2007 Workhorse 8.1 noise when fan kicks in

[kernst52]

I posted about this problem a couple of years ago, a rattly noise on hot summer days of around 100 degrees when climbing steep hills or driving in town after coming off the freeway. We have been going on several trips since without too much problem. Experienced it again at 6 p.m. on a hot day coming off the freeway and putting around town. When the fan clutch kicks in there is a loud, and I mean LOUD SCREECH like metal on metal. We got home by traveling at night and of course had no problem.

I held the water pump pulley still and tried to spin the fan and there seems to be the right amount of stiffness. I took off the belt. There seems to be no looseness with water pump and fan shaft.

I did notice a very slight looseness when trying to wobble the tensioner pulley sideways back and forth - very slight. Could this be the problem all along?

Any ideas would be greatly appreciated.

Thanks, Ken

[Ray,IN]

I think you found the loud noise, replace tensioner pulley. Vehicle mfgrs and accessory drive belt mfgrs. recommend replacing both at the same time anyway.
About 10 years ago I discovered there is a go/no-go wear gauge for replacing multi-rib belts

[Arch Hoagland]

I've had my tensioner pulley replaced three times over the years. Very common problem.