Odd noise coming from serpentine belt area/front of engine Topic is solved

sventastic · Post by **sventastic** » 12 Apr 2018, 15:41

So this noise started up yesterday sometime while driving. I pulled over and had a look and couldn't see anything visibly wrong and have driven it 30km more or so. It seems to be coming from the serpentine belt/PS pump/AC compressor area but I can't pinpoint it, and I'm wondering if anyone has heard something similar. It's only audible while stopped, once I start driving I think road noise drowns it out. Tough to tell, but I don't think it's RPM-dependent

Background on the car: 1996 850R, 245,000km, toooons of maintenance in the past 15,000km. Serpentine belt/timing belt/WP, etc, etc all replaced at 231k. Ignition system is all less than 20k, PCV has 16k, oil pan seals, oil cooler line seals and oil cooler thermostat seals done 4k ago

If anyone has ideas, I'm all ears! My first impression would be the power steering pump or one of the serpentine belt pulleys is on its way out.

Post by **scot850** » 12 Apr 2018, 16:08

I would suggest (based on not being able to hear it clearly) that is may be one of the pulleys bearings in the serpentine belt area.

As abscate and others suggest usually, try a piece of hose held to your ear as a probe, but be VERY careful around the moving pulleys and belt. Also, if you have a Harbor Freight or likes around you may be able to pick up a cheap mechanics stethoscope and try using that, but same safety concerns.

I find identifying the bearing on that belt path difficult to hear as so much noise travels through the aluminum housing supporting the majority of the components. Pull the serp. belt and see if the issue goes away. Perhaps with the belt off, spinning each pulley bearing may be more fruitful.

Good Luck!

Neil.

Post by **rguzz** » 12 Apr 2018, 16:59

Hopefully noise will go away when serpentine belt is removed. As Neil suggested, go from there, looking for something that turns which has play, or is noisy. Next step might be to remove TB cover and inspect everything that moves and is belt related there, though sounds like alternator area is source of noise. Looks clean under that hood!

sventastic · Post by **sventastic** » 12 Apr 2018, 17:53

scot850 wrote: ↑12 Apr 2018, 16:08 I would suggest (based on not being able to hear it clearly) that is may be one of the pulleys bearings in the serpentine belt area.

As abscate and others suggest usually, try a piece of hose held to your ear as a probe, but be VERY careful around the moving pulleys and belt. Also, if you have a Harbor Freight or likes around you may be able to pick up a cheap mechanics stethoscope and try using that, but same safety concerns.

I find identifying the bearing on that belt path difficult to hear as so much noise travels through the aluminum housing supporting the majority of the components. Pull the serp. belt and see if the issue goes away. Perhaps with the belt off, spinning each pulley bearing may be more fruitful.

Good Luck!

Neil.

rguzz wrote: ↑12 Apr 2018, 16:59 Hopefully noise will go away when serpentine belt is removed. As Neil suggested, go from there, looking for something that turns which has play, or is noisy. Next step might be to remove TB cover and inspect everything that moves and is belt related there, though sounds like alternator area is source of noise. Looks clean under that hood!

Thanks for the input guys! Much appreciated.

The plot has actually thickened a bit, but this may help narrow things down, since it eliminates any rotating parts and belts. The noise continues to be present when the engine is off, and the key is in position 2.

New video with engine off

Also if you guys want to nerd out on a Volvo story here's my thread from VS
http://volvospeed.com/vs_forum/topic/17 ... r-project/

Post by **cn90** » 12 Apr 2018, 18:57

- Probably dry bearing(s) at 150K miles...

- As others have said, remove the serp. belt.

- Then spin each component: idler and tensioner pulleys. If they free-wheel and keep spinning after you release your fingers, they are bad. Shake them sideay to see if there is any play. Then spin AC Pulley. Then spin alternator pulley.

sventastic · Post by **sventastic** » 12 Apr 2018, 19:27

cn90 wrote: ↑12 Apr 2018, 18:57 - Probably dry bearing(s) at 150K miles...

- As others have said, remove the serp. belt.

- Then spin each component: idler and tensioner pulleys. If they free-wheel and keep spinning after you release your fingers, they are bad. Shake them sideay to see if there is any play. Then spin AC Pulley. Then spin alternator pulley.

How could it be a bearing? In the latest video I posted above, the serpentine belt is not engaged and there's nothing spinning, the engine is off yet the noise is still present.

Not sure if it's worth noting that my fuel pump whines somewhat loudly

Post by **ZionXIX** » 12 Apr 2018, 19:37

sventastic wrote: ↑12 Apr 2018, 19:27
cn90 wrote: ↑12 Apr 2018, 18:57 - Probably dry bearing(s) at 150K miles...

- As others have said, remove the serp. belt.

- Then spin each component: idler and tensioner pulleys. If they free-wheel and keep spinning after you release your fingers, they are bad. Shake them sideay to see if there is any play. Then spin AC Pulley. Then spin alternator pulley.
How could it be a bearing? In the latest video I posted above, the serpentine belt is not engaged and there's nothing spinning, the engine is off yet the noise is still present

Not sure if it's worth noting that my fuel pump whines somewhat loudly

I recall a guy several weeks ago had an air pump that was running and making noise with just the battery on. It lives somewhere near the throttle body and transmission?

Post by **ZionXIX** » 12 Apr 2018, 19:44

Found the thread: viewtopic.php?f=1&t=84322&p=462504&hilit=noise#p462504

sventastic · Post by **sventastic** » 12 Apr 2018, 20:24

ZionXIX wrote: ↑12 Apr 2018, 19:44 Found the thread: viewtopic.php?f=1&t=84322&p=462504&hilit=noise#p462504

Thanks for the link! It appears the noise was coming from the headlight wiper motor, just like in that thread. I unplugged it and turned the key to position 2 and the noise did not come back. Started the car, still no noise. Plugged the motor back in and the noise did not start up again, so we'll see how long that lasts. Both headlight wipers still work properly when cleaning the windshield. I wouldn't call this fully solved quite yet but I think there's a good chance that's all it was.

Post by **erikv11** » 12 Apr 2018, 21:07

LOL at "probably a bearing" when the noise persists with the engine off. Sometimes actually reading the thread is just too much work ...

If the wiper motor gets jammed you can reset it by unplugging and plugging back in, sounds like you found it and fixed it. Well done.