Hi all,

On my 740 I've got a high pitched intermittent squeal when turning the wheels every so slightly. When the steering wheel is straight there is no squeal. If i ever so slightly to the left, a matter of degrees, the high pitched squeal starts. If i turn it more, it stops again. So the squeal only appears when i turn the wheel from straight to about 10 degrees to the left. I ruled out that it isn't a transmission issue nor an engine issue. The squeal starts after i'm going about 40 kmh or more, and it isn't an engine revolution problem - it happens no matter what the revs are, just as long as the car is going 40kmh or faster. When braking, the squeal goes away. The brake pads have plenty of life on them, and so do the rotors. There is not debris anywhere on the calipers. It's not really loud, but it's very high pitched and SUPER ANNOYING, as i drive with my drivers window open. It's driving me crazy!

I was thinking it might be the wheel bearing, but i don't want to spend $100+ on a wheel bearing and then find out that its not the issue, so i'd like to investigate the definite cause of this first.

 

squeals when you turn your steering are often the power steering pump drive belt.

 

I am 99.9% certain its not the power steering fan belt. I've had all belts replaced 5000km ago and the actual power steering pump is about 40,000km old. Also, the squeal is not related to engine speed, but to road speed. I don't get the squeal when the car is stationary, only when i am driving above 40kph. So i highly doubt its anything to do with the power steering unit and/or belts.

 

Just because the belts are new doesn't mean they are installed and tensioned properly. I would double-check on the tensioning just to be sure as from your description it sounds like a belt issue. Check the alignment of the pulleys as well. Many times with the age of these cars the rubber mounts of the accessories get old and cause the pulleys to no longer be in alignment.

 

did you try rotating tires front to back to see if any difference?

 

I'll try that today. Quite a simple solution, so ill give it a go.

 

check the tires for wear too. How does it drive? does it pull or feel loose? When was the last time the alignment was checked? I'd think if you were getting some belt noise, you'd hear it backing out of a parking spot or making a K turn. A tire/wheel alignment issue can produce some scrubbing squeals but I'd think that'd only happen while while driving at speed.

 

I just had the tyres replaced 300km ago 2 weeks back. I put on very good quality Good years and they were aligned. I'm starting to think that it might be a wheel bearing issue or something isn't lubricated right. When driving, you can clearly hear it is coming from the wheel not the engine, so i highly doubt its the belts. They are aligned and tightened properly.

 

Wear indicators on the brake pads?

 

6mm on the brake pads left all around.

 

stilll could be a brake issue, if one of the calipers is frozen and dragging. I'd probably look around for any rotor cuts (inside and out) and do some brake tests to make sure there's no pulling etc and check the ebrake as well. As to the wheel bearing - could be that or an axle although the more common sounds are rumbling for a bearing (which changes sound turning left vs right due to the change in load on the inside / outside wheels) and axles will commonly click vs whine. Try a road test turning left/right (say 30-40 mph sweeper turns) to stress the bearings and see if the sound changes while accellerating or decellerating (stress/destress on the axle)