it gets hot enough but do variate speed as they should.

I haven't heard neither ever lock up while moving. Might have spun a little harder at idle but that's about it.
Mine sounds like a semi after running for a few minutes. Sustained highway driving is actually a little annoying. Quick google shows it is a relatively normal occurence. Think I should try another one. Problem was I did the swap in the winter so it took 5 months for it to start happening.
 

mntegra01

Well-Known Member
Me too and I did the write up on how.
Just had a few days at the beach and got home last night and had a vasectomy done this afternoon. I will check out that write up Matt, I sell parts for these all day and don't work on them much until I had a crash course on everything. I wander into the shop some,but its always an Acadia, Enclave or Traverse in there torn apart.

So it may be a week or two till I get into the engine again. I should have my PCM back from @Kelly@PCMofNC. My work called and said I had a package. I'll go in tomorrow and find out.
 

mntegra01

Well-Known Member
So I did my fan clutch today since I can't stand waiting. I did not remove the shroud. I used two longer M8 bolts. A 60MM would probably be the best. Take 2 completely out, then insert the longer ones a few threads in, enough to not come out by wiggling a little bit. then take the other two fan to clutch bolts out. pop the fan off the clutch. Unplug the connector. Using the long bolts lets the hub hang inward towards radiator so that it can clear the water pump nub. I had to kinda rotate the fan around, counter-clockwise -> towards the battery and let the ex cam side be between two fan blades. pulled forward on the shroud a lot and some wiggling and it came out. The shroud did crack, but only about half an inch at the connector cut-out on the driver side of the shroud. And actually after it cracked it was a lot more flexible, If I did it again (on another vehicle) I would trim that to allow the upper shroud to flex out more.

Putting in the thermal clutch was much super easier since it is thinner than the electro one. The electric clutch would be a real bear to put back in, but I'm sure its possible.

If I was trying to bust ass and a real mechanic, probably be a 30 minute job.



also, I think my AC not working was due to the clutch. It would work on first start up, but after driving and stopped for lunch, then get back in the vehicle, the AC would not work. clutch would not engage. I was trying to use AC in stopped traffic on highway and temp gauge went a touch past middle, turning the ac off calmed the temps down. Hasn't been so hot in RVA this week, but the AC worked after lunch yesterday, again this morning after fueling up. So replacing the clutch may have solved my AC problem,

I do know that it had been replaced before, at 180K miles, probably been replaced a few times. The screws that hold the connector to shroud were missing.
 
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xavierny25

Well-Known Member
I didn't want to start a new thread with the same issue so I'll post this here.

I replaced the thermal fan clutch on the envoy today and noticed that it is way louder then the 1 I replaced. The reason I replace it was on start up it was loud until about 2 minutes after all was good. I also noticed my engine always running on the cooler side never going above 210 and lower side of 190's when operating on the torque pid. The replacement is a hayden and its doing some stuff im not used to I guess or there might be a break in period I'm not aware of.

1st.The Hayden is just as loud on start up.
2nd. monitoring temps and the operating temp at idle is 195-197
3rd. Once I get moving and with the ac running the temps creep up into the 220's.

Once it reaches into the 217-220's I can hear and feel it through the revs that the thermal fan clutch has fully engaged and it begins to cool things down to get back into the 190's.

Does this all sound normal?
Should I just give it a couple days or weeks to break in?

Let me include that the 1 I replaced today was replaced by me with a used unit about 100k miles ago from a low mileage wrecked 08 envoy like mine.
I also remember I replaced it because it was doing what this new hayden is doing now.
Screenshot_20200731-155003_Torque.jpg
 

MRRSM

Lifetime VIP Supporter
Somewhere in this jumble of 19 images (most will need ZOOMING to be able to read in better detail) there may be something useful for you to refer to for Fan Clutch Diagnostics. The attached Tech 2 PATHS .PDF Document will also help with the additional refining of any Fan-Clutch Diagnostic Scanner 'Step by Steps' as well.

I apologize that the Naming Conventions for these images are in no sensible, particular order and there may also be some redundancies here. However, if you download, save, and review each one... matching them up in their proper sequence may be worth doing.

