keep the Allison cool

GMC8.1 · July 2, 2003

I have noticed that when my tranny temp gauge gets near 200 deg, the cooling fan kicks on and stays on. It mostly comes on in stop and go driving, but does not go off. I was wondering if anyone has any tricks to keep the tranny temp down so the fan doesn't constantly come on and kill my power and mileage?

Bluedog · July 3, 2003

Try putting it in T/H mode... Locks up the converter in 2nd and 3rd. That seems to make ~25 degree F difference, especially in stop and go.

Mike

GMC8.1 · July 3, 2003

Thanks for the reply Mike,

I will try putting it into T/H mode and see what happens, but will that hurt the tranny if it is run that way all the time?

TomEllis · July 3, 2003

Thanks for the reply Mike,

, but will that hurt the tranny if it is run that way all the time?

It will not hurt the transmission, All the T/H mode does is change the shift points and torque converter lockup points.

The fan clutch is not locking because of the transmission, however, it is locking up because of engine temperature. With higher temperature, more air flow is needed through the radiator.

Try the T/H mode anyway and see if it helps.

Good luck,

Tom

GMC8.1 · July 3, 2003

Initially, I believed it was the engine temp also, but as I kept watch on both gauges I saw that the engine temp gets to about 205 and stays there but the fan doesn't necessarily come on and never once has it gone above 210. It appears that the fan comes on when the tranny reaches 200 or even 190 which led me to believe the transmission was the cause. I could be wrong, it happens alot.