Originally Posted by
DmaxMaverick
Welcome aboard!
As Gary suggests, definitely check/clean the cooling stack. If the air is blocked, the fan clutch won't engage. If it's clear, then the thermostats and/or fan clutch is the next suspect(s).
That's interesting, I had thought that the fan clutch would kick in with / without a clogged radiator... Damn...
So that was another clue, also I had literally never heard it kick in so I had no reference for when it should / what it would sound like.
I'll have to find a big hill around here and floor it all the way up to see if my fan clutch now engages. On the way back from San Francisco I did floor it all the way up into the mountains with a 9500lb trailer but I don't think I heard it... It is however a very loud truck (less loud now that I have a muffler again). Could also be that the truck just never got hot once it had a damn radiator.
GMC Sierra 2500hd 2004.5 now with ARP studs