Then you'll be able to give them their proper titles as the means to organize and make use of anything worth digesting out of this 'pile of stuff'. I know this is kind of an "Information Scatter-Gun" approach being used here... but its the best that I could do:

TAFANCLUTCHWIRING.jpgFANCLUTCHA.jpgFANCLUTCH8.jpgFANCLUTCH7.jpgFANCLUTCH6.jpgFANCLUTCH5.jpgFANCLUTCH4.jpgFANCLUTCH3B.jpgFANCLUTCH3.jpgFANCLUTCH2A.jpgFANCLUTCH2.jpgFANCLUTCH1.jpg2011-06-11_194914_1b.gif2009-09-08_035103_cooling.png2007-11-10_221515_14812.gif2007-11-10_221441_14811.gif2007-11-04_020620_tsb.JPG2007-07-05_081001_TSB_on_oveheating_for_Trailblazer.jpg6ccdc946-7358-4993-a6fc-2c5c9a7ea8a4_trailblaser.PNG
 

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Mooseman

Moderator
His clutch is THERMAL, not electro-viscous.

My thermal in the 9-7x is loud on startup as well but after a few minutes quiets down. I find it doesn't pull enough at speed while towing the RV. On the last trip, it climbed to 227f and it didn't feel like it was pulling enough. IIRC, it's a 4-seizin'. I still have the one from the old TB I might try swapping into the Saab to see if it makes a difference. I do remember that it wasn't noisy on startup. Don't remember the brand on that one.

Edit: Re-reading my post above, apparently it's a Hayden.
 

Mike534x

Well-Known Member
Is that a normal characteristic with the thermal clutch? Or is that to be expected since its not running off whatever the PCM is sending it compared to the electro-vicious? Just trying to keep note for when the time comes to swap mine out.
 

xavierny25

Well-Known Member
Just a quick question about the picture posted,, what Torque PID is showing that 75.7 psi oil pressure!?
I think that just a standard 1 I pulled from the pull down list. I can look into it a little deeper to get you more info if needed on my lunch break.

Edit: keep in mind I have the 4.2 in this envoy and I never really pay much attention to that gauge unless it went to zero at some point then I probably would.
 

TJBaker57

Well-Known Member
I think that just a standard 1 I pulled from the pull down list. I can look into it a little deeper to get you more info if needed on my lunch break.

Edit: keep in mind I have the 4.2 in this envoy and I never really pay much attention to that gauge unless it went to zero at some point then I probably would.
That's the thing,,, I didn't think there was an oil pressure pid that returned a value, even an imaginary one, on the 4.2. I thought I always got "no data" on those.
 

TJBaker57

Well-Known Member
On a related note....

It would seem to me that whether the control mechanism on a cooling fan was controlled thermally or electrically wouldn't the same fluid still need to pump out of the clutch and back into the reservoir at first startup just the same? And thus , both types would exhibit the possible roar at startup?
 

Mooseman

Moderator
I haven't found any rhyme or reason as to which ones roar or not at startup. It may be the position it stops at that allows the silicone lube to drain into the reservoir. That could be caused by the fan's weight balance and where it comes to rest.
 

xavierny25

Well-Known Member
That's the thing,,, I didn't think there was an oil pressure pid that returned a value, even an imaginary one, on the 4.2. I thought I always got "no data" on those.
Screenshot_20200802-165345_Torque.jpg

On topic: I took some lengthy screen recording of what the drive home was like. I'll get that recording posted shortly.

I'm fine with the tractor sound at start up and the beginning of the drive but I'm getting it frequently while on the road. On my drive home from work today it most of gone into tractor mode 5 or 6 times.
 

aaserv

Well-Known Member
I know I read somewhere that the Electric FC is supposed to run on high for the 1st 1 to 2 mins on initial startup. I cant find it now but Im absolutely positive i read this on some kind of official GM document. Just saying i wouldnt look at that as a problem. I cant imagine how they could get a thermal clutch to do that though so i guess it just adds to the mystery of how GM designed these things.......
 

TJBaker57

Well-Known Member
I know I read somewhere that the Electric FC is supposed to run on high for the 1st 1 to 2 mins on initial startup. I cant find it now but Im absolutely positive i read this on some kind of official GM document. Just saying i wouldnt look at that as a problem. I cant imagine how they could get a thermal clutch to do that though so i guess it just adds to the mystery of how GM designed these things.......
Somewhere I have a document, TSB or some such, that more or less explains that it is not so much commanded to run at high the first couple minutes,, it's more like the clutch needs a couple of minutes to pump the fluid out of the clutch and back into the reservoir especially if the vehicle was shut down hot while the clutch was actively commanded to be 'ON' and the fluid was in the clutch mechanism. Also spoke of the item Mooseman spoke of in that the position of the clutch at rest makes a difference, not that there's anything you can do about that.

