I recently picked up a 2005 S-Type, and there is a whine that is tied to the accelerator. The pitch of the whine increases with vehicle speed. At low speeds, it's kind of a howl, and on the highway it's a high-pitched whine.

The noise only happens when I press on the gas pedal. When I'm in the driver's seat, it seems like it's coming from the rear right-hand side. I assumed it's either a busted wheel bearing or something's busted in the driveshaft/rear differential.

Any advice on how to narrow this down? If it's not a wheel bearing I'd rather not spend the $100 and 2 hrs to replace them and have to fix something in the tranny a week later.

Engine codes are the 1, 3, 5 cylinder misfires (I think from oil in the spark plug holes) and the 1532 IMT bad O-rings in the gasket. I haven't fixed that yet.

Thanks!

 

Edit: the whine doesn't occur when I first start driving. It takes a few minutes to warm up, then the vehicle starts to whine when I press the gas pedal.

 

Drain the differential oil into a clean pan. Look for any debris or silvery sheen. You could even slowly pour the oil through some kind of filter paper into a second pan. I'm thinking something like a big coffee filter, and maybe rig up some sort of support like a can with holes punched in the bottom. Then you'd really be able to spot any debris.

You could try some sort of additive (like Lucas Oil) in the differential. If the noise changes, for better or worse, at least you'd know you're in the right place.

If I had to wager a guess, I'd lean towards the differential. Worn gears tend to howl or whine (edit) and are load/RPM dependent. Bad wheel bearings cause more of a deep irregular rumble (edit) and follow vehicle speed, in my limited experience at least.

 

Your misfires may be an air leak or some problem common to one bank. I'd fix the problem first in case it makes the howl/whine go away - the car cannot run properly till the known fault's fixed.

 

Excellent advice there. Who knows, maybe you're getting some weird misleading noise from the exhaust.

 

One way to eliminate the wheel bearing/tyre noise is to have the rear wheels off the ground and gradually accelerate to determine if the noise is still present or not. If the noise is still present, the location can be determined much easier with the vehicle lifted.

When draining either the differential or gearbox, ALWAYS remove the fill plug first prior to removing the drain plug.

 

It is a serious breach of protocol to casually mention a juicy tidbit like this, obviously with a hard-learned lesson behind it, and NOT tell the story.

Bonus points if the story involves spraying your boss with gear oil...

 

Not something I have personally experienced, but have had friends needing to be towed to a shop after draining the gearbox and then not being able to remove the fill plug when it was time to refill.

 

Thanks everyone for the responses! (Especially about the fill / drain plugs...)

I ordered the O-rings for the IMT gaskets and I'll get to fixing that up as soon as they arrive. I'm the meantime I'll jack it up and do some pokin'round the transmission and stuff, see if I can pinpoint the noise. I played around with the car in neutral for a bit and there was no noise as far as I can tell, so I guess it's time to do some lifting.

I'll post any results if I can figure anything out. Thanks again for the help!