Greetings. I have a 1999 xc70 with 152K miles. I am getting a very loud knock-knock--knock-knocking that is wheel-speed sensitive. It appears to be much louder under load.

I replaced the center drive shaft with a remanufactured unit from Colorado Driveshaft fourteen months / 9,000 miles ago. My inital guess without getting under the car is that the sound is coming from directly in the middle of the drive shaft at the middle u-joint.

Has anyone heard of an angle gear making such a sound? The Colorado Driveshaft folks are thinking that might be the cause.

Any guesses as to what is making this sound?

 

Update - the sound is definately coming from the rear of the car, not the bevel gear area. Plus, there is some lateral (and loud) play in the rear CV of the center drive shaft.

 

I would remove the driveshaft and see if the noise goes away. I would also check the joints in the driveshaft.

 

hi check play in the bevel gear sleeve by turning the propshaft you should have no play when turning back and forth or either lift all four wheels off the ground and drive the car to see if the back wheels are turning as this a very common fault as the bevel sleeve suffers from worn splines