Another contributing factor is parking steeply angled nose up vs nose down. Affects the was the fluid collects inside the fan clutch apparently.
 

Mooseman

Moderator
Also spoke of the item Mooseman spoke of in that the position of the clutch at rest makes a difference, not that there's anything you can do about that.
That is just a theory of mine, nothing more.

After searching, I did find this thread with a post by The Roadie that has links to other sources of documentation "en masse":
 

Mooseman

Moderator
And it also talks about being parked in a 16%+ nose up incline causing it too. Being parked nose down has the opposite effect.

Why oh why didn't they just give us a decent radiator and efans instead of this botched experiment?
 

TJBaker57

Well-Known Member
And it also talks about being parked in a 16%+ nose up incline causing it too. Being parked nose down has the opposite effect.

Why oh why didn't they just give us a decent radiator and efans instead of this botched experiment?
Often times I see something that is a good idea, but poorly executed. Seriously,,, if a thermal element can operate a fan clutch valve why could they not make an electrically operated valve do the same.
 

TobyU

Active Member
Fan clutch?? What's that? Lol When we bought our 04 it had a fan clutch code but ran fine.
Then when it got cold out months later it started popping reduced engine power light and limping.
At first would only do it if you gave it a a little more gas than normal. Would be fine for weeks..then mess up.

Started getting the TB codes and the pedal position codes along with loss of 5v ref B I think....and the constant fan clutch and also a cam sensor code.

I swapped the cam sensor with a junkyard one and still code.
Put at ebay TB on it and was good for weeks then messed up again.
Swapped the pedal with a used one. NO change.

Mind of it's own.

Then the gear shifter stuck a couple of times in park.... Found one to two fuses not squeezing the fuse enough to make contact all the time.
The aftermarket stereo was installed with the cheap fuse taps and widened the terminals.

Got to where I could WD-40 the whole fuse block and it would be fine for days then mess up when it wanted to. Several time it consistently was great for days after lots of WD-40 onto fuses but then that stopped working.
I pulled the fuse block apart and used contact cleaner and some copper contact enhancement past on the tabs to try to keep good connections.

Was good for 2 days then back to messed up.

I was to the point or keeping scantool plugged in all the time and when it would go into reduced power mode I would clear codes and it would come back to life for a mile or two.
Did this for days putting around town.

So a light from the sky opened up and a small winged angel with a pop up message bubble appeared to me and I thought "what a bout unplugging the fan?"
I did this and it ran perfectly!
Been a few months now and not a single reduced engine power light after start up.

Screw that fan!!!

It doesn't run hot. I can't really tell if it runs too fast but it is not very tight when I spin it.
Compared to the old 4.3 in last Blazers....the fan sounds slower than normal or at least normal as those always sounded like they were a truck going uphill.

Damn over-engineering mess ups!!! K.I.S.S
This is why I keep older cars but they still mess things up.
 

Mooseman

Moderator
With an unplugged fan, unless it's locked up, you run the risk of an overheat since it would just freewheel. A/C performance would also be poor.
 

TobyU

Active Member
With an unplugged fan, unless it's locked up, you run the risk of an overheat since it would just freewheel. A/C performance would also be poor.
Might be the way it's supposed to work but not the case on mine.
It never runs hot and ac is fine- except for piss-poor design of actuator motors resetting and messing up on battery removal.
Dumbest idea ever contender!
I have to manual flip one near glove box from hot/cold every season for pass side and driver's works but is a few clicks toward warm so never gets as cold as pass side.
 

Mektek

Well-Known Member
You have to deal with the signs of an aging GMT. That's why we have this group - between us all we've had all the various issues come up and good results with fixing them.
The actuators have a poor design and manufacturing, but can be repaired or replaced. I repaired 3 broken actuators a few years ago and today they still work properly and I don't fear disconnecting the battery - I make sure that the recalibration properly completes before starting and everything is OK.

Someday someone will come up with a good efan upgrade :yes:
In the meantime the stock fan clutch does work well enough. It wont last forever and has some quirks - but it lasts long time. Replace your problematic unit with a Acdelco (Behr) or Hayden and you should be OK for many years. It sounds like there is a problem with the speed sensor that's overloading the 5v power.....
 

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