97 850r Weird sound at startup..belt?

koffinb · Post by **koffinb** » 30 Sep 2014, 20:57

I tried my best to get the sound in the video but I am not sure if it can be heard. It is a high pitched, whining sound coming from the engine area when the motor is revved after sitting for a day or so. The noise does go away after a couple minutes of driving, but I am leaning towards one of the serpentine belt components possibly?

The noise can be heard better at the ed of the video after I shut the door.

Post by **phils94850** » 01 Oct 2014, 05:54

I listened to your video and its very difficult to hear the noise your talking about. I would shoot another vid with someone under the hood with the camera while someone is pressing the accelerator or you can just move the throttle from under the hood with your hand. My guess... is going to be a serp belt.

There is a old mechanic trick but you must BE CAREFUL... take a bar of soap while the engine is running and let the serp belt ( pulleys side ) get soap on it and then see if the noise stops if it does then its a sign its the belt...

Post by **rspi** » 01 Oct 2014, 07:05

When I had a cold start noise, it was the timing belt idler just about locked up, about to toss the timing belt. You can pull the serpentine belt (or lock it loose) before you start the motor cold. If you still hear the noise, it's a timing belt part, if you hear no noise, shut the car off, put the belt back on and start it again. If you hear it then, it is likely a serpentine belt path part.

koffinb · Post by **koffinb** » 01 Oct 2014, 11:59

Here is a better video, it is still kind of hard to hear, but I hope you guys can pick it up. Around 45-55 seconds it becomes kind of clear to hear. I can't tell if it's a belt noise or not. Timing belt and tensioner were replaced 20k miles ago

Post by **phils94850** » 01 Oct 2014, 20:44

I would take the serpentine belt off and then start the car and see if the noise goes away, if so then you know its a component such as tensioner, power steering pump, a/c compressor etc. I would try spinning each component by hand until you find the faulty one.
if it does not go away then you know the problem is in the timing components..

koffinb · Post by **koffinb** » 01 Oct 2014, 20:46

Sounds like it's coming from the rear part of the engine. A vacuum leak somewhere back there maybe?

Post by **abscate** » 02 Oct 2014, 13:14

Its sounds to me like an alternator bearing, but Ill put 50% confidence level on that.

I would pull the serpentine belt as recommended above. You might be able to diagnose the power steering pump by having someone turn the wheel while listening to see if the sound changes

You might also be able to do the same with the alternator by loading the electrical system with high beam headlights and listening for changes in the noise.