2022 Trans temp...

[hollywoodsle]

On 4/14/2022 at 4:54 PM, Wxman said:

Hey all.  Based on my VIN gmparts direct suggests 85547828 instead of 86774933.  I am asking them to confirm the '828' part is 158F valve.  Anyone have insight on this?  Local dealer was blank stares when I started asking questions about the TSB and TBV temp change.

 

Thanks

7828 is correct for 2500, 4933 is for 1500 2016-19LD.

 

[Wxman]

Got it now, thanks.

Finally found a copy of the Dec TSB with all part numbers.  GM Parts Direct was apparently incorrect when they told me the 7828 valve would be the same as original for my VIN.  That doesn't agree with TSB and my valve does not have any '70' markings.

 

Thanks all.

[Wxman]

Just a follow up to close this out.  I ended up having dealer do the TSB and went ahead with a fluid/filter change as well.  Always like to do the first one early anyway.

Dealer had no problem doing the TSB - (After I showed them a printout and a little discussion with the advisor.)  Ordered the parts ahead of time so they would be ready for the appointment.

Looks like the work went well, new valve has the '70'.  It was the 85547828 part number.  Temp looks like it is running 25-30 degrees cooler running around empty, 150-155 ish vs 180 ish.  Haven't towed yet to see if it runs cooler under load as well.  Happy with all that even though appointment was a nightmare.

 

Appointment to drop off on Tues.  Dropped off at 0715.  Called at 1600 to check as my ride needed to leave.  Hadn't been looked at yet.  "Hopefully in the morning".

Got a call about 1400 Wed, "You are next in line, but I didn't realize it was a Duramax when we checked it in."

?????Convinced advisor it was gas and they could proceed.????  Still didn't make the cut to get worked on Wed.

Finally at lunch time Thurs the work was completed.  And they wonder why I don't let them do oil changes, etc.

Ridiculous!  Happens I was working at home this week and I wanted this work complete before leaving on a camping trip Fri.  Still, probably won't be darkening their service door again.

[Black02Silverado]

12 hours ago, Wxman said:

Just a follow up to close this out.  I ended up having dealer do the TSB and went ahead with a fluid/filter change as well.  Always like to do the first one early anyway.

Dealer had no problem doing the TSB - (After I showed them a printout and a little discussion with the advisor.)  Ordered the parts ahead of time so they would be ready for the appointment.

Looks like the work went well, new valve has the '70'.  It was the 85547828 part number.  Temp looks like it is running 25-30 degrees cooler running around empty, 150-155 ish vs 180 ish.  Haven't towed yet to see if it runs cooler under load as well.  Happy with all that even though appointment was a nightmare.

 

Appointment to drop off on Tues.  Dropped off at 0715.  Called at 1600 to check as my ride needed to leave.  Hadn't been looked at yet.  "Hopefully in the morning".

Got a call about 1400 Wed, "You are next in line, but I didn't realize it was a Duramax when we checked it in."

?????Convinced advisor it was gas and they could proceed.????  Still didn't make the cut to get worked on Wed.

Finally at lunch time Thurs the work was completed.  And they wonder why I don't let them do oil changes, etc.

Ridiculous!  Happens I was working at home this week and I wanted this work complete before leaving on a camping trip Fri.  Still, probably won't be darkening their service door again.

Glad you got it take care of.  The town where I used to live is small and that dealer always took care of me.  I moved to a larger city and the dealer here is no where the same in customer  care.  So I took my truck back to the dealer where I used to live. It is only an hour and half up the road.

[mrjulian416]

Does anyone have a link to the actual TSB?  The only 21-NA-199 I can find is as a reference in an article and on various forums, but not a copy of the bulletin itself.

[Another JR]

First hit on duck duck go:

 

https://static.nhtsa.gov/odi/tsbs/2021/MC-10207911-9999.pdf

 

[sheath]

Had a hard slow pull through a tight winding mountain road with a 5th wheel travel trailer that weighs 14,600lbs (scaled weight).  Max trans temp was 232*F.   I've learned the fluid heats up faster than it cools.  But was impressed that the temperature stopped climbing at 232*F, even though the mountain climb continued for a mile or more.  This was repeated several times over the trip.  Engine temp never went above 210*F.  

