Help with strange noise Volvo S80 2.5T

garortca · Post by **garortca** » 14 Apr 2012, 08:11

Two days ago begans a strange sound. It appears only when engine is hot. It is like a whistling and it comes from the rolling part where the belts are placed and from the upper part of the engine. When i put engine off I can hear someting like a coffee grinder until it stopps completely. Please help me if anybody can know what is happening.

Post by **dcarlson12** » 14 Apr 2012, 14:33

sounds like a bearing failing in one of the items powered by the serpentine belt??

garortca · Post by **garortca** » 15 Apr 2012, 04:23

Thank you dcarlson12 but if it is a bearing why beguns the sound only when engine is hot after 5-7 minutes ? I think it is too much time if a bearing is failing. Otherwise it sounds like a whistle, high pressure air or a valve that is failing anywhere at the upper part of the engine.
When I put off the engine I can hear clearly that anything that is rotating with a really high speed stopps (coffee grinder sound).

Post by **jimmy57** » 15 Apr 2012, 10:32

pull out the dipstick and see if it stops.
If so, there is a problem with crankcase vent system. There is a check valve on the turbo with a hose leading to it. The check valve may be stuck. The intake manifold gasket has a check valve adjacent to each intake port. One or more of those could be clogged or stuck open.

Dirtbag454 · Post by **Dirtbag454** » 19 May 2012, 23:48

Did you ever find the cause? I listened to the audio on the vid, and I'd stake my reputation as a Bullsh**tter that it is a serpentine idler. You also might want to check the alternator. They make odd noises like that when the bearings are leaving. One quick test I have used on domestic engines is to unplug the alternator. When you de-energize it, the load on the bearings reduces dramatically, and if that is the problem, there will be a noticeable change in the sound. I qualify this last bit of advice because you never know how a Volvo will react to unusual electrical inputs (or lack of). I had an alternator go away on an 850, and take the instrument cluster with it. Get a mechanics stethoscope and listen to various locations on the engine. The noise will reveal it's source. Poke that alternator.