Help with a strange raspy whining noise
 

Hi all

I have a Volvo XC90 Inscription 2015 with about 93,000 miles.

It has a full service history and I have had no issues of substance to date, great car.

I did a 500 mile round trip on Thursday and then on Friday when I drove the car I could hear a whining raspy noise when a I was traveling at low speeds 30mph.

I took the car on the motorway and no issues, the noise went away or at least I couldn't hear it. When I dropped down to 30mp again though the noise was present again.

The noise is present at those speeds and when I am coasting not pressing the accelerator. when I parked up I put the car in neutral and slightly put my foot on the accelerator and it was present again, the more I pressed the louder it gets to a point and then it can no longer be heard. Seems linked to accelerator but strange it is present at low speeds when I am coasting.

It remains when coasting downhill, if I move the steering wheel and like I say is present when parked in neutral with my foot slightly on the accelerator so don't think its bearings.

Does anyone have any idea on what this could be ?

I don't think the car is underpowered or at least its difficult to tell but I do feel when I take my foot of the accelerator there is a little delay in the the revs coming down, albeit that could be me overthinking it a little.

The noise is similar to when kids used to put cardboard in their tyres on bicycles, although its not overly loud, only slight.

Any help much appreciated

Hi
There are still plenty of bearings moving around when you are stationary. Such as those in your alternator or your water pump etc.
Last time I had a similar noise it was the alternator. I would lift the bonnet and expose the auxiliary belt and listen down there, you may find its coming from something down there.

Thanks for that Alex I will take a look.

I am just hoping its not the turbo.

I had a strange whining noise coming from my T4 years ago, stopped when i got divorced.

Have you checked the tyres to see if there is some cardboard stuck in the spokes? :tongwink:

If the noise is there when you are parked up and in neutral then it will be in the engine bay and the drive transmission is in the clear. Have a look under the bonnet.

If it's there with the engine ticking over while parked there's always the old skool trick of taking a length of wood and positioning one end on a bearing or suspect part then putting your ear to the other end to listen, posh mechanics use a proper stethoscope device :)

I have used a home made stethoscope in the past to locate such a noise.
A couple of feet of plastic tubing with a small plastic funnel jammed in one end. Place the funnel to an ear and the other end of the tube against whatever you wish to check. It’s amazing how much sound can be heard. Tappet noise when placed against the camshaft cover. Bearing noise when placed against a water pump or alternator. etc.

Is it worse when the engine is cold just after starting? If its bad when decelerating or coasting then I would check the alternator pulley as it will have a clutch that allows it to free wheel one way but drive the other, if this has failed and there is no freewheeling the belt slips and causes all sorts of weird noises. It took me about a week to find it on my car, you have to remove the auxiliary belt and then stick a screwdriver or preferably a piece of wood in the alternator to stop it spinning and check the pulley drives one way but freewheels the other a bit like a bicycle.