I just bought a 2008 S40 from an auction (no history).
It has 177k miles.
Brand new tires.


When turning left (even very slight turning) it makes a thumping noise in the front end. The noise speeds up when speed increases.


Noise goes away when I straighten up and occasionally hear it slightly when turning right, but ALWAYS when turning left.


I took front tires and put them on back > Didn't change any.


Tried to shake the tires when jacked up but they seem very solid (wheel bearings good).


Is this a CV axel problem? If so, which side is likely bad?


Thanks in advance, Keith

 

Also, when I put it into neutral, the sound continues.


It definitely speeds up and slows down with tire speed and NOT engine RPM.


Again, any/all help is appreciated.


Thanks,

 

CV joint is the most likely culprit. Should show itself in a torn rubber boot and grease slung out of it. Drive with only the drivers window down, then only the passenger side down if it doesn't immediately appear to be coming from the drivers side.

 

Usually CV's will "click" rather than "thump" , and internet diagnosis is tough ... but I suspect a bad hub bearing. Could very well be the CV though, so check the boot as stated above.

 

Not know how you checked the bearings, bushes, etc, it's hard to pinpoint.
I agree, a worn CV will usually click away when turning.
Raise the hood and push down on the front corners. Do the strut mounts move at all? One I just did would clunk away, it was a TRE and both strut mounts. Maybe an hour or so to do both jobs.

Martin

 

good advise here - the five most common sources of suspension noises are strut mounts and sway bar end links - which usually show going over speed bumps, rough roads as a thump or knock. brake rotor/pads, CV joints and wheel bearings show by changing tone/volume with road speed. As noted CV joints generally click or whine and change with steering. Wheel bearings "moan" (my 850T just got a new wheel bearing this week to quiet the "wub wub wub" it was making). Bearings may also change tone with turning - as you turn one way, it puts more load on the outside wheel which increases the noise, but it can be very subtle. If you hear more noise turning right, check the left hub. Turning left, check the right... You can check front bearings by jacking the front end and rotating the wheels by hand - you can try putting your hand on the spring to feel for any vibrations from the grinding or use a listening tube. As noted most CV joints go bad due to losing grease from a torn boot. Last is the brakes - if the noise/vibrations changes when you lightly apply the brakes, then inspect pads/rotors.