986 Forum - The Community for Porsche Boxster & Cayman Owners - View Single Post - Knocking sound coming from left (drive side) rear area

Rui725 · 03-31-2011, 07:27 AM

So I had a chance to slide under my car today, and from what I can access with no lift, I have ruled out the CV joints. both on the left look ok, no grease or tear marks, the inner on the right side had a little grease but it appears to just been engine oil from the engine casing and not the CV joint. The engine casing from that area seems to be very prone to oil seepage, but as long as it's not from the center area then I'm not going to worry too much.

Funny thing is the sound is coming from the left side not the right. But after taking it out for a drive tonight, I've isolated certain situations where the either knocking or light banging sound from the rear left drivers side to:

At the red light, I shift in N (tiptronic) pull the hand brake up. When light turns green, release hand brake, step on foot brake, engage to D, let off brake, let the car roll and accelerate as one would in heavy traffic. At that moment I hear a peculiar sound (most i've heard it in a roll is twice) light knocking, like something is loose or two parts are hitting against each other. It also happens when I release my foot off the brake after engaging D and let the car roll forward before pressing the accelerator. Third incidence that it make the sound is when I'm in reverse and back up very slowly, with my steering wheel turning right.

I thought I have isolated the times the sound was audible so when I got back to my garage, I've re-enacted all the possible scenarios that caused the sound but couldn't hear a thing. So i crawl under the car to check the parts I can see without a lift and everything seems to be fine. Any ideas?

03-31-2011, 07:27 AM	#5
Rui725 Registered User Join Date: Feb 2011 Location: Taipei Posts: 27	So I had a chance to slide under my car today, and from what I can access with no lift, I have ruled out the CV joints. both on the left look ok, no grease or tear marks, the inner on the right side had a little grease but it appears to just been engine oil from the engine casing and not the CV joint. The engine casing from that area seems to be very prone to oil seepage, but as long as it's not from the center area then I'm not going to worry too much. Funny thing is the sound is coming from the left side not the right. But after taking it out for a drive tonight, I've isolated certain situations where the either knocking or light banging sound from the rear left drivers side to: At the red light, I shift in N (tiptronic) pull the hand brake up. When light turns green, release hand brake, step on foot brake, engage to D, let off brake, let the car roll and accelerate as one would in heavy traffic. At that moment I hear a peculiar sound (most i've heard it in a roll is twice) light knocking, like something is loose or two parts are hitting against each other. It also happens when I release my foot off the brake after engaging D and let the car roll forward before pressing the accelerator. Third incidence that it make the sound is when I'm in reverse and back up very slowly, with my steering wheel turning right. I thought I have isolated the times the sound was audible so when I got back to my garage, I've re-enacted all the possible scenarios that caused the sound but couldn't hear a thing. So i crawl under the car to check the parts I can see without a lift and everything seems to be fine. Any ideas? Last edited by Rui725; 03-31-2011 at 07:50 AM.