944 - God awful noise under acceleration...
Discussion
After a spirited drive thru Milton Keynes the other day involving half a dozen of so red liners in second and third suddenly there was a noise like the propshaft's about to fall off, at first I thought it was exhaust related (sounded a bit like running with no exhaust) but having checked underneath concluded that it's more likely mechanical and I wondered about the propshaft catching?! It's in a tube on these cars isn't it?
It happens at high revs under load in second and third (didn't try fourth - backed off at this point) and sounds expensive but doesn't do it unless I'm caning it. After having slowed down for a bit I can then cane it again for a bit before the noise returns.
Any ideas?
It happens at high revs under load in second and third (didn't try fourth - backed off at this point) and sounds expensive but doesn't do it unless I'm caning it. After having slowed down for a bit I can then cane it again for a bit before the noise returns.
Any ideas?
It would depend on where on the car the noise is, and what noise it sounds like. Can you be more specific?
(Don't drive it again unless you find out what it is: do a thorough visual check. If the engine is Ok, then start and rev without putting it into gear.
try to eliminate your options. It MIGHT just be somehting worked loose and catching on the bodywork...
(Don't drive it again unless you find out what it is: do a thorough visual check. If the engine is Ok, then start and rev without putting it into gear.
try to eliminate your options. It MIGHT just be somehting worked loose and catching on the bodywork...
As far as I can tell it's coming from the rearish tunnel area (oo-er?!) and I'm pretty sure the engine needs to be under load to make it happen, have tried revving when stationary.
The noise sounds like a roar, hence I thought it was a blown exhaust but knowing it's not that makes me think loud drumming noise instead.
When I'm driving normally ie commuting and not using more than say 4500rpm it isn't evident at all.
>> Edited by jaseb on Wednesday 26th May 12:53
The noise sounds like a roar, hence I thought it was a blown exhaust but knowing it's not that makes me think loud drumming noise instead.
When I'm driving normally ie commuting and not using more than say 4500rpm it isn't evident at all.
>> Edited by jaseb on Wednesday 26th May 12:53
Had a similar thing on my S2 and it was the driveshft bearings. Try grabbing hold of the driveshaft and see if there is any up or down movement in it, mine had about 3-4mm as the bearing had collapsed!!
Funnily enough it was quiet under low load. If you have to re-build the gearbox, make sure you change the pinion bearing aswell.
Andy
Funnily enough it was quiet under low load. If you have to re-build the gearbox, make sure you change the pinion bearing aswell.
Andy
I've been studiously ignoring it (easy as when driving normally it don't make no noise!) but the cat thing sounds interesting as the heat shield on mine is non existent - why would that make a noise though?! I've been thinking about de-cat'ing anyway so that might be the solution.
The other theory is that it IS the exhaust rubbing somewhere, an ex 968 owner said he had a similar thing and although the exhaust appeared to be very solidly mounted it still rubbed.
I need another go on the ramps to have a better look - next weeks job!
Was it the propshaft (engine to clutch/gearbox) that moved or the driveshaft(s) to the individual wheels that moved?!
Thankyou for all your suggestions btw
The other theory is that it IS the exhaust rubbing somewhere, an ex 968 owner said he had a similar thing and although the exhaust appeared to be very solidly mounted it still rubbed.
I need another go on the ramps to have a better look - next weeks job!
Was it the propshaft (engine to clutch/gearbox) that moved or the driveshaft(s) to the individual wheels that moved?!
Thankyou for all your suggestions btw
Jase just be careful with the ignoring 
In my limited experience things rarely get better by themselves. I have ignored faults before and every time it has got worse and then affected something else, ending up costing me double
than if I'd got the original fault seen to straight away.
In my limited experience things rarely get better by themselves. I have ignored faults before and every time it has got worse and then affected something else, ending up costing me double
than if I'd got the original fault seen to straight away.Seems like we found it, the silencer box between the cat and the rear box was just catching the bolted on cross member behind it, whipped the back section of the exhaust off and ground the lip back a little (3 or 4mm) and I now need to find time and some clear roads to give it a test, failing that new exhaust rubber should do it.
Bit of a relief as it goes, should be a cheap fix...
Will let you know how it goes on the way home this evening
Bit of a relief as it goes, should be a cheap fix...
Will let you know how it goes on the way home this evening
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