2006 Xc90 Whining noise, knocking noise while driving

ibaker19 · Post by **ibaker19** » 21 Oct 2015, 10:32

I purchased my used Xc90 last spring. About a month later after my warranty was up i started to notice my car was progressively getting louder. Now 7 months later the whining noise has become louder then ever. The noise starts immediately when i turn on the car and seems to match the cars rpm as i accelerate. The noise gets louder as the rpms increase. I took the car to a certified european car mechanic, He believes the noise is coming from the alternator, but wouldn't i have had problems with the car starting by now if that was the case? i noticed that when i turn the wheel when im idling that the noise gets quieter for a brief second but then immediately goes back to sounding terrible. Could it be the power steering pump needing to be replaced? What would cause this?

My second issue with this car is that when i'm driving at low speed there is a noticeable knocking noise that almost sounds similar to a baseball card in a bikes wheel. The faster i go the louder and more frequent the knocking. The knocking only occurs when i'm coasting or barely touching the gas. The knocking stops whenever i hit the brakes or the gas. The noise seems to be coming from the front of the vehicle

Im a college student so i cant really afford to pay for parts that dont fix the issue.

Ou2mame · Post by **Ou2mame** » 21 Oct 2015, 13:38

Your accessory problem could be any of the accessories on the serp belt. You should remove the belt and turn the accessories by hand and see if any of them are grinding or loose. It could be the belt tensioner as well.

As for the 2nd issue, it could be a wheel bearing. Does the sound disappear while turning either direction? Are your cv boots in good shape?

ibaker19 · Post by **ibaker19** » 27 Oct 2015, 18:39

So im not the most mechanically gifted. Is there anyway to check the serp belt without taking it off?

for the second issue, the noise will stop knocking if i turn the wheel a little bit. but when im turning hard the knocking returns and disappears as i turn the wheel back to straight.

Ou2mame · Post by **Ou2mame** » 28 Oct 2015, 01:10

You've got to take the serp belt off to see if there's any problems with the accessories, or it could be the tensioner too. If you don't want to do it, you're gonna have to bring it to a mechanic. You can't do much with the belt on, but chances are you're gonna have to take it off and replace something. If you can't do that you might as well just have someone else do it and not waste the time trying to diagnose it. Honestly, it's not hard though. There's numerous YouTube videos that illustrate the procedure. Taking the passenger wheel off and opening the access door helps a lot if you want to look and see if anything is wobbling while it's moving.

Your 2nd issue sounds like a wheel bearing or cv joint to me. Depends on the symptoms. With a wheel bearing, the noise will stop if you turn one direction and get worse if you turn the other, at speed. A cv will generally start clicking and popping at low speed while turning, like when you're parking.

ibaker19 · Post by **ibaker19** » 28 Oct 2015, 15:59

Alright well i appreciate the help. Im just gonna take it to a mechanic within the next couple weeks and see if they can resolve the issues. Ill keep you updated

Ou2mame · Post by **Ou2mame** » 28 Oct 2015, 17:15

I had a problem with mine where the belt was chirping and the power steering was stuttering.. I replaced the tensioner and serp belt and that was the fix. Took about an hour. I've been working on cars a long time but I'm no professional mechanic or anything, and with basic tools and a serp belt tool I got at Harbor freight it was pretty easy.