[updated:LAST EDITED ON 08-Jan-03 AT 02:13 AM (EST)]I've had this funky, intermittent, metallic scratchy noise coming from my motor. At first, I thought it was the P/S pump, but I finally grabbed a length of hose and found that it appears to be coming from the fan pulley (I think the clutch might be bad) When I say intermittent, I mean that it's guaranteed to be there when the truck's been sitting (overnight), but there's no pattern to the actual noise. The noise goes away once the engine is at operating temp.

I'm thinking that the fan clutch ate itself - anyobody else had experience with this?

Thanks in advance!

XXL

 

[updated:LAST EDITED ON 09-Jan-03 AT 09:22 PM (EST)]Yes... I've noticed similar issues on my 99 Expy 5.4L. I too am thinking fan clutch for at least one of two noises... I've got a couple of different sounds coming from there. I would describe the first as a high-pitched metallic sound, only when I've just started up and particularly when it's cold out.

Within first minute or two, I notice it primarily when the engine is cold, and it is most pronounced/audible/louder when RPMs suddenly change from higher to lower (i.e., when you first put it in reverse to back out of garage, or on the first few 1-2 shifts)... It's never really loud, but noticable.

2nd noise is more of a scraping, a pulsating scraping that is definitely audible when cold... It tracks in frequency with engine RPM, is more constant but also goes away after engine warm up. This one sound to me like perhaps water pump or alternator though... Maybe related though? I'll investigate more as time progresses...

Neither sound is terribly pronounced but definitely exist and have shown up just this winter... Didn't hear these prior to this winter.

 

Check the idler pulley and tensioner pulley. I have see issues with lack of lube to the bearings due to cold weather, causing high pitch squeel on cold start.