Good video on the 8 speed ZF fluid

[Wild one]

This video is a good one to watch in it's enterity if you're doing a fluid change or tranny swap on your 8 speed truck. It mentions the fact that the tranny should be warmed up past 160 first to make sure the cooler bypass has opened and filled the tranny cooler,which is not covered in the Chryco procedure.

 

[Kap1]

Thank you for posting this video.

I'm trying to understand though - how does this "valve" relates to changing 8 speed fluid on our Ram's?

Do we need to do the whole process, and then drive around to get trans fluid hot, and then check again to make sure level is correct?

Or what the best way would be?

 

[crash68]

I'm trying to understand though - how does this "valve" relates to changing 8 speed fluid on our Ram's?

The thermostatic block ion those transmissions is part of the TMU on the side of the Ram truck variants of the transmission. The TMU also has engine coolant piped to it for faster warm up. There is a three way valve that directs coolant through the TMU when not needed by the cab for heat.

The TMU is the square thing on the side.


I have to wonder how much if any fluid drains out of the transmission cooler when the bypass is not sending fluid to the cooler in the condenser.