Updated Thermal Control Valve

SuperOldSchool

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I plan to do this on my 8l90. Does the kit come with new cooler line o-rings? I have the plate and bolt style thermostat.

If not, Anton elbow tha part number on those 2 o-rings? I was not able to search those on GM Parts Direct or other sites with the expanded parts diagrams.

Thanks!
 

Rygrego

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I plan to do this on my 8l90. Does the kit come with new cooler line o-rings? I have the plate and bolt style thermostat.

If not, Anton elbow tha part number on those 2 o-rings? I was not able to search those on GM Parts Direct or other sites with the expanded parts diagrams.

Thanks!
You should be able to reuse the O-rings, I did with no problems.
 

SuperOldSchool

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Maybe, but after 100k miles and 7 years I would think they are a lil deformed.
 

Prospect62

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Thought I would increase our knowledge base by closing this out. I did purchase the 86774933 for my truck. Mounts to the transmission fine, but body of the unit has a slightly different angle where the lines mate with the unit, and it did not want to seal properly. My solution was to swap the new thermostat into the old housing.


Brad I think what happened in your case is you mistakenly bought the valve for the 6-speed when you have the 8-speed tranny. You need part #13511137, and that would explain why your lines didn't match up just right. It's weird though, there is no mention of the 8-speeds in the TSB. But if you look up the valves in the GM parts database, there's a clear distinction between the 6 and 8 speed valve.

Just my theory. I'm seeing numerous part numbers listed for the thermal bypass valve depending on application, but the 86774933 seems to be the right one for 6-speed equipped 1/2 ton trucks 2016-2018 (which all have steel cooler lines).

2019-2021 trucks have aluminum cooler lines. The correct part number for the updated valve is 85563685, again for 6-speed (MYC, MYD) equipped trucks only.

The correct "seal" or gasket thing is 23135703 across all applications.

The 2015 and older trucks use the quick release style lines and aren't even mentioned in the TSB. I'm not sure what you guys do.

I don't know. Seems the problem doesn't affect the 8-speeds, or at least GM doesn't think it does.
 

Tall56Dog

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Question for the guys that have done this. I replaced the stock Trans thermal valve with the new GM part #85563685 valve about a month ago on my 2020 Tahoe with the 6L80E.

I think it takes longer for the trans to get hot, but it still gets to around 195 degrees sometimes.

I was thinking that the updated valve would not allow the trans to get that hot seeing as it is set to open around 150 degrees.

The more I think about it though, even though the new valve is set to open at a lower temp, the trans can still get much hotter depending on the ambient air temp, and how hard the trans is working.

My question is, for the guys that have made the switch, are you noticing the same thing, or does your trans temp stay at about 150 degrees all the time?

Just trying to figure out if this is normal, or if maybe the new GM valve I bought is defective?

Thanks
 

greenhornet

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My 2015 Tahoe LS stays around 70 deg.C=158F. If it gets hotter than that the valve would be wide open and you may need a larger ext Trans.cooler.
 

Rygrego

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Question for the guys that have done this. I replaced the stock Trans thermal valve with the new GM part #85563685 valve about a month ago on my 2020 Tahoe with the 6L80E.

I think it takes longer for the trans to get hot, but it still gets to around 195 degrees sometimes.

I was thinking that the updated valve would not allow the trans to get that hot seeing as it is set to open around 150 degrees.

The more I think about it though, even though the new valve is set to open at a lower temp, the trans can still get much hotter depending on the ambient air temp, and how hard the trans is working.

My question is, for the guys that have made the switch, are you noticing the same thing, or does your trans temp stay at about 150 degrees all the time?

Just trying to figure out if this is normal, or if maybe the new GM valve I bought is defective?

Thanks
 
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