4L80 temp

Bob G. · December 8, 2003

I have a 1500HD with the 4L80 transmission. I drove 455 miles today from PA to VT with outside temps around 22 degrees F all day and the transmission temp gauge barely budged over 100 degrees. It finally went to 120 when using 4 wheel drive and 3rd gear in the Adirondacks. It usually runs around 160 degrees in the summer. I didn't notice that it did this last winter.

Also, I noticed for the last month that when the temps are in the 30s or less, the tranny won't shift into OD until it is at 100 degrees. Is this normal?

Bob G.

BlackSilver · December 8, 2003

Your tranny has no thermostat like your engine, and will run much cooler in the winter than in the summer.

Shaners · December 8, 2003

Mine runs cool also in the winters here in PA unless I'm towing something.

It's normal for the tranny to stay in 3rd until there is some heat in the motor.

tbyrne · December 8, 2003

Mine does the same thing in the winter unless I let the truck idle for awhile or go into 4WD. It stays just over 100 if I jump in and head straight for the highway. I'm going with synthetic fluid this week so that will help it run a little cooler.

Tom

Bob G. · December 8, 2003

Thanks for the responses. Sounds like my tranny is acting normal.

Bob G.

gave20 · December 9, 2003

Mine does the same thing criusin down the turnpike it lays at 100 in town it rises alittle. I was always told to much heat or not enough wasn't good for a transmission I guess you could put some cardboard in fornt of the cooler to make it run hotter too.

JimWilson · December 11, 2003

Yours is running a little cooler then mine, and I use Mobil 1 synthetic in my tranny. Hmm...

The OD thing is normal though. GM programmed it that way, so just take it a little easier for the first few miles on the highway (until OD kicks in). That's what I do anyway.