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Noise on starting...

C

channella

PCGB Member
Member
Someone has installed a tin can with gravel inside at the rear of my car...

About 5-10s after starting from cold I get a sound like a tin rolling with gravel in it, in two bursts of about 1/2s each. The sound seems to coincide with first the auxilliary equipment starting (i.e. Aircon) and second the fast idle choke coming off a bit: so it sounds when the revs drop to a certain point suggesting something is vibrating. As I move off (either forward or backward) and the revs drop again (tend not to use the gas, just the clutch in the garage and car parks) I hear the sound again, for longer this time, until the speed (revs) pick up. Once the engine is warm this doesn't happen at all, suggesting heat expansion stops the part vibrating.

Candidates are heat shield or exhaust. The noise is from right rear. If it was the heat shield, I would think you might get it with a warm but rested engine on restart (cold shield). So I'm thinking exhuast, possibly the Cat? Any other ideas?
 
reckon you're spot on with the culpret being the exhaust. My 944S2 is doing exactly the same thing since Xmas . It rattles like a can of nuts and bolts for a second or so when I pull away at low revs. I guess its going to have to go up on a ramp to be sure [;)]
 
ORIGINAL: boxster27

Someone has installed a tin can with gravel inside at the rear of my car...

About 5-10s after starting from cold I get a sound like a tin rolling with gravel in it, in two bursts of about 1/2s each. The sound seems to coincide with first the auxilliary equipment starting (i.e. Aircon) and second the fast idle choke coming off a bit: so it sounds when the revs drop to a certain point suggesting something is vibrating. As I move off (either forward or backward) and the revs drop again (tend not to use the gas, just the clutch in the garage and car parks) I hear the sound again, for longer this time, until the speed (revs) pick up. Once the engine is warm this doesn't happen at all, suggesting heat expansion stops the part vibrating.

Candidates are heat shield or exhaust. The noise is from right rear. If it was the heat shield, I would think you might get it with a warm but rested engine on restart (cold shield). So I'm thinking exhuast, possibly the Cat? Any other ideas?
Click to expand...

I have the same sound but I only get it when pulling away from a stand-still or low speed. I have checked the shields, exhaust and their fittings and none of it moves.

I have seen reports of the cats rattling but if it is one of them I'll put up with it until they need replacing for emissions.

One other candidate may be the backing plate for the brakes as the noise is very similar to that made by a pebble trapped between the disk and the plate.
 
I had exactly this on a '99 2.5 Boxster. It was a heat shield around the exhaust pipe and according to my indie it is nothing but a dirt trap that they remove and don't replace. That was exactly what I did! End of problem
 
ORIGINAL: robbosliding

I had exactly this on a '99 2.5 Boxster. It was a heat shield around the exhaust pipe and according to my indie it is nothing but a dirt trap that they remove and don't replace. That was exactly what I did! End of problem
Click to expand...

It's there to stop the contents of the rear boot from being incinerated.
 
Yeah i'd definatly go for the heat sheild over and around the exhaust, and not the normal heat sheilds.

I have just had the same problem, only to be told that it was the cat that had gone.

That heat sheild is only held on with a bit of welding, and therefore is most probably that. Cheap and easy to fix, cheaper than 1000 plus vat for 2 new cats!!

Good luck
 
glad you found the culpret Andrew.rattles are so annoying in an otherwise quiet car. I must get mine up on a ramp sometime soon and find the source of my rattle.
Thanks for the closure
 
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