My 964 has developed a rather bizarre noise and I would welcome suggestions as to it’s origin/cure. The noise manifests itself as follows:

Approx 5 seconds after starting, a loud noise occurs from the right rear quarter and lasts for approx 5 seconds. Whilst it is difficult to describe a noise accurately the best I can do would be to say that it sounds like a very loud power steering pump in operation or a cross between a vibration and a grinding. (Have checked the power steering pump and it’s not that).

The noise is much louder when engine is started from cold than when it is warm. Noise appears to emanate from the right rear quarter but it is definitely not the “normal” oil gurgling noise nor is it the forward mounted brake booster pump.

The noise cannot be heard from outside the cabin with the engine cover open.

When the noise does occur, vibration can be felt from inside car by placing a hand on the off-side wheel arch interior trim.

Occasionally when driving at slow speed (with engine warm) the noise re-occurs but at a much lower level.

When the noise occurs at start up it can be cancelled out by increasing revs to c1500.

My initial thoughts are possibly some restriction/partial malfunction of the oil thermostat as although it is still opening, it is doing so at perhaps a shade higher point on the temp gauge than before.

Any suggestions gratefully received!

Regards,

David
’91 LHD C4 coupe

 

It sounds like your dual mass flywheel has taken a dump or will shortly do so.

Do you hear a clunk/clap noise when changing gears as the clutch loads/unloads the flywheel? Can you re-create the noise by blipping the throttle from idle while in neutral? Is it a loud metallic chattering noise?

 

There have been a few posts around the chain tensioners that sound like "a chain being pulled from a metal garbage can".

 

Thanks for the responses so far guys.
Don't think it's the DMF as I had a new clutch recently and the flywheel was in very good condition. Certainly no clunking when changing gear or switching off and the transmission is as smooth as ever. Blippling the throttle doesn't recreate the noise.
"Pulling a chain from a metal garbage can" sounds too harsh a noise for what I'm experiencing - my noise is more vibration-like than chain-like.
I'm on the thermostat line of thought as the noise definitely comes from the right rear quarter where oil tank etc. obviously are and the 'stat would appear to me to be the only place where some sort of restriction in the oil system occurs which may give rise to such a noise.
Any more ideas/comments would be appreciated!

 

Any pinched lines near thermostat? Is the line from oil filter to thermostat housing original?

 

Thanks Steve bit I had several lines replaced at the end of last year (including filter to 'stat) and I have just checked that nothing appears to be pinched.

David

 

This was exactly what I experienced before my Flywheel (single mass) gave up the ghost 2 weeks ago. I had the clutch replaced a year previously and done less than 10k miles since.

 

Just as feedback to anyone who's interested - it was the thermostat.
Had it changed two days ago and the noise has disappeared.
I'm happy!

 

Aircon thermostat? Expensive to replace?

 

I think he was talking about the oil thermostat.

 

OK, thanks.
(Unfortunately I'm talking about the aircon thermostat - not so easy to fit!)

 

Yes I meant the oil thermostat and yes it was (relatively) expensive - £550 (inc VAT) fitted.
David