Knocking / Clunking sound from Rear of my E53

[DrunkenNinja]

My previous mechanic said that my exhaust manifold would need changing after my last service cause he spotted a hole. When he test drove it after a full service he said he heard a noise from coming from the rear that confirmed the problem. (funny thing was it wasn't making the noise before I took it to him) needless to say he is no longer my mechanic, he was way over priced for an indy anyway and this time hit me with a huge bill when giving my X back to me broken in my eyes.

This problem seems to get worse lately and the noise is starting to drive me CrAzY!!! Whenever I start up in the morning for at least the first 5 minutes I get this clunking sound, it is not related to acceleration or driving over any bumps, it is just there and the sound does not appear connected to the any movement being made at the time, the sound is random with no rhythm.

The problem seems more evident when the car is cold, but it can happen at anytime. My new mechanic just took the X an MOT and it passed with flying colours and the mecanic said he could not see a problem and that it was in great condition, I was hoping he would hear the noise but he didn't.

I explained to him about the Manifold and he said it's possible that this is the problem but it was nothing to worry about and not dangerous.

I did have a blown Turbo, not long before I took to the old mechanic for the service, I wonder if this is when the problem was caused?

[nezarnuaimat]

Listen, you need to park your car close to his garage, and come in the morning to let him hear it ...

[DrunkenNinja]

I live too far from his garage, I can't do that...

[TerminatorX5]

check to see if any heat shields are loose around the exhaust system - you may have a loose bolt, screw or a nut and something is just rattling - i had an E39 that would rattle at the idle in the morning, and then it would go away - loose heat shield...

[DrunkenNinja]

It's ok when idle, it's when I first start to move that it begins to get grumpy, the longer I drive, the less noticeable it gets...

It's a good tip to check the heat shields though and I will be sure to do it this evening...

Strange thing is that it's right as rain and flew through the MOT, I am guessing something wasn't put back correctly after it's last service or the blown turbo caused a crack in the exhaust manifold that wasn't noticeable till later.

[upallnight]

Maybe your previous mechanic suspended a nut on a string and it swinging like a pendulum, somewhere underneath the chassis. Won't be the first time someone did that.

[SlickGT1]

Originally Posted by upallnight

Maybe your previous mechanic suspended a nut on a string and it swinging like a pendulum, somewhere underneath the chassis. Won't be the first time someone did that.

My body shop friend was chasing an evil knocking sound for a customer on a pickup. Forgot which it was. Remote ears were used. 3 days of labor. They cut a section of a frame rail out, inside, was a nut, on a wire with a note on it, well you found me. How about them apples?

[DrunkenNinja]

Please don't tell me stuff like that.... That's one Evil Mech...

I get the feeling the sound originates from a flexing type motion, one higher pitched clang (almost like a pop) then a lower pitched one... The sound is a clunking sound and could not be compared with the sound of a nut on a string fortunately.

Whatever this is, it's quite large and very annoying, I thought it could be the bushes but I am pretty sure they are fine...

[jaima]

Sounds like your propshaft might be a bit loose, if it happens when you
put the car into drive to drive away then I would get that checked out first.

[zetecor]

Sound similar to mine. had the subframe bushes replaced and all ok, clunked mainly on giving gas after slowing down to almost a shop. gave the odd 'pop'. Hope you find it.