GM Radiator Fan - What I discovered of interest to all

WWDiesel · **Posted:** Wed Aug 31, 2016 9:51 pm

HER_CRD wrote:

Looking at replacing the fan clutch this weekend. Since I still have the steel fan is there any sense in changing to the plastic one?

Only if you want a little more cooling air flow through AC condenser, Charge Air Cooler, and radiator, especially during low speed driving like when in stop and go town traffic.... :wink:

And some on this forum may disagree with the above statement which is fine; but that is my opinion based on the benefits I observed after going to the 11 blade GM fan and HD NAPA fan clutch in hot 100+ degree driving in high humidity central Georgia!!! :ALONE:

Anything to help add any additional cooling air flow to these small grill vehicles that has everything packed so tightly in the front is a benefit! :roll:

casm · **Joined:** Sun Jan 29, 2006 5:05 pm **Posts:** 694

whiteninja1 wrote:

Did the GM hd fan clutch use the same bolts to hold the fan on as the Oem jeep?

Necrobump because I didn't see a response to this question, am in the middle of doing this swap, and have an answer. Well, two answers

Short answer: it doesn't appear as though the fan bolts will interchange between the Hayden 2905 (straight replacement for the OEM CRD fan clutch) and the 2986 (GM 11-blade fan clutch upgrade). I learned this the hard way today.

Longer answer: you'll want to go to your local Chevy / GM / Oldsmobuick dealer and order quantity 4 of part no. 11516869. These are the fan bolts used on the GM vehicles that the Hayden 2986 is a direct replacement for. Ran me about $6 plus tax for the set, so there's probably no real advantage to trying to get them online. They're also likely to be a special-order item unless you get lucky.

Some additional comments: I replaced what I believe was a failed OEM fan clutch with the Hayden 2905 roughly six months ago. The Hayden 2905 showed itself as dead after the Winter ended and I started using the A/C again, which was less than happy-making. Decided to tackle the fan and fan clutch upgrade this afternoon, and pretty quickly figured out that the fan bolts on the 2905 were a lot smaller in shaft diameter than what the 2986 wanted. One fruitless trip to Home Depot later, I just went to the Chevy dealer and ordered them; they'll be here in the morning.

GordnadoCRD · **Posted:** Thu Apr 26, 2018 5:38 pm

GM fan is much lighter and pulls noticeably more air.

casm · **Joined:** Sun Jan 29, 2006 5:05 pm **Posts:** 694

Late update: swap's done, and I'm confirming that GM part no. 11516869 is the correct one for the 11-blade fan bolts. They actually came with a small amount of Loctite already on them, which was a plus. No fitment issues whatsoever.

WWDiesel · **Posted:** Sat Apr 28, 2018 12:57 pm

casm wrote:

Late update: swap's done, and I'm confirming that GM part no. 11516869 is the correct one for the 11-blade fan bolts. They actually came with a small amount of Loctite already on them, which was a plus. No fitment issues whatsoever.

Thanks for pointing this out casm; I went back and added that information to the original post...
Now if we knew the bolt size, thread pitch, and length, that could be added as well so bolts could be sourced from other vendors?

Quote:

GM 11 blade fan requires four(4) GM 11516869 bolts, they have different threads and are a bit larger. (bolts to attach fan to clutch)

casm · **Joined:** Sun Jan 29, 2006 5:05 pm **Posts:** 694

WWDiesel wrote:

Thanks for pointing this out casm; I went back and added that information to the original post...

Cool, glad it helped

Quote:

Now if we knew the bolt size, thread pitch, and length, that could be added as well so bolts could be sourced from other vendors?
GM 11 blade fan requires four(4) GM 11516869 bolts, they have different threads and are a bit larger. (bolts to attach fan to clutch)

I tried sourcing them locally, but they're just weird enough that they're pretty much a dealer-only item if you're trying to pick them up in person. From what I recall, the length was the issue.

If I remember correctly (and I may not, so 'trust but verify' applies here), the GM parts guide listed the dimensions for the bolts. However, since I was standing in the local Chevy dealer's parts department at the time I heard this info, I didn't think to take down the dimensions and just ordered them. Someone with access to the GM parts fiche could probably look it up, though.

WWDiesel · **Posted:** Sat Apr 28, 2018 3:37 pm

Bingo! Found it: it is a 10mm bolt, M10 x 1.5mm threads and is 18mm in thread length, 17mm wrench head, 8.8 hardness. :wink:

A 3/8 lock washer can be used on a 10mm bolt if you don't have any metric lock washers....
That is why I never paid much attention to it at time of install as I have a huge metric bolt assortment selection cabinet, so I just grabbed what was needed.... :roll:

GordnadoCRD · **Posted:** Sat Apr 28, 2018 3:40 pm

Got mine from Diamond Supply Co. Walked in with the clutch and found some that matched. Don't remember what they were though. They were stainless, button-headed, and Torx drive.

