Exhaust crossover under the rear of the pan shouldn't make any difference cruising down the highway. I didn't find anything with the temp gun other than cooler on the bottom of the pan and 2XX* on the sides when I was logging 2XX*.

 

Ya, exhaust isn't causing your issue unless return line is on it.

 

Well, I feel like a tard...

Trans temps by gun:

Converter:
180 by flywheel to 195 near front pump

Trans pan: 130-160* 160 being close to the exhaust

Lines:
Supply to cooler: 116*
Return after cooler: 109*

Trans temp was reading 205*

As soon as the rain lets up I will do some more testing, but looks like I will be dropping the pan to replace the sensor.

EDIT: Temp gauge got hotter and temps were higher so may not me the problem.... Can't remember all temp numbers highest was 240 on TC

 

Are those running temps or engine off?

 

Had the same issue with the 4l80 I swapped in. Same exact temp readings at the 40k in and out. At first I thought I had found the issue with dirtdobbers building a nest in my new 80e lines but that wasn't it. Temp would climb slowly, If I kept it at 60mph it would hover about 220... With a 90 deg ambient temp. Make a 2 month long story short, there was a crack in the center support and the pump was replaced completely from another unit. So I'm really not sure which was the culprit but it works flawless now. Gilbert @ Ace def had his work cutout on this 80e build!

 

Engine running


I hope that is not the case, I got a temp sensor I can swap in and hope like hell it fixes it. What year of trans did you have with the center support crack?

 

It as a 2001 model

 

What is acceptable for converter slip? (RPMs)?

 

0 when locked. Unlocked it is going to depend on engine RPM, torque, stall speed, etc. More slip when unlocked = more heat.

 

I'm seeing 120rpms at 50mph, 150 at 60, and 175 at 70