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Does 8L90 transmission with 2.7 turbo have a thermal bypass valve?

Interleukin6
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Interleukin6 Enthusiast

Interleukin6

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Posted (edited)

Finally, I dropped the pan today. I really appreciate all who posted good info on my previous thread, especially foundupot, newdude, & Gangly, which were a huge help!

One thing I want to share… I had almost 2 qt+ fluid coming out during the temperature level procedure after putting 7.6 qts in (I know 8L90 takes 7.4 qts for pan drop but I did 0.2 qts overfill to make it easy for the level check). I was shocked and then measured how much old fluid was taken out when I dropped the pan. It was approximately 5 qts+ (yes, I spilled it some but not that much causing this difference), which should be around 7.4 qts. This is my first transmission fluid & filter change at 45K miles. I haven’t had any transmission issues. OMG!!!! I am not sure what was wrong…. I did everything exactly what all good folks told me… confused.

Sorry for the long talk, just want to confirm… Does anyone know 8L90 (MQE) with L3B has a thermal bypass valve or not? Newdude previously said it doesn’t but again just want to confirm. If yes, I have to reach TFT above 194F then cool down to 95-113F to check fluid level…  It takes a quite long time to cool down and I am also a little bit worried that more fluid will come out or I will need to put more fluid in…. If yes AND I just do level check 95-113F without previously reaching 194F, will it cause serious damage to the transmission? When I asked dealer, they said it would take 2 hours for transmission fluid & filter change… but I don’t think TFT can drop from >194F to 95-113F that quickly (someone said it took all day). If not, I can stop here!!! Thank you.

Edited by Interleukin6
newdude Senior Enthusiast

newdude

Posted
Posted

I honestly don't believe the 2.7 8 speed does. 

 

The 8 speeds behind a V8 do and its externally mounted similar to the 6L80. 

 

The MQE, if it does have one, its internal, but I don't believe they have one.  The cooling operation for it is quite different too as it does not have a front mounted cooler or aux cooler, rather it uses an oil to water heat exchanger brick, which is why the temps climb fairly quickly but also stay very regulated compared to engine temp.    

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SilveradoRST Enthusiast

SilveradoRST

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Posted
35 minutes ago, newdude said:

I honestly don't believe the 2.7 8 speed does. 

 

The 8 speeds behind a V8 do and its externally mounted similar to the 6L80. 

 

The MQE, if it does have one, its internal, but I don't believe they have one.  The cooling operation for it is quite different too as it does not have a front mounted cooler or aux cooler, rather it uses an oil to water heat exchanger brick, which is why the temps climb fairly quickly but also stay very regulated compared to engine temp.    


Good info.  

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