4L80E getting hot.

[dun ploughin]

I've got a 2006 silverado with a 4L80E.
Yesterday while on the freeway the transmission temperature rose to 250*.
I got off the freeway, checked the fluid, etc the fluid level was good and didn't seem to smell burnt. I let it cool down for about 20 minutes and turned the key on and it was still hot. I felt the cooler and it wasn't hot. After the transmission temperature got back below 200*, I started driving again (not on the freeway). It got back up to 250* after a few miles.
This morning, it took about 1/2 hour, maybe longer of city diving to get above 200*.
Could there be something causing the fluid to not circulate through the cooler?
While I was sitting waiting for it to cool down, I called my mechanic. His guess was clutches.
It shifts smoothly and doesn't slip.
I'm hoping some transmission guru has an answer.
I haven't checked for codes, or actually checked the pan temperature when it was hot.

 

[Bebop]

Are you sure the temp sensor is good ?

 

[dun ploughin]

Are you sure the temp sensor is good ?

I'm not sure of anything.
I had a chat on the phone with an old transmission rebuilder. Without scanning, checking pan temperature or anything he thinks the torque converter isn't locking up.
He said it didn't sound like a clutch pack.
He wouldn't have time to work on it for several weeks, but thinks he could at least diagnose in the near future.
There's also a chance the issue is electronic.
The truck is rusty and has almost 260K miles on it so I'm probably not rebuilding the transmission. I'm hoping the fix is under 1K.
At the moment, its the only running work truck I have.
Time to unload some of my unfinished projects to make room for something a little more reliable. This truck has been a workhorse so I'd like to keep it as a spare.

 

[Snoop dogg]

You can put a harbor freight infrared thermo on the pan to get an idea of temp.

 

[dun ploughin]

You can put a harbor freight infrared thermo on the pan to get an idea of temp.

I was thinking of that. I forgot where I put my inferred thermometer since I quit having to worry about snow and ice.

 

[M92PV4U]

torque converter isn't locking up.

That was my guess.

 

[Rennat_2006]

Can almost gaurantee it is the torque converter. Dirty or messed up mass air flow sensors on those 6.0/4l80e trucks smoke their converters real quick too, ive seen it a few times.

 

[Bebop]

I'm not sure of anything.
I had a chat on the phone with an old transmission rebuilder. Without scanning, checking pan temperature or anything he thinks the torque converter isn't locking up.
He said it didn't sound like a clutch pack.

You should be able to force feed the solenoid and make it lock up if you have a bidirectional scan-tool.

 

[dun ploughin]

Can almost gaurantee it is the torque converter. Dirty or messed up mass air flow sensors on those 6.0/4l80e trucks smoke their converters real quick too, ive seen it a few times.

Interesting.
It hasn't been in a shop for service for quite some time, so a scanner hasn't been plugged in.
I've been too damn busy to have it down. Every job I've done this year has added stuff, hidden stuff, etc. Its been a scheduling nightmare.

You should be able to force feed the solenoid and make it lock up if you have a bidirectional scan-tool.

Thanks for advice. I'll pass it along to my mechanic.

 

[dun ploughin]

With the information you guys have given me, I've done some googling. It sounds spot on.
From what I read, it also makes sense that driving at low speed, around 30 MPH the temperature stays within reason.
I'm glad I got off the freeway and took the slow road when I did. I was pulling a 3000# trailer.
I did notice now that there's a little discoloration in the fluid. Hopefully the damage is limited to the torque converter.

 

[arse_sidewards]

Were you in 4th with the TC unlocked?

There's a reason all those old school 4spd autos came with an "OD off" button of some sort.

A 4L80E should be able to tow shit around using the first three gears and no lockup same way an old TH400 would have.

 

[dun ploughin]

Were you in 4th with the TC unlocked?

There's a reason all those old school 4spd autos came with an "OD off" button of some sort.

A 4L80E should be able to tow shit around using the first three gears and no lockup same way an old TH400 would have.

You hit the nail on the head. I'd just gotten on the freeway and drove around 70 MPH (the speed limit on that stretch is 60) for I'm guessing 10 miles when it started to heat up.
Because of the age, mileage and deferred maintenance, I've been avoiding 70 MPH speed limits, because naturally, I'd be driving 80 MPH.

 

[JD Mark]

because naturally, I'd be driving 80 MPH.

You're such a rebel.

 

[dun ploughin]

You're such a rebel.

That's why I'm here....