GS - Metallic 'Chatter' when cold

[hashluck]

I have noticed a couple of time a metallic sounding chattering noise coming from somewhere when the GS is cold. It does not seem rev related (though I do not like to rev a cold engine too much) but rather something like a heatshield or similar. It goes away pretty quickly. Will get it checked out soon but just wondered if any ideas or similar previous experience?

 

[CatmanV2]

Possibly the double skinned exhaust manifold. The welds give way. When cold they rattle, when hot they expand and it shuts up

C

 

[conaero]

Grab the AC pump and wobble it there should be no rock. It may be about to collapse.

You may want to remove the aux belt to get a better idea.

It probably idle bearing chatter on the aux belt, its very common.

 

[safrane]

Are the symptoms for 1-2 seconds when first started or more long term 2-3 mins?

 

[hashluck]

Thanks all

It lasts 2-3 minutes and I am convinced external to the engine. It does not always happen or is not always so obvious at least.

I have found a previous service advisory stating 'Slight play in A/C compressor front pulley bearing - check next service' - the same garage serviced it next time and no mention of it. Same garage has the car in at the end of the month and this looks like a good place to start.

Can the pulley/bearing be replaced independent of the whole compressor?

 

[safrane]

My AC unit had a similar report but collapsed about 1k later.

New compression is required but can be bought direct from the supplier at 1/3 of main dealer prices.

 

[hashluck]

Thanks - is it this?

http://euro-klima.pl/en/compressors/01140567-kompresor.html#sthash.mFStOwvu.gn0pQXIX.dpbs

 

[tomoshea]

I had this .... gets much less as engine warms.... for me it was the exhaust manifold double skins... they were removed and welded ... issue gone

 

[hashluck]

Thanks everyone, super helpful as always. I will not poke around too much as the car is in with the indie at the end of next week.

I shall report back then what they have to say (though the car of course will be warm by the time it gets to them hopefully anything not as it should be will still be apparent to them).

 

[Contigo]

Either variators, accumulator or the manifolds as mentioned.

 

[hashluck]

Thanks Phil. No it is not the variator noise (glad to say).

 

[hashluck]

Car went in for a health check Saturday. Pleased to say it got a clean bill of health other than the minor little items I am working through at the moment and already known about.

As for the chatter, well they could find nothing wrong. All bearings had acceptable levels of free play if any and a test drive, visual and full diagnostic check revealed nothing else of concern.

Their best guess was the heatshield making contact with neighbouring components when cold and they were able to replicate a similar noise by emulating this. This was in line with my thinking but there needed to be a fair amount of movement of the heatshield to make contact so I am not sure. In any case they have bent the heatshield back a little and i will monitor.

Major caveat here is that the car was of course really warm when it arrived with them but they did check anything and everything they thought could make a noise such as I described.

 

[tomoshea]

I will bet its exhaust manifold inner welds have snapped.

The noise is quite variable and increased and decreases no fixed frequency or noise level.... couldn't tell anything on mine. until exhaust manifold was removed...

 

[hashluck]

Thanks - that remains a good shout. I did mention it to them and they said it did not sound like it in my case but annoyingly I cannot remember their reasoning now.

 

[Contigo]

You would need a stethoscope on the manifold at cold start from under the car to say once and for all.

 

[tomoshea]

I localised mine to what appeared to be cylinder 7-8 using a long metal bar and my ear. Sounded like piston slap but wasn't there permanently - some time almost completely absent.

 

[conaero]

I localised mine to what appeared to be cylinder 7-8 using a long metal bar and my ear. Sounded like piston slap but wasn't there permanently - some time almost completely absent.

Coil pack breaking up?

 

[zagatoes30]

The manifold issue is common, my Spyder did it and the plan was to weld it as soon as we had the manifolds off which never happened whilst I had it.

 

[hashluck]

Took it for a spin this evening - it is such a cool car But the chatter was still there when cold so it was not the heatshield.

Exhaust manifold sounds most likely - can I assume that if it is the manifold then the issue is more of an annoyance than something that needs dealing with urgently?

Thanks again all

 

[BL330]

Has anyone mentioned a dead cat?
I ruined the rhs front cat at a track day when the car went into go slow warning mode.
It would rattle at low revs.
Had to replace the front pipes with Larini's.
Best investment, really freed up the breathing.