Help to isolate noise - 986 Forum - The Community for Porsche Boxster & Cayman Owners

hookoo3 · 07-09-2011, 03:38 PM

I need help to identify a noise which is getting louder. At first I thought the noise might be tire wear however my fronts are new and the rears were replaced about 5000 km ago. One tire dealer thought it may be cupping noise however the noise is now getting louder with a more metal grinding type of noise. I've had the car up on jack stands and do not hear the noise when engaged in 1st. I do not think it is the bearings as I don't hear any noise when on the jack stands or when driving and holding out my head out the window. I've also now replaced the front motor mount which was worn out and the metal grinding low pitched noise is still there. The noise can be heard in all gears and with the clutch pushed in or out. It does appear to be on a constant rotational basis. The noise seems to come more from the center of the car and is now a metal type of grinding noise on every rotation. Any suggestions on what next to check out is appreciated. Thanks.

2001 Boxster S 6sp 93000km

Jager · 07-09-2011, 07:11 PM

Wheel bearings do wear-out on these cars... Both front and back.

hookoo3 · 07-09-2011, 07:42 PM

Is there a definitive test to figure out which wheel bearings may be going out? Spinning the wheels and listening to each one has not given me any idea if something is wrong. Another thing I have noticed is that it makes the noise only in forward gears, there was no rubbing grinding noise in reverse. And the noise happens on every rotation that is going on. The clutch and shifting seem normal to me. The brake pads are in good condition and on hard stops the car stops fast and smooth with no vibration or pulling. The rear CV boots and bearings were replaced less than 2000km ago. There are no oil leaks on the car. Is there an easy diagnosis for the transmission or differential? Ideas are welcome. Thanks

thstone · 07-09-2011, 10:52 PM

I'd suggest checking the CV joints (check both inner and outer joints).

There is no differential (per se) on a Boxster since the car has a transaxle.

hookoo3 · 07-10-2011, 11:35 AM

thstone, I think you may right. I checked my receipts and I see that all 4 cv boots were replaced and none of the cv joints. The outer boots were quite torn at the time so I now suspect the cv joints are done. Looks like I'll be replacing the complete axle shaft assembly now.

Has anyone actually used the cheap First Equipment Quality parts from China that are almost a tenth of the price of OEM? I know most will not recommend cheap knock-offs but has anyone had any results or reviews using them?

Dale_K · 07-11-2011, 05:04 AM

Auto parts stores sell a special grease for repacking CV joints. It would probably be worth the trouble to peel back one of the boots and see what it looks like inside. If it's really dry you could clean it up and re-grease it. Kind of a low probability repair effort but since it's so cheap (only cost is the grease) it's worth a shot.

jcb986 · 07-12-2011, 05:23 AM

You could check with a few of the Porsche dismantlers for some used one's.

hookoo3 · 07-21-2011, 04:06 PM

Hi, I've now replaced both axle shaft assemblies with new original Porsche parts. The grinding noise is still there. I can't really tell where the noise is coming from and it is a rubbing/grinding noise on every rotation. How can I identify if it is a front wheel bearing? What are other possible causes for the grinding noise? Thanks.

jhandy · 07-22-2011, 03:51 AM

does it get louder if you turn left or right?

get to about 50, put in the clutch, and coast, turn the wheel if the front bearings are really bad, it will make the grinding noise louder when you put pressure on the bearing. IE: more noise when turning left=right bearing out.

kabel · 07-22-2011, 05:13 AM

I am unclear, you only hear the noise when you are in motion, and not stopped correct? is the noise wheel-speed dependent or engine-speed dependent?

Even after inspecting all the other various suspension and mechanical components that might be the cause the noise, It could still be a tire(s). I've been through that only to finally put a new set of tires one and that solved the issue.