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Strange banging / knocking.

Posted: Thu Aug 25, 2011 9:22 pm
by TomLS
Recently, my moggy has developed a strange rpm-related rattle/knock/bang when travelling at low speed.
When idling in neutral, if I place my foot flat on the floor, I can feel something banging irregularly against the chassis somewhere.
At higher rpm's the noise isn't there (or just can't be heard?).
I've tried looking under the bonnet and I can't isolate the source of the sound, it sounds a bit like a loose fan blade banging a metal part, but my fan is bolted on tightly.
It has increased in severity since last weekend's 370 mile round trip to V-Festival in Staffordshire (which she handled without serious complaint :D )

Has anyone had a problem like this before?

Thanks in advance,
Tom.

Re: Strange banging / knocking.

Posted: Thu Aug 25, 2011 9:50 pm
by bmcecosse
Worn out clutch thrust bearing/problem with the clutch pressure assy (release plate out of true)/gearbox input shaft not held securely in the crank tail (ie bush missing or disintegrated\) - or just the exhaust banging against the body - or the trolley jack rattling about in the boot.......

Re: Strange banging / knocking.

Posted: Thu Aug 25, 2011 10:17 pm
by TomLS
I think the noise is a bit too metallic to be the gearbox input shaft.
Now that you mention clutch plate being out of true, I did notice today (for the first time) a judder when I pulled away a more sharply than usual at a roundabout - perhaps the clutch cover bolts could be loose?
I had thought about and checked the exhaust banging, but can't see anywhere hitting and the noise still occurs.

Thanks for the reply

Re: Strange banging / knocking.

Posted: Fri Aug 26, 2011 9:42 am
by MarkyB
Does it only happen when the car is moving?
I check that the master cylinder bolts have their heads toward the torsion bar, they can touch it if the other way round.