1999 2.4t high frequency noise from engine area.

[Backcabin]

Hi, Can anyone identify what this high pitched noise is on my car? It’s sounds electrical, very high frequency noise . It’s on my 1999 2.4t Volvo v70.
Thank you

https://youtu.be/-x6sqZUR1wY?si=nJE64bCppdIZrYm1

[ITSv40]

VVT pulley?

[Backcabin]

It sounds like it’s more from the back of the engine, turbo area. I’m assuming the vvt gear would be where the timing belt is? The timing belt area is very quiet. Thanks

[SteveSarre]

Hi

If its the very high pitched noise that seems to be loudest between 0:04 and 0:12, then that is when the your mobile microphone is nearest the cam belt and auxiliary belt end of the engine.

Maybe worth reading this thread
https://www.volvoforums.org.uk/showthread.php?t=36416
and using a garden hose to better pinpoint the noise.

I would suspect something to do with the auxiliary belt (alternator, power steering pump bearing, air conditioning pump bearing). You could find out by removing the auxiliary belt and seeing if the noise changes (stops).

And is there a tensioner pulley (and bearing) there as well? I don't remember.


Hope that helps,
Steve

[john.wigley]

I wondered about the a/c compressor bearing too, Steve. It does sound very like the noise that mine made when it was failing on my first Saab 9-3. Trouble with sound is that it can travel and become deceptive as to its origin. I've always had more joy using a stethoscope of some sort - a long screwdriver will do - but obviously care needs to be taken around belts and rotating parts.

Regards, John.

[4x4]

Pop the serpentine belt of and start the car to see if the noise is still there

[Luxobarge]

Originally Posted by john.wigley

I've always had more joy using a stethoscope of some sort .

Me too - I bought a proper mechanic's stethoscope, it was only around a fiver, and money well spent. The probe is long, and in the unfortunate event that it gets caught in something rotating, at least your face and hands are well away from the danger, and it transmits the sound really well and works superbly.

Another vote for running it briefly with the aux belt disconnected. If it's quiet then, you know what area to concentrate on and the stethoscope will tell you what device is whining.

[Backcabin]

Thank you for your suggestions, I will have to have a look over the weekend, I will let you know what happens.

[SteveSarre]

Hi

Pay close attention to the current routing of the belt. There is more than one possible routing, and more than one possible belt length. (I think Volvo changed the routing recommendation and there is a new belt length to go with that).

If your belt is at all old, this would be a good chance to replace with a new one. (In which case you could simply cut the old one off, except that then you would miss the chance to study the removal and refitting process).

Steve

[Baffler]

As SteveSarre says it's loudest when the mic is closer to the auxiliary belt area. To my ears it sounds metallic...a bit like a pulley rubbing against another piece of metal. Pehaps a pulley gone askew, a small stone or piece of grit trapped or a dry pulley bearing? Does the sound increase when you bring up the revs?

All good advice by others...remove the auxiliary belt and test each component for any excessive play and roughness and then run the engine to see if the noise has gone away. If it's still there after running the engine it would do no harm to have a look behind the cambelt cover, whilst the aux belt is removed, just to make sure everything is running nice and true.

Years ago I had a 480 that produced a similar high pitched squeal when the engine reached operating temp. It turned out to be a dry bearing on the cambelt guide pulley but the sound emanated from the middle of the cam cover