Engine/Transmission (1998.5 - 2002) Fan clutch lock-up not!

[DWest]

Last week on a long haul from Wisconsin to Colorado pulling a 7x18 trailor at 7000lbs I had no problem till we started to climb I-70 out of Denver. The temp gauge which hadn't budged off 190 went to 240 instantly. I was towing in OD and the fan clutch wouldn't lockup. So I pulled over and let it cool down at idle then proceeded on in third gear, the clutch would sort of lockup but not fully as it was'nt that loud. Sometimes it would kick in at 210 then the next hill it would let it get to 220. Is this a common problem. I've hardly ever pushed this truck hard enough to make the fan clutch lockup , did it fail because of lack of use or is it a week spot in the motor like the lift pump? DW

 

[bmoeller]

Originally posted by DWest

Last week on a long haul from Wisconsin to Colorado pulling a 7x18 trailor at 7000lbs I had no problem till we started to climb I-70 out of Denver. The temp gauge which hadn't budged off 190 went to 240 instantly. I was towing in OD and the fan clutch wouldn't lockup. So I pulled over and let it cool down at idle then proceeded on in third gear, the clutch would sort of lockup but not fully as it was'nt that loud. Sometimes it would kick in at 210 then the next hill it would let it get to 220. Is this a common problem. I've hardly ever pushed this truck hard enough to make the fan clutch lockup , did it fail because of lack of use or is it a week spot in the motor like the lift pump? DW

I suspect the t-stat could be sticking shut. It would prevent coolant from getting to radiator, thus the fan wouldn't kick on.

 

[MCummings]

I suspect a broken thermostat also.



The Fan CLutch should be locked up at 220, that's for sure. At 2,000RPM, the fan won't be THAT loud, bump up the RPM to 2,600RPM, and the fan should ROAR.



Merrick Cummings Jr