screeching/whine noise engine any ideas?

[bowman818]

I have a screeching or whining noise I can't figure out on my early 99 7.3. It almost is comparable to normal turbo whine, but with slightly metallic sound.

It is coming form the engine compartment and is totally intermittent. Sometimes I won't hear it for 10 miles and then sometimes it will sound off every 10 seconds to 1 minute. It seems worse under heavy load and turbo boost. I am guessing it is turbo related, but not positive.

Any info would be appreciated.

[STIgone73]

How loud of a noise is it? Are you sure it's metallic? Have you ruled out your serpentine belt or tensioner yet? When I first got my truck (used with 146k on it) it started making a similar noise. Narrowed it down to the tensioner and replaced and everything was fine.

[bowman818]

I just replaced the tensioner recently. I think it is actually the a/c clutch.

[ttyR2]

If it is, check the a/c clutch gap. May be too big.

[TonyPeebs]

Did you find the issue?
Mine was making that kind of sounds and it was the trans pump starving for oil....

[bowman818]

Update
long overdue update: My neighbor used to be field fleet mechanic on these trucks and he said to spray electric parts cleaner on the a/c clutch to clean it and the noise would probably go away. So far... after 2-3 cleanings on the truck the noise is gone.