thatoneguy · **Posted:** Thu May 24, 2018 10:07 pm

WWDIESEL Do you remember if there was any difference in mileage on the change. I have been running fine in the northern climate without the fan but with a 1 1/2 year old and a pregnant wife a/c is a must. With the a/c on and living in a very hill region on slower hill climbs or stop and go traffic 85-90* is about where the limit is on the cooling system without the engine fan. No a/c or staying above 40 mph not a problem. Its not getting hot by any means but it is climbing just right of vertical on the guage and will come back down after moving. Today I had it climb after coming up a hill so I threw the fan back on. Rather noticeable difference since my clutch seems to stay locked up all the time. Either way drove the same route I did in the morning mid afternoon with 10-15* warmer and it stayed right were it always warms up to and never any further. My biggest thing is since my fan clutch seems to be locked up majority of the time even when cold and 4 tanks one way and now 5 without a fan I can get 1.5-2mpg better without it but I am not chancing overheating it for that gain on hot days. Just trying to reason if the 3 months I would run a fan are worth $110 upgrade or not.

GordnadoCRD · **Posted:** Fri May 25, 2018 1:20 am

thatoneguy wrote:

WWDIESEL Do you remember if there was any difference in mileage on the change. I have been running fine in the northern climate without the fan but with a 1 1/2 year old and a pregnant wife a/c is a must. With the a/c on and living in a very hill region on slower hill climbs or stop and go traffic 85-90* is about where the limit is on the cooling system without the engine fan. No a/c or staying above 40 mph not a problem. Its not getting hot by any means but it is climbing just right of vertical on the guage and will come back down after moving. Today I had it climb after coming up a hill so I threw the fan back on. Rather noticeable difference since my clutch seems to stay locked up all the time. Either way drove the same route I did in the morning mid afternoon with 10-15* warmer and it stayed right were it always warms up to and never any further. My biggest thing is since my fan clutch seems to be locked up majority of the time even when cold and 4 tanks one way and now 5 without a fan I can get 1.5-2mpg better without it but I am not chancing overheating it for that gain on hot days. Just trying to reason if the 3 months I would run a fan are worth $110 upgrade or not.

OR you could get one from Ebay that's been "broke in". At worst, you still need to get a clutch. At best, you get a bolt-on complete unit that still works for a couple twenties or less.
https://www.ebay.com/itm/99-04-Yukon-Escalade-Silverado-Engine-Cooling-Fan-Blade-Clutch-GM-OEM-15017911-/273210594316?_trksid=p2385738.m4383.l4275.c10

WWDiesel · **Posted:** Fri May 25, 2018 6:08 am

GordnadoCRD wrote:

thatoneguy wrote:

WWDIESEL Do you remember if there was any difference in mileage on the change. I have been running fine in the northern climate without the fan but with a 1 1/2 year old and a pregnant wife a/c is a must. With the a/c on and living in a very hill region on slower hill climbs or stop and go traffic 85-90* is about where the limit is on the cooling system without the engine fan. No a/c or staying above 40 mph not a problem. Its not getting hot by any means but it is climbing just right of vertical on the guage and will come back down after moving. Today I had it climb after coming up a hill so I threw the fan back on. Rather noticeable difference since my clutch seems to stay locked up all the time. Either way drove the same route I did in the morning mid afternoon with 10-15* warmer and it stayed right were it always warms up to and never any further. My biggest thing is since my fan clutch seems to be locked up majority of the time even when cold and 4 tanks one way and now 5 without a fan I can get 1.5-2mpg better without it but I am not chancing overheating it for that gain on hot days. Just trying to reason if the 3 months I would run a fan are worth $110 upgrade or not.

OR you could get one from Ebay that's been "broke in". At worst, you still need to get a clutch. At best, you get a bolt-on complete unit that still works for a couple twenties or less.
https://www.ebay.com/itm/99-04-Yukon-Escalade-Silverado-Engine-Cooling-Fan-Blade-Clutch-GM-OEM-15017911-/273210594316?_trksid=p2385738.m4383.l4275.c10

Gordon, not the right GM part, the one listed on eBay is only 9 blades, not the 11 blade GM part no. (fan--15976889) Not sure if it would fit or function on our Jeeps?

thatoneguy, to answer your question, I have never ran without a mechanical fan. I live in the hot south so it never was an option. I installed the GM 11 blade fan seaking better cooling than the OEM metal fan and especially more air movement at low and idle speeds for intown driving to help AC perform better. Also GM combo, fan and clutch was available from NAPA and much cheaper with my garage pricing discount than the similar Mopar parts. And yes, the 11 blade fan made a substantial difference in the AC performance in low speed stop and go city driving.
As to fuel milage, to me it never was a concern, only better cooling.... :juggle:

GordnadoCRD · **Posted:** Fri May 25, 2018 11:21 am

WWDiesel wrote:

Gordon, not the right GM part, the one listed on eBay is only 9 blades, not the 11 blade GM part no. (fan--15976889) Not sure if it would fit or function on our Jeeps?

