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MG MGF Technical - High pitched sound from exthaust area.


Hi all,
maybee this topic has been up before but canīt find anything in the archive.... At low revs I have a sissling high pitched noise somewhere from the exthaust area. It is not the exthaust-box or cat seals - have ruled out them after trying to listen with a flexible tube to my ear. Most probably it is further up front , a good candidate is the flexible joint between header and exthaust. The sound is indeed very irritating and reassebles very much the sound heard when there is a inlet mainfold leak .
Canīt decide if it is purely mechanical resonance or blowing gas from a tiny leak....

Any advise welcome,

Regards , Carl.
Carl

Carl, for what its worth I have exactly the same problem with my 97 VVC.
Its driving me mad. Like yourself I have gone over everything and cannot find the source. The zizzing is always there on start up and almost over the entire rev range when lifting off the throttle.
Any ideas anyone PLEASE.
Tim
H10 VVC
Tim Sanders

Ah, I think this is the sound I get as well, does it appear mainly when you lift off the gas for a bit and then goes again? I just thought it was coming from the K&N.

Steve.
Steve Childs

I think Steve is right as my car is only about 3-4 weeks old and makes the same sound. If you listen hard when you change gear it will stop make a his then sart again, sounds like a very quiet turbo!
Ashley

Definitely not from the K&N. Seems to me to be coming from the flexible joint area as Carl suggested.
Tim
Tim Sanders

I get a very high pitched vibration whilst the engine is still cool and this is due to the band that goes round the cat and the exhaust! Once hot and all the free play is taken up it goes.

Ted
Ted Newman

ok guys
My 97 VVC gurgles when free wheeling .
please try to explain it. Ive got no cat innards just the outer shell.
Lister

This more of a high pitched buzzing type sound - I used to get this but it was reduced to more or less nothing by having an extra sound deadening bracket fitted to teh exhaust system.
Paul Lathwell


Hi all,
thanks for the response ! Yes, it is very hard to define if it is a true mechanical sound or a blow -by in the system ! It have turned my car into something equiped with turbo or compressor - at least soundwise ! Steve , Tim and Ashley are spot on , just like the position of the engine moving in itīs mounts would start and stop the sound.. Changing gear or enginebraking at fairly low revs starts and stops it.The reinforcement bracket is fitted since a long time ago and also checked again..

And for You Lister - that sound is true MG sound , a bit unburnt petrol entering the hot exthaust system and making popping noises. Not making any harm - just a nice pleasant sound -donīt You agree ?

I have a few meters of heat-resistant wrap that I will use to stiffen up the flexible part just in case.
The band around the muffler is already checked and tightend to no avail.

Regards, Carl.
Carl

This thread was discussed on 10/07/2001

MG MGF Technical index

This thread is from the archive. The Live MG MGF Technical BBS is active now.