Transmission Cooler Line Pressure

[Buick Beginner]

Folks,
Just wondering, does anyone know about how much pressure the tranny cooler lines are holding? I need a high and low range for a little experiment I'm doing. I think the highest the pressure goes in the cooler lines is like 150 PSI but I'm not sure about what the lowest safe pressure is, 20 PSI, 40?? Thanks for the help, - BB

 

[WE4]

I can tell you Exactly

We run a cooler line pressure gauge in the test car. I note Highest pressure seen on the test sheet we furnish. I can tell you it is directly related to line. Follow me here, It is normally not much as the fluid is flowing to an open source. The return feed is the lube circuit and enters the trans thru the od center support. It then splits and feeds forward thru the input shaft and backward down output shaft. from there it gravity feeds back to the pan. Now under hard excel, can you see way it has trouble with scavenge back to the pan as far as fluid level in pan? Thats where the deeper pans with more capacity come in. Now , in a trans that has higher line pressure , say 140 at idle, will have as high as 50 psi under acceleration. A stock brf say will have 70 psi line pressure at idle and will flow about 10 psi. When the converter locks it will run between 30-40 psi (higher line) and 10-20 psi in a stock BRF in the cooler line. If ever you see higher than 65 psi or so, in the cooler line, something is not right. I see this every day as every Trans we build is tested and has this reading on their test sheet. Those of you who have there sheets handy , post as to what yours were with relationship to line pressure. Should be interesting if some will step up.

 

[Buick Beginner]

Good Info!

Bruce,
Thanks for the great reply, the info really helps! - BB