By Brett Barton (Brett) on Wednesday, October 31, 2001 - 03:13 pm: Edit

When my truck warms up and is idling, I hear a high pitched squeal coming from under the hood. When I shut the truck off it stops, or if I speed up it disappears. I am thinking that it has something to do with the pulleys on the serpentine belt. I just replaced the alternator and the belt. Any ideas?

By Leslie N. Bright (Leslie) on Wednesday, October 31, 2001 - 03:17 pm: Edit

Put your head under the hood and isolate the source... is it coming from the front, or back further near the firewall? If back, might be a vacuum leak (I've got one, sounds just like you described but it's back further)... If from the front, can you tell if it's the alt, or the A/C, or the PS, or the waterpump pulley?

-L

By Bill Bettridge (Billb) on Wednesday, October 31, 2001 - 03:20 pm: Edit

It may be the idler/tensioner pulley - common bearing failure - see this Dweb

http://www.discoweb.org/discus/messages/9/5140.html?1004198356

Just replaced mine - bearing was <$10 at Napa

By Rob on Wednesday, October 31, 2001 - 03:23 pm: Edit

If you just replaced the belt are you sure you threaded it back correctly? Many people thread it incorrcetly and have this problem

By Rob on Wednesday, October 31, 2001 - 03:24 pm: Edit

More people spell incorrectly; incorrectly!

By Brett Barton (Brett) on Wednesday, October 31, 2001 - 03:27 pm: Edit

It appears to be coming from the front of the engine. I replaced the alternator two months ago and have the belt routed correctly. It is pretty loud and tough to trace. What should I look for to isolate it?

By Ron on Wednesday, October 31, 2001 - 03:29 pm: Edit

PS pump?

that would be my guess.

Get a long stick metal is preferred and listen to each component with the end of the stick touching it.

Careful not to get the stick caught up in anything.

Ron

By Bill Bettridge (Billb) on Wednesday, October 31, 2001 - 03:30 pm: Edit

Try a long screwdriver (or mechanics stethascope if you've got it ) on each bearing area - alternator, wp, idler pulley, etc etc - put the tip on the piece you want to check and the handle to your ear and you should be able to trace it down.

By Leslie N. Bright (Leslie) on Wednesday, October 31, 2001 - 03:32 pm: Edit

A very long screwdriver.....

Actually, a good shop should have an automotive stethoscope... earpiece like a doctor's, but on the business end instead of a flat disc there is a long rod. You can touch the end of the rod to the water pump, to the PS unit, to the A/C, to the alternator, etc. etc., and narrow down the source of the noise.

If you don't have a stethoscope, you can use a 3-foot long screwdriver.... put the handle to your ear, and go at it....


-L

By Bill Bettridge (Billb) on Wednesday, October 31, 2001 - 03:34 pm: Edit

Damn Leslie - we keep doing that - LOL

By Leslie N. Bright (Leslie) on Wednesday, October 31, 2001 - 03:44 pm: Edit

We do, don't we??





-L

By Brett Barton (Brett) on Wednesday, October 31, 2001 - 03:45 pm: Edit

If it is the PS pump or water pump, do they have to be replaced or can the bearings be replaced?

By p m on Wednesday, October 31, 2001 - 07:35 pm: Edit

second that, Leslie.

get a very long screwdriver, like 4-5 ft.long.
maybe 6... 7-footer is a bit awkward to handle, and you may bash your brains out (the other ear) if you stumble upon it...

peter

By r22tech on Thursday, November 01, 2001 - 12:54 am: Edit

I don't know what year your truck is, but my 99 series II had the same problem. I tried lubricating each pulley, one at a time, to see when the noise changed to no avail. The dealer replaced the belt and pulley, didn't specify which pulley, and the noise is gone. I suspect it was the idler/tension pulley.

By Brett Barton (Brett) on Thursday, November 01, 2001 - 03:03 pm: Edit

I got the screwdriver and listened to both the idler tensioner pulley and the water pump. The idler pulley sounded a little bit louder/rougher than the water pump. However, I compared them to my new alternator and all three are pretty close. Any ideas to isolate this?