: Main Acc Drivebelt - Whine & Grind Noises



BostonETC97
03-18-05, 12:05 AM
As I was sitting in the idling eldo tonight, I started to hear an occasional groan from under the hood. Ten minutes later, the whine from under there got louder, but would dissapear with a blip of the throttle. I pulled the belt tensioner back while it was making noise, and all went silent. (The accessory belt sure makes a lot of noise - the engine was practially silent at idle with it off!) I found whatever pulley was making noise would go silent above 1200RPM, and start 'whining' again at idle. But I can't figure out what pulley (or accessory) went bad...

Are there any particular pullies that are notorius for eating their bearings? Anybody know a good way to test each pulley to find the culprit? The A/C compressor was off tonight, as it was 30 outside. I'd love to fix this one myself, but I got a feeling the dealership will be getting a call on this one tomorrow...

Otherwise, 78k miles, on nothing but oilchanges and a minor tuneup!

As always, thanks for the help!

-Scott

BeelzeBob
03-18-05, 12:08 AM
Check the idler pulley bearings. With miles and years the bearing can dry out and start to get noisy. Same for the pulley on the belt tensioner. Those are the only two pulleys with their own bearings so they are the first suspects. Possibly the AC compressor hub bearing also. Even with the AC off the pulley on the compressor is free wheeling on the hub bearing and could be noisy.

Take a 3 foot piece of hose of some sort and put one end in your ear. Move the other end around to the various pulleys while idling to hear which one is making the noise. use the hose like a stethascope.....

eldorado1
03-18-05, 01:01 AM
Also, just because it's not making a noise when you turn it, doesn't mean it doesn't make noise when it's under belt tension. My tensioner pulley barely makes a noise when I spin it without the belt..... but put that belt on, and it'll start screaming. I had to take it apart, and regrease the bearings, and it took out 75% of the noise, but it's still there, eating at my brain. http://cadillacforums.com/forums/images/smilies/banghead3.gif

BostonETC97
03-18-05, 01:38 AM
Is the pulley and bearing replacement an easy project? Basic hand tools and all done through the top of the motor? It's warm tomorrow, and the AC Delco wholesale parts counter is just down the road... I'm in the mood to do some repair!

Getting the belt off looks to be no problem. Would it be overkill to swap out all the pullies (just idlers & tensioner), since they're all probably nearing the end of their "silent performance" life and are getting noisy?

Pjs
03-18-05, 07:44 AM
I just replaced the belt tensioner on mine last week, for the very same reason. At idle it would make some horrendous noise, but with a little blip of the throttle or put in neutral or park would quit. Replacing was real simple, takes about 10 minutes. Remove the battery, take the belt off the top pulley (power steering), remove the one bolt that holds the tensioner on, then reverse the process....very very simple.
Autozone stocks that piece for $56

BostonETC97
03-18-05, 01:09 PM
Now I'm just at a loss. After driving all morning, the car is quiet. I've been trying to replicate the noise with no luck. The a/c compressor is running today, and other than the "click-clack" of it energizing and disengaging, there's no abnormal sounds.

Maybe I ran through some puddles last night? Maybe playing with the tensioner "reseated" the loosening bearings?

One thing I've always loved about GM cars, they have a very strange way of fixing themselves overnight. No other line of cars that I've owned could do it!

Regardless, I know I'm due to replace the serp belt, since it's original to the car. I think at nearly 80k miles, it really doesn't owe me any more service. It still looks to be in great shape, no splits, the ribs still look flawless. I'm sure it has stretched out of spec a bit, and is probably getting tired. I'll have it replaced and throw the old one in the trunk for a temporary spare should I ever need one. Cheap insurance!

While I'm doing belts, should I replace the water pump belt? It too looks great, still has original markings on it, but has seen 80k of service too. Replacement a good idea now?

...Funny how at nearly 100k miles, the cars today just need "plugs & a belt." I remember when every 30k valves had to be set, timing adjusted, etc etc. Now I see why so many small shops no longer exist.... maintenance and tuneups are really a thing of the past!

-Scott