Yeah I noticed that, but it's the number on the part I bought from Ebay. Like you, mine is 11 blades and matches the pic of the part you list. I will correct my sig to match.
In which case,
https://www.ebay.com/itm/96-05-astro-safari-engine-motor-radiator-cooling-fan-18-thermal-viscous-clutch/232756287684?hash=item36315b18c4:g:SnYAAOSwzJ5XV3iN
should serve the same, but costs an extra 20.

thatoneguy · **Posted:** Fri Jun 01, 2018 10:17 pm

Thanks, not sure what the heck is going on but now it is unlocking after a short drive after firing up for the last 3 days. And after a long hill pull will kick on for a bit and seem to unlock again when back level cruising. I can really feel/hear when its locked and unlocked and now seems to be functioning pretty much spot on. I will keep this in mind if it does act up again.

k9adv · **Posted:** Mon Aug 06, 2018 9:08 am

Possible option for the bolts?

Dorman Help! 14040 Torque Converter Bolts "These are M10-1.50 thread and 15mm long"
https://www.amazon.com/dp/B000COCQ9C/?c ... _lig_dp_it

Also, possible options for the fan?

Dorman 621-515 Radiator Fan Blade
https://www.amazon.com/Dorman-621-515-R ... merReviews

ACDelco 15-80739 GM Original Equipment Engine Cooling Fan Blade
https://www.amazon.com/ACDelco-15-80739 ... merReviews

"I also found that the white 11blade fan dorman 620-602 AND the dorman black 11blade 621-515 are compatible with the same clutch hayden 2787/torqueflo 922787 and spins right on and clears the efan both work perfectly but the black blade is lighter and because of the curve of the blades scoops more air, but is louder when locked." (this is in a Grand Cherokee thread, but may be pertinent to our interests)
Found here:
https://www.jeepforum.com/forum/f310/gm ... ndex2.html

k9adv · **Posted:** Mon Aug 06, 2018 9:45 am

Using a 2004 Sierra 2500 with 6.0 and towing packing w/ac I see the Hayden 2786 listed as a severe duty fan clutch option, not seeing the 2986 listed (and the 2986 seems to be out of stock in lots of places), not sure exactly what the difference between the 2786 and 2986 is.

https://www.rockauto.com/en/catalog/gmc ... lutch,6812

casm · **Joined:** Sun Jan 29, 2006 5:05 pm **Posts:** 694

k9adv wrote:

Using a 2004 Sierra 2500 with 6.0 and towing packing w/ac I see the Hayden 2786 listed as a severe duty fan clutch option, not seeing the 2986 listed (and the 2986 seems to be out of stock in lots of places), not sure exactly what the difference between the 2786 and 2986 is.

https://www.rockauto.com/en/catalog/gmc ... lutch,6812

IIRC, the reference vehicle that I used for this was a 2005 Tahoe with the 4.8-litre V8 and tow package, which pointed to the Hayden 2986 as the severe-duty replacement.

As for the differences between the two, I have no idea. Going through Hayden's catalog and trying cross-reference searches isn't getting anywhere. I'm wondering if the 2786 may not have replaced the 2986 in the product lineup.

k9adv · **Posted:** Mon Aug 06, 2018 10:12 am

yeah, searching part 2986 on that Hayden catalog link shows "Part Not Found. Please modify your Search or provide Feedback with the link provided below.".

2786 is found.

And using your stated search parameters, 05 Tahoe , 4.8 , w/ towing shows 2786 now.

And....it seems using Hayden 2786 and the AC Delco 11 blade fan in RockAuto link below, this upgrade can be done for under $100, and even less if you get the Dorman fan and bolts from Amazon. Hayden 2786 is about $47 on Amazon prime right now.

https://www.rockauto.com/en/partsearch/?partnum=620602

casm · **Joined:** Sun Jan 29, 2006 5:05 pm **Posts:** 694

k9adv wrote:

yeah, searching part 2986 on that Hayden catalog link shows "Part Not Found. Please modify your Search or provide Feedback with the link provided below.".

2786 is found.

Yep - and I just double-checked my Amazon order history; it was definitely the 2986 that was purchased.

Working from home today, so had a few minutes to call Hayden's support line (866 502 0068). Per the fellow I spoke with there, the 2986 does not appear in their internal system either - but the 2786 does.

He couldn't say what the differences between the two are because he wasn't able to pull up info on the 2986 to compare with the 2786, but he did confirm that the 2786 is correct for the 2005 Tahoe with the 4.8 V8 and tow package.

No idea what's happening here, and I'm kinda wondering what the fan clutch actually is that I've installed on the KJ. If the 2986 flakes out on me anytime soon, I may just replace it with the 2786 and see what happens.

GordnadoCRD · **Posted:** Mon Aug 06, 2018 12:13 pm

2986 fits a HD 3/4ton chassis with 6.0L. Can't remember what years but it's not current.

k9adv · **Posted:** Mon Aug 06, 2018 12:16 pm

GordnadoCRD wrote:

2986 fits a HD 3/4ton chassis with 6.0L. Can't remember what years but it's not current.

Hayden no longer offers the 2986 at all. it is no longer listed in their catalog and all vehicles that had it as recommended part number by Hayden are now showing 2786, so it appears to be a part number change/recommendation overall.

Any 2986's available online (which are few places (most showing out of stock) must be remaining stock being sold off. The price difference between the 2786 and remaining 2986s is $15-20 less for 2786.

GM Radiator Fan - What I discovered of interest to all

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