Buzzing noise under car

[16bit]

As the title suggests I have a buzzing noise under the car - its