a trans question

[E2360]

Reading this forum and other sources of information have givin me enough knowledge to ask really odd questions.



First, I know that the best place to measure trans fluid temps is in the line comming from the trans to the cooler to capture the temp of the fluid from the torque converter. Now, is this still true when the converter is locked up? I have been towing about 10K a thousand plus miles and temps have been steady at 180 degrees. Just wondering if this is a valid temp for the hottest fluid when the TC is locked up.



Also, when stopping after a haul. Is it better to idle in park or neutral? I read one place that the fluid only circulates when in neutral and another that said does in park also. Iam sure someone here will know the REAL answer.



Thanks

 

[LRutigliano]

Even with the TCC locked up, the hottest fluid temp will be in the line going to the cooler.



With that said, I have my sensor mounted in the pan because I wasn't sure how the sensor would get a good ground (DiPricol's are 1 wire) with the rubber hose in the cooler line. Also, the cooler line from Geno's was more than I wanted to spend.



On a good hard pull up a 6% grade at 55mph with the 5er, my gauge reads 140F. However, if I drive with the 5er in stop-go traffic, it will get to 170 to 180F. Attempting to park the trailer perfectly at the campgrounds (back and forth... ), it has climbed to 190F.



Unless you have an aftermarker VB or have modified your own VB, the fluid only circulates when not in PARK. Obviously, be sure to set your PB if idling in NEUTRAL with the trailer in tow.

 

[cerberusiam]

Just wondering if this is a valid temp for the hottest fluid when the TC is locked up.



Also, when stopping after a haul. Is it better to idle in park or neutral?

Yes, the output line to the cooler is the best place for both max temps and essentialy trans temp when the TC is locked.



When the TC goes into lockup the fluid fluid is routed to the cooler at whatever the line pressure is, 55-180 psi depending on the VB setup. In lockup, you are seeing pan temp plus what little is added by pump pressurization and routing thru the VB, 10-20 degrees I am seeing at the max.



When the TC is unlocked, you are seeing max temps created by the fluid shear and that is what you want to keep an eye on.



Unless you modify the VB you will NOT get fluid flow in park. After pulling hard it is a good idea to idle it in drive for a bit until things cool down. Extended idle times in park are not a good idea with the stock components. Period.



Cheers