Once again I am having hell with the 4l80e. I burnt up the first one (got hot once and stayed at 210-240 rest of the time), intermediate clutches, sun gear, pretty much everything and ended up losing all gears. So had it rebuilt, 2nd gear sprag rolled, got it fixed and this one is running 210. I flushed the lines and bought a brand new trucool 40k.

I took off the line to the cooler, good fluid about 410ml, took off the line right after the cooler 400ml, and took off the return right at the transmission and got 420ml. This was all just starting it and shutting it off just as quick.


I remounted the heat exchanger lower so that the 40k is not blocked whatsoever. I drove it for about 15-20 miles at 60-70mph and once again it was about 205* when I pulled into the driveway. Yes, it is going into lockup. I am out of ideas and am really just ready to torch the damn thing.

Any ideas?

FTI 2800 triple disc full billet 10.5" converter

 

Do you have yours runnng through the rad? If so bypass it

 

And check to see if the Trucool is actually getting enough air. Grab the line going in and the line going out and see what the temperature difference is. If both are about the same then you've not got enough air going through.

 

Has the converter been checked since the last overheat ?

I only see max of 150* with my tru-cool.

If your gonna get out a torch go use it on a POS Kia or something , not your truck

 

Aux bypassed

Line is cooler on the return side

Converter was upgraded to triple disc full billet after trans was trashed, so yes it has been gone through.

I'm out of ideas.

 

I am running my lines through radiator and have my tru cool behind my heat exchanger and still run 145 on highway after a few hours in 90+ degree temps. Something else is going on, are you sure it's locking? Do you have tuning software or the ability to monitor input and output speeds of trans? You need to monitor it for slip. Any idea what your line pressures are?

 

are you using -an fittings on your cooler lines? if so, do you have the correct rear fitting? (its longer, and goes further in the trans for proper lubrication. that wouldnt explain the hot temps, though

 

Sounds pretty similar to mine as soon as I installed this particular 80E. First test drive I had the trans hot(over 266*) message pop up as I wasn't logging trans temp. When I logged it went over 200* after 10-15min of easy driving and just kept climbing. The TCC hold was weak and would start to slip if I went over 30% throttle.

The trans and converter went back to the builders and I got the trans back 6 months later. Reinstalled and it still had the same heat problem except that now the TCC held well. Input and output speeds matched, no slip logged. New Tru Cool(rad bypassed), 2 different TCs, swapped the temp sensor, 20* temp drop through the cooler, lots of fluid flow as you described with yours. Once hot, the temp did not seem to climb anymore if put in P/N, but never decreased when the engine was running.

 

So that's how your last truck burned down.. Lol

 

Yes, definitely sure it is locking you can feel it. Unfortunately I do not have tuning software, but I can data log with EFI Live Autocal. I think I might be able to do it that way. No idea on line pressures.

No -AN fittings yet, but do have the correct rear fitting with the extended nipple.

Definitely sounds exactly like my problem, I am going to get a temp gun and check it out in a little bit to make sure my temp sensor isn't the cause.

Yeah, do believe so! Waiting on the xmember so I can redo my exhaust!! LoL! I am thinking that might be causing a little bit of it because it is under the rear of the pan about .5-.75 of an inch.