Transmission service, changing bypass thermal valve, part numbers?

[tom3]

Posted in wrong forum previously.
Getting ready to drop the pan and change lube and filter on the 2019 Tahoe transmission. Like to change to the lower temp. thermal bypass thermostat valve while I'm into it. I see the original lower temp valve no.86774933 is "unobtainum" these days, searched all around. Did get a hit on a superceded part number 85585333 in place of this. Can't find any info that that substituted part and I wonder if it does fit and work like the earlier piece. I wonder why they changed the part too. These things sure aren't cheap so I want to get it right the first time. Anyone up on this deal?

 

[Rygrego]

86774933 is the only number I have seen and used, but that was over a year ago. Here is the TSB: https://static.nhtsa.gov/odi/tsbs/2021/MC-10207911-9999.pdf

 

[Bigkevschopshop]

Just pop yours out and do this to it, the updated ones are not much different than the stock ones. This kit is pretty easy to install and keeps mine at 150 deg year round.

https://superiortransmission.com/product/superior-stl010/

 

[Thrust]

I flipped the pil on mine and it runs below 150F.

 

[tom3]

I did order the actual 4933 valve, got the 5333 replacement for that one. Label shows it with both numbers. I guess I'll have to hook a couple hoses to it and heat it up in some water to find out if it's actually the lower temp unit or a scam to sell parts. Don't see the "70" stamped on it anywhere like the original replacement piece shows. It sure seems to be hard to buy stuff - correct stuff - these days. We will see......

 

[Rygrego]

I did order the actual 4933 valve, got the 5333 replacement for that one. Label shows it with both numbers. I guess I'll have to hook a couple hoses to it and heat it up in some water to find out if it's actually the lower temp unit or a scam to sell parts. Don't see the "70" stamped on it anywhere like the original replacement piece shows. It sure seems to be hard to buy stuff - correct stuff - these days. We will see......

The 70 stamp stands for 70C = 158 degrees F. If that is not there it is not what you want.

 

[tom3]

Did a heat test on the substituted temp control valve and it does start to open at 70 deg. Cent. - or 160 deg - seems full open at 80 deg C - or about 180 degrees. Looks externally the same. I see three part numbers for this same valve, must be some sort of upgrade or maybe an internal mod. for some reason. If I lived in a warm climate I'd just flip it and go.

 

[RobH]

I got a GM reman 6l80 put in this week. I told the service advisor I wanted the service bulletin bypass valve. I was charged $88 for part # 86774933. I don't know if they happened to have some in the back or what.

A December, 2021 copy of the service bulletin is attached below. There may be a more recent copy of the service bulletin.

Why I was charged for it I do not know. The transmission comes with one. Are they still installing the 90°C valve in re-manufactured engines? Or did they charge me because I knew enough (due to this forum) to ask for it.

The temps used to be 185°F±. This afternoon in 90°F ambient temp, the transmission temp was 150°F±1°F.

Here is a link to my sick transmission thread with the help I got from others on the forum.
"https://www.tahoeyukonforum.com/thr...n-p0700-b2aaa-p0741-b2aaa.141132/post-1776149"

FWIW and YMMV.

Best wishes to all. Rob