98 v70xc - serpentine belt (?) whine

eslupin · Post by **eslupin** » 13 Apr 2020, 08:45

Hello, I've developed what seems to be, from other threads here, a whine in the serpentine belt of my v70. I'm about to drive back cross country (Cape Cod, MA > CA) and am trying to (1) decide how urgently it needs to be dealt with and (2) how sure I can be, before taking it somewhere, exactly what's wrong.

re: (1) It's not getting worse especially quickly, and goes away quickly; but I got the sense from other threads here that the belt breaking would be somewhat catastrophic. But others have reported having this kind of whine for a long time. Any one want to weigh in? I'm going to east coast to west coast on 80.

re: (2) The noise: a whine, not ear splitting, but definitely sounds like a belt rubbing
– does not happen immediately on starting the car -
– only happens when i put my foot on the gas -- from about 900 to 2200 rpm; goes away after a few minutes or when engine temp is up to about the 3/4 o'clock position
– does not change pitch much; if anything it gets a little lower up near 2000rpm/when it's starting to fade out

*Without* taking the belt off (I don't have the tool or a way to make one right now), is there anything else I can do to figure out if the problem is the belt itself vs. a tensioner etc.? Does this sound like it's definitely the aux/serp belt rather than timing belt?

(I can post video/audio of whine but I'm not sure it's necessary?)

Getting to a mechanic I trust is challenging at the moment (geographically) and so I'd like to know what I need as far as possible before taking it in....

Thanks and hope you're all doing well. If anyone's out on the Cape and has experience with this (or the serp belt tool !) let me know...

Post by **jreed** » 14 Apr 2020, 05:39

I have a '97 850, so this may not apply to your situation, but I recall thinking I had a belt whine when it turned out to be a noise from the oil thermostat. It is noisy when the car is first started and stops after 2-3 minutes when the oil warms up enough to open up the thermostat fully. My car has been doing this for years and it seems to be working OK except for the noise.

Richard99 · Post by **Richard99** » 14 Apr 2020, 10:46

What is the oil thermostat? Where is it?

eslupin · Post by **eslupin** » 14 Apr 2020, 13:28

@jreed - Thanks - this is helpful, though I can't tell from your description if your 850 was whining immediately on starting or only w/ foot on the gas. Not sure it matters but it seems like it might. Do you remember?

Will look into it in any case.

jreed wrote: ↑14 Apr 2020, 05:39 I have a '97 850, so this may not apply to your situation, but I recall thinking I had a belt whine when it turned out to be a noise from the oil thermostat. It is noisy when the car is first started and stops after 2-3 minutes when the oil warms up enough to open up the thermostat fully. My car has been doing this for years and it seems to be working OK except for the noise.

eslupin · Post by **eslupin** » 14 Apr 2020, 13:31

ps: @richard99: this might help?

Post by **jreed** » 14 Apr 2020, 14:15

On our 850, the noise is loudest when you step on the gas a little bit. It sounds like a ghostly moan. After the car warms up, the sound goes away. I too thought it was due to a pulley or belt, but I temporarily removed the serpentine belt and drove the car and still heard the sound.
Some other descriptions of the problem are available here:
viewtopic.php?t=52275

Post by **scot850** » 14 Apr 2020, 17:02

The oil thermostat is mounted under the crank pulley. The 2 oil cooler pipes run from that to the radiator.

Neil.

eslupin · Post by **eslupin** » 15 Apr 2020, 12:39

thanks, @jreed and Neil -