Bruce In Philly

2009 C2S Coupe, 46K miles

This has been bugging me for about a year. I just have not had the time to look into it.

I get a clunk from my rear (the car) when I go over a sharp bump like a parking trundle or garage speed bump. I don't believe this is a classic control arm issue as it takes a sharp bump to really pop the back end up. (I replaced more than a few Porsche control arms so I think I know the sound.)

It is a deep thunk (not metallic) that sounds like it is coming from atop the engine, maybe the right/passenger side. I noted it "sounds like its coming from" but I am not really sure. My active imagination tells me the engine is lifting and dropping like a bad mount or something.

It is really bugging me lately as I am parking in a garage with those really hard, short, rubber speed bumps they bolt into concrete. They are narrow and high so my car lurches up and then I get the clunk.

Anything I can look at without a lift?

Peace
Bruce in Philly

PhilD

Could be worn motor mounts. Is one of the exhaust tips lower than the other? If so, I would suspect motor mounts.

Macster

Based on your post I think PhilD has it. Motor mounts. I mean you even alluded to these in your post.

Confide in a trusted Porsche tech then he'll get the car in the air and check it out.

About all you can do in the meantime is be sure you can reproduce the behavior on demand at a location near the dealer if you have to demo this to the tech in a road test.

It occurred to me you could have someone drive your car and generate this behavior while you watch/film the car from outside the car and then see if you can spot say the exhaust tips/outlets moving around unnaturally.

LexVan

Sometimes when it's the motor mounts, a person following behind you can even see the exhaust tips move up and down from acceleration and deacceleration.

Bruce In Philly

Good stuff, thanx. I will do all of the above.

A friend told me to check to see if they are leaking and that can be done from below. Tomorrow night I will be at a friend's home who has a grease pit...... stay tuned.

Peace
Bruce in Philly

LC MotorSports

Also check the shock top mounting plate as well.

PhilD

You may see a leak, but you may not if all the fluid is already drained out. Just have someone stand behind the vehicle and if the tips move when you give it some revs.

LexVan

Or use your smartphone on video setting.

Linnm

Loose muffer or exhaust clamp

red996

+1

Bruce In Philly

How do I do this? From above? below? I will have the car over a grease pit but won't have my floor jack.

By the way, I found we can see the two rear engine mounts from above. They are the silver discs to the far left and right of the airbox. I put my hand in and around the thing as best I could and could not find evidence of leakage... at least I felt nothing when I reached under the mount.

Peace
Bruce in Philly

Wolfk

Top rear shock mounts are under the carpeted panel behind the rear seats.

Spiffyjiff

do you have stock suspension? i have upgraded to bilstein damps but my passenger rear does this - the lock/coil perch nut gets caught on the rear dog bone. i can see the scars on both to prove it. makes a clunking noise sometimes if the speed of the hit and pavement bump are drastic enough.

Rotmilky

I get a metallic clunk from the rear when I go over sharp bumps. In my case, it has something to do with the headliner mounting support just above the rear window. If I reach back and hit the headliner just in front of the rear window with my hand, I can make it 'clunk'. Yours sounds farther back and lower...but you never know.

Bruce In Philly

Update: I just ordered some sway bar drop links. I went under the car over a friend's grease pit and whacked on everything with a rubber mallet, and wedged a bar between the parts... and..... I still have no clue. Oh, I pulled up the carpet and checked the three bolts on the top of the strut and they were tight. Nothing was leaking from the rear motor mounts.

The links have a green washer(?) in them one looked cracked. Not sure this is relevant, but what the heck, buy some new ones. Pelican had Porsche and Lemfoerder options but the prices were all wacky with left and right being different and Lemfoerder being more expensive than Porsche for one of them. So I called Pelican and agreed it was wacky but the prices were correct. He noted the Lemfoerder is a supplier to Porsche for the links and I got free shipping with the Lemfoerder so.... I got the Lemfoerder for about $95 for a pair.

I will report next week if this cured my clunk or not.

Peace
Bruce in Philly