Rattling on acceleration

[taylormj4]

Hi all,
The 450 has recently developed a curious rattling noise on hard acceleration. It seems to be coming from right down the front of the engine bay - sounds like a metal plate rattling around or something. Can't hear it at idle or cruising or even 'standard' acceleration - so I am having difficulty tracking it down. Any ideas?
Cheers,
Matt

[alex.mcintosh]

My 500 has done exactly the same for a couple of years (maybe even from new...can't remember!).

I've had a number of things checked (e.g. brake pipes) but the dealer can't track it down...and doesn't seem to be able to hear it either!

Nothing has fallen of (yet) and everyhing still works, so I've just put it down to "one of those TVR things"

Alex

[beano500]

"Hard acceleration" you say - not "pinking" is it?

[GreenV8S]

Blowing exhaust gasket?

[rat]

This might sound daft, but check the grille on your speakers. I spent a few days worrying about a rattle that occurred most under acceleration, then found it was a loose speaker grille. Possibly because of the speaker acoustics it seemed to throw the noise to make it sound like it was coming from a completely different place. My passenger traced it actually, being better able to concentrate on fniding it than I was.

If it isn't that, there's one bolt holding the front of the exhaust to the chassis (access from underneath near to the oil sump plug). Check that's tight.

[taylormj4]

Nah, I'm pretty sure it's not pinking. I reckon its coming right from the front of the car. It sounds like a bolt rattling in its hole or a plate flapping around, really hollow kind of metallic rattling.
Who knows?
Matt

[HarryW]

Bonnet stay.

H

[xain]

I reckon it *is* pinking. First time I heard this I thought it was either the tappets (they're hydraulic! Doh!) or the timing chain rattling about. It was pinking. I used a higher octane fuel and it went totally.

Pinking isn't good for your engine. I would try and eradicate it all pretty much all costs. If you're already on 97 or 98 RON you may have to resort to backing off the timing.

[edhorne]

Sorry to be the harbinger of doom but pinking can also be caused by a weak mixture due to knackered injectors. Or at least that was what happened to me! All fixed now though, courtesy of a Mark Adams session and some new injectors.

[brushy]

i just collected my chim from h h carriages in harrogate, £2k bill but needed radiator, chassis work ,tlc and service. one thing i had noticed over the last few weeks /months was a pinking sound only on hard acceleration. very quickly identified by the experts as exhaust gaskets blowing, also saw on another forum a string of emails saying the same about the same noise. performance today much improved .good luck

[IPAddis]

Check the horns just behind the indicators. They are on fairly flexible brackets and mine had a tendency to hit the fibre-glass inner wing before I "adjusted" them.

Ian A.

[Paul]

I had exactly the same thing and it was a missing bolt on the one of the exhaust manifolds causing the engine to get very 'vocal' under hard acceleration - I spent an entire weekend making sure all the obvious potential rattles were seen to (bonnet stay, horn mounting, windscreen wiper mech etc.) when my father in law spotted the missing bolt (doh!)