Clunking sound when in reverse
 

Hello everybody.
Just bought a 2002 Boxster man 5 speed. When I'm backing up there is 2-3 clunck sound, I put it forward and the samething happen. Once on the road there is no cluncking sound. I just remove the rear stabilizing bar to rule out this, but nothing change. Anyone had the same problem? The sound seems to come from the rear of the car. Help would be very appreciated.

This is a video I recorded with the clunking sound.

https://1drv.ms/v/s!AmSrLd3csx6CggFAnTHv-EqsHnrN?e=qhhYSP

Motor or transmission mounds?

Is it difficult to check?

For the transmission mounts look for hydraulic fluid on the ground directly under the respective mount, of which there are two. If it isn't leaking... another method might exist suggested by someone more knowledgeable than I.

Visual inspection of the motor mount.

Good luck.

I would jack up the rear of the car and try to reproduce the sound by moving the tires. Could be CV joints.

Thank you all for the replies.
There is no oil leaking from the transmission mounts. For what I can see the engine mount looks ok.
Could it be because one of the rear tire has less life in it than the other one.

When going in circle in reverse or forward it is worse.

I will try to raise the rear of the car to see what happen.

If your car has the original motor mount then it is shot.
The rubber center portion wears out and degrades with age.
You can't see it with a visual inspection it has to be removed to see the problem.

Or you could have an issue with the rear axles bad CV joint or axle mounting bolts coming loose.

I did raise the rear of the car but there is no clunking sound in reverse or forward.

My first guess would be CV joints. With the rear wheels in the air turn the wheels back and forth to see if there is a noise.
Where are you in Quebec?

My city is Dolbeau-Mistassini.

C'est pas juste à cöté...

You could also look at the engine, see how much it shifts. Motor mount is easy to drop. 4x 15mm bolts on the bottom (nuts and studs that will likely come out together), few more on the front. Of course you need to support the engine.

You could try revving the engine (or having a friend do so) and watch for shaking/shifting.

I reraise the rear of the car and move each wheel back and forth as elgyqc suggest. The rear right wheel has more slack than the other, but no clucking sound. The clucking sound seems to come from the right. I'm thinking buying a brand new cv joint to replace the right one.

Update
 

I bought a brand new right axel and installed it, the clunking sound was a little less presen but still there. Also replace the engine mount, nothing changed. I checked under the car with a friend during almost an hour, we did not find anything abnormal. Anyone has that problem? The infamous clunking sound is more present when in reverse and it sound like metal on metal. Any help would be appreciated.

Video of the clunking sound
 

This is a video I recorded with the clunking sound.

https://1drv.ms/v/s!AmSrLd3csx6CggFAnTHv-EqsHnrN?e=qhhYSP

Do the two clicking sounds repeat, or does it just do two times and stop? Looking at the valve stem as a reference, I noticed that the video cut short just before wheel did a complete revolution after the first click started. I wanted to see if it did it again when the valve stem got to the same point where the first click happened.

I'm wondering if it's something inside the brake drum. My guess is that you probably didn't remove the rotor when you did the axle, because you wouldn't need to. But I would go there next and make sure you have no broken springs or anything loose or weird. Also look in there for rub marks between the rotating parts and stationary parts. Look for stuff like a bearing retainer bolt backing off or something. It's a shot in the dark. The other thing, if you and your friend checked to make sure nothing is hitting anything, would be the wheel bearing. But I haven't heard that kind of noise when those go bad.

piper6909 thank you for the follow up. Most of the time there are 2 clunk going back sometimes only one. I'm gonna check the brake drum as soon as possible.

Then that pretty much blows my theory out of the water. Before you spend time taking things apart, have you tried putting it in reverse with the e-brake on and power-braking it? Just put some load without the wheels actually rotating. If it still makes the noise that'll eliminate anything involving rotation, including anything in the drum. Then I'd check torque on all your suspension components and even the cover plate and look for cracks

I just remove the brake disc everything is ok for the parking brake. There are no cracks on any of the rubber suspension parts. We double Check every nuts of the rear suspension, everything is tight no slack. I dont know if I Will be able to solve this mistery.

Could it be part of the CV joint cracking while flexing?

He said he changed it.

Maybe I dont know. But it's a brand new complete axel.

The other thing I can think of is something is going on inside the differential. Since it doesn't do it when it's jacked up, the only other suggestion would be if you have a friend at an oil change shop. They have those pits you drive over and a guy is inside the pit underneath the car. See if they're willing to let you or somebody drive it back and forth while somebody's under there listening. The problem with that is that there's the damn plate underneath that covers everything up. I don't recommend driving that car with that thing off, as it's also a structural part.

elac had me doing something like that, he said raise the rear of the car and put it in reverse and forward. I did it but the sound was not there doing that. Sometimes doing a left turn at low speed the clunking sound reappear but much less apparent, it seems to be related to something in the suspension.

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elac had me doing something like that, he said raise the rear of the car and put it in reverse and forward. I did it but the sound was not there doing that. Sometimes doing a left turn at low speed the clunking sound reappear but much less apparent, it seems to be related to something in the suspension.

Yeah, it's definitely something that happens under load, so lifting it up won't reproduce it. That's why I was suggesting an oil change place with one of those pits. That is, if you know someone who is willing to do it.

It could be a loose suspension or frame part that flexes under the change in load force. Or it could be something in the diff.

Ok now I understand ''the pit'' I just booked an appointment in a garage who has a pit. My appointment is July 30, that was the closest I could get. Good point piper6909.

Could it be a ball joint? It's a 2002, so after 23 years, maybe the grease in the boot of a ball joint has dried out, and it begins to make a clunking sound, metal on metal, like mine. Anyone has experience that?

I haven't experienced ball joints making that kind of noise when they go bad. But then again, as a DIY'er I've probably have changed less than ten of them on difference cars. Not ruling that out, though. Your appointment was yesterday. Didn't they find anything?

The mechanic was not able to find the clunking sound. He said he does not have expérience with european cars. I booked another appointement with an european specialist. His shop is 1 hour and a half from me. The date is august 5, at 10:00 , thank you for the follow up.

That's too bad. Were they able to replicate the noise, at least?
How well does your e-brake hold? Have you tried going into reverse with the e-brake on, just to put load on it, but not to actually move? If it still makes the noise, you can rule out anything rotational, and concentrate on frame/suspension.
What could be happening is that the load shift going into reverse is causing some movement somewhere. It could be a loose subframe, suspension link, or even a crack in the frame.

I have done the test with e-brake it does not replicate the clunking sound.When doing a left turn sometimes it does the clunking sound. If i’m parked on small slope I unlock the e-brake without the engine running and the clunking sound reappear when the car go back.