This may be a really stupid question to those who know, but, do the automatic allisons have a clutch fan? Ive heard the guys that tow heavy talk about hearing theirs come on. I listen pretty closely to whats going on with my truck and if my clutch fan has ever come on I have not heard it, or known that that was what I was hearing. I also dont tow heavy often if at all.

Mine does. If it's very hot out and the AC is on and the engine is idling for a few minutes....typically you can hear the fan ROAR as you get on the accellerator (you won't hear it at idle from inside the vehicle). Once enough 'cooler' air comes thru the radiator the fan will disengage.

As long as the truck is moving around, I don't hear the fan at all. Only after a stop or after idling a while.

Typically the fan is engaged on cold starts as well but typically disengages pretty quickly.

DEWFPO

jmg343, are you asking if there is a fan on the transmission itself? If so, then no. What people are talking about is the clutch on the radiator fan kicking into "high gear". It is not a true clutch, but rather a viscous coupling. There is a temp. sensative valve that lets more fluid in when it gets hot. This causes the fan to spin faster. As the temp decreases, a valve opens to let fluid out of the chamber and the fan spins slower.

I also dont tow heavy often if at all.

Northern CA, case closed.

being born and raised in upstate NY and only a resident of Northern California for a short time, could you explain what this means?

side note: northern california, and the rest of the state as far as Im concerned, BLOWS!!!! except for the off-roading and dirtbike areas! but the drivers...they blow the hardest
Northern CA, case closed.

I was referring to the ambient temps, not the kind that bring on fan activity. And you are not towing heavy

Not referring to anything else. sorry for the kurt response.

Killer, you may want to expand your answers just a bit to avoid confusion like that. That was pretty funny though.:D

And for your information we have been at a hundred degrees for about two weeks now;)

Birken

no problem killer, just wasnt sure.

I dont know where birken is from but here too. Im about an hour north of San Fran and 95-105 degree days arent uncommon at all. We also tow up some nasty hills, dont know what % grade but Id reckon 6-7% easily. Theyre long and windy as a bicth too.