This was as difficult a pull as I'd ever want to do.  Speeds rarely went over 30mph with a lot of 15-20mph travel, so there wasn't much air flow over the coolers other than what the fan could draw.  There was also a lot of heat coming off the asphalt. 

Overall, I'm happy with the results, and the confidence.

My truck was built Feb '22, so probably the latest updates are included. 

[Epsilon Plus]

I've been considering putting an aftermarket stacked plate/fan cooler on the truck. In Arizona often 110+ ambient temps, my truck has been hitting 216°F idling in the school pickup line with no air moving. My 22 has the 158°F thermostat. However, bypassing it will not solve the high temp from stand still issue.

 

Instead of tapping the factory lines and introducing a leak risk I'm considering deleting the radiator/stock tube/fin cooler and doing braided -AN lines direct to the cooler and back like I had on my GTO.

 

I wonder what the BTU/Hr removal rate of the stock cooler is. If anything, going through the radiator especially at rest is acting more like a trans heater than a cooler. I should probably leave the trans thermo in though so the fluid doesn't run too cold when it's 45°f ambient out and not 110+. The aux cooler fan thermo would be 180°F on.

 

Little disappointed in the stock setup that it can't handle 15 mins of idling without going to towing heavy up a hill temps. Blame the clutch fan at idle I suppose.

[Chuck FB]

On 8/21/2025 at 8:40 AM, Epsilon Plus said:

I've been considering putting an aftermarket stacked plate/fan cooler on the truck. In Arizona often 110+ ambient temps, my truck has been hitting 216°F idling in the school pickup line with no air moving. My 22 has the 158°F thermostat. However, bypassing it will not solve the high temp from stand still issue.

 

Instead of tapping the factory lines and introducing a leak risk I'm considering deleting the radiator/stock tube/fin cooler and doing braided -AN lines direct to the cooler and back like I had on my GTO.

 

I wonder what the BTU/Hr removal rate of the stock cooler is. If anything, going through the radiator especially at rest is acting more like a trans heater than a cooler. I should probably leave the trans thermo in though so the fluid doesn't run too cold when it's 45°f ambient out and not 110+. The aux cooler fan thermo would be 180°F on.

 

Little disappointed in the stock setup that it can't handle 15 mins of idling without going to towing heavy up a hill temps. Blame the clutch fan at idle I suppose.

That is the downside of a mechanical fan, an idling engine isn't turning the fan over fast enough for one thing and at least traditionally the bi-metal spring is set on the high side temp wise so does not lock up the fan clutch when one would desire it to. This reminds me of being in Death valley one day years back in July and by far the hottest temp I have ever been in ( I live in northern Alberta after all ) as it was 118 according to the part office. I was driving an older half ton pickup that I had swapped in the thicker core factory rad that fit the truck as it was meant for a 3/4 ton but I still had the half ton less aggressive fan ( the drive is not strong enough to drive the deeper fan of the heavier trucks ). However I didn't want to push my luck so was not using the air con at all and only the cab fan ... yeah, was I ever having fun LOL. So when I would come to the next place of interest I would turn the engine off as I knew it was not going to get any cooler sitting there idling and in fact because of the rad and not using the air con the engine temp actually stayed very good considering and I certainly was not pulling anything. When I pulled in at Bad Water I noted that most vehicles were sitting there running and were cars or mini vans and they all had electric fans and of course they were running their air con and every vehicles fan was howling at full tilt. 

 

Also when I had put the thicker rad in I had bought an aftermarket fan clutch hoping it would kick on sooner than the factory one but with testing of covering the grill at home to force the engine to warm up to kick the fan on, it was no better. So what I did being that it was a cheap unit anyway if I wrecked it I bent the bi-metal spring around at the end to change its effective length and preload and was able to get it dialed in to where it would kick on sooner but not at normal experienced operating temps as a locked up clutch is one power hungry/fuel hungry item when its not needed and would cause premature failure of all the pulley idlers and water pump shaft etc anyway. 

 

Now perhaps your clutch is engaging but with just sitting idling it may not have enough effect, next time its in that situation try slowly revving the engine up some to see if you can detect if the fan clutch is engaged by the sound of the fan noise. Your idea of adding an aux electric fan may be the the answer and hopefully the alternator has the ability to run it without undue stress at idle.  

[Epsilon Plus]

I had an Atomic Cool on my GTO. Low amp draw. Restrained a 4,500 stall in the same temperature environment.

 

Custom mounting will be the challenge. I'll have to fabricate something and sandwich it between the grille and condenser.

 

Edited August 23, 2025 by Epsilon Plus

[AndrewF]

On 8/21/2025 at 10:40 AM, Epsilon Plus said:

I've been considering putting an aftermarket stacked plate/fan cooler on the truck. In Arizona often 110+ ambient temps, my truck has been hitting 216°F idling in the school pickup line with no air moving. My 22 has the 158°F thermostat. However, bypassing it will not solve the high temp from stand still issue.

 

Instead of tapping the factory lines and introducing a leak risk I'm considering deleting the radiator/stock tube/fin cooler and doing braided -AN lines direct to the cooler and back like I had on my GTO.

 

I wonder what the BTU/Hr removal rate of the stock cooler is. If anything, going through the radiator especially at rest is acting more like a trans heater than a cooler. I should probably leave the trans thermo in though so the fluid doesn't run too cold when it's 45°f ambient out and not 110+. The aux cooler fan thermo would be 180°F on.

 

Little disappointed in the stock setup that it can't handle 15 mins of idling without going to towing heavy up a hill temps. Blame the clutch fan at idle I suppose.

I wonder if the PPE transmission cooler for the Duramax is a plug and play fit for the gas trucks as well.  Supposedly is 2X more heat removal. I guess it depends if the cooler lines into the grill end up in the same location with the same connectors. 

 

https://dmaxstore.com/products/ppe-transmission-cooler-for-2020-l5p

 

EDIT- the install guide has some good pictures to compare to.

https://cdn.shopify.com/s/files/1/0611/8539/2883/files/124066000_Trans_Cooler_v1.pdf?v=1671568035

 

Also could try the heat wrap on the exhaust piping nearest to the transmission as that seems to have helped some people. At idle I'd expect the most benefit.

Edited August 27, 2025 by AndrewF

[Chuck FB]

25 minutes ago, AndrewF said:

I wonder if the PPE transmission cooler for the Duramax is a plug and play fit for the gas trucks as well.  Supposedly is 2X more heat removal. I guess it depends if the cooler lines into the grill end up in the same location with the same connectors. 

 

https://dmaxstore.com/products/ppe-transmission-cooler-for-2020-l5p

That is a good question and would think they would mention it fits the gas application if it did fit. But there is a difference in the cooling fan diameter as far as I know and not sure if there is a difference in the temperature of when the diesels fan clutch engages but that would play into how effective stacking a larger cooler in front of everything else on the gas engine would have effect wise on the rest of the system. It seems to have taken GM years with the duramax to finally get some decent cooling, they should have thrown all that onto the gas engine ( probably takes more power though fan wise ) 

[AndrewF]

13 minutes ago, Chuck FB said:

That is a good question and would think they would mention it fits the gas application if it did fit. But there is a difference in the cooling fan diameter as far as I know and not sure if there is a difference in the temperature of when the diesels fan clutch engages but that would play into how effective stacking a larger cooler in front of everything else on the gas engine would have effect wise on the rest of the system. It seems to have taken GM years with the duramax to finally get some decent cooling, they should have thrown all that onto the gas engine ( probably takes more power though fan wise ) 

Yeah it is probably a long shot to be a plug and play fit without any modifications.

[Chuck FB]

5 minutes ago, AndrewF said:

Yeah it is probably a long shot to be a plug and play fit without any modifications.

That would be too easy of course !, never the less worth checking into. I was looking at Rock Auto to try and find some specs on the gas vs diesel rad thickness wise and there is a marked difference in core thickness and interestingly enough one of the aftermarket coolant rads they show for the gas they advertise as being somewhat thicker and a 20% higher cooling capacity. That shows they see a market for increased cooling of the gas engine. As to the engine driven fan, that is WAY bigger in diameter on the diesel and has more blades as well, just completely different as I thought it was. 

[bruceb58]

I tow a 6500# trailer and have never really seen the ATF temps go over 210°F and that was stop and go getting into Sequoia National Park up a steep hill. Outside temp was close to 90°F.

 

 

 

Edited August 29, 2025 by bruceb58