Knocking noise from rear

ML6105

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Jul 22, 2025
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Hi guys. I have never posted on a car forum before but do let me know if I am doing something wrong here. I am travelling 6 hours to pick up a 2.0 L Z3 which has only covered 44k miles. Paying £2k for it. Owner has just called me to say he’s hearing a slight knock from the rear when he goes over bumps. He says it’s because of the loose spare tire but I’m not too sure. Can someone please advise on what it could be if it’s a common issue and if I should still go ahead with the deal. Appreciate any inputs.
 

Duncodin

Zorg Guru (IV)
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Sep 8, 2021
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Location
Pontrhydyrun - in Crow Valley
Model of Z
M44 FrankenZed
It could be lots of things.

In my head would be the question why did it suddenly start knocking. Possibly it's been knocking for ages and the seller didn't want to mention it till now?

I suppose it could be the spare wheel but that wouldn't suddenly start clunking for no reason after 20+years. The seller will know if the spare has been out recently which could explain why it hasn't been put back securely.

But it could be many other normal wear and tear items. Most of them quite simple such as exhaust mounts. Shock absorbers, broken spring. But then if it's that simple why hasn't the seller fixed it. Could be something worse but, in the end, everything is fixable.

It's a 25 year old car. You're going to have to get used to things going knock and getting down on the ground to take a look.
 

BillyB

Zorg Guru (IV)
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British Zeds
Scottish Zeds
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Jul 13, 2016
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Edinburgh
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2.8 Individual Roadster
Hi. Where is the car located
 

Mike Fishwick

Zorg Guru (II)
French Zeds
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Sep 23, 2021
Points
113
Location
Daglan, France
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2.8 Roadster
The worst case would be cracking in the diff/rear crossmember area (unusual) or pulled spot welds in the boot floor (can usually be seen in the boot). Otherwise things such as the rear damper rubber mounts. As suggested, there is no substitute for looking - a vague description resulting in lots of possible answers is of little use to anyone.
 

Duncodin

Zorg Guru (IV)
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Sep 8, 2021
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Location
Pontrhydyrun - in Crow Valley
Model of Z
M44 FrankenZed
Forgot to say. Look online at the MOT history. Is it a recent MOT? Look at the advisories. Do any mention suspension components that are close to failure. It's only 44k miles you say. Confirm that mileage with the MOT history. Its a low mileage. But age still affects rubber but rubber can be replaced.

It was common for the powerful models, driven hard, to twist the boot floor causing spot welds to pop. But it's just a 2.0 so would take some pretty crazy driving to cause that kind of damage. .

If it was me I'd go view the car and try to knock that price down because of the unknown fault(s). Although, having said tbat, just personal preference, I'd look for a nice looked-after 2.8
 

Delk

Zorg Guru (III)
British Zeds
Joined
Oct 9, 2018
Points
125
Location
Hemsby Norfolk
Model of Z
Z3 3.0T
There could be alot of things and most are not that drastic. The damper top mounts are not uncommon to make noise. The diff mount as mentioned on a 2.0 at that milage would be possible but pretty rare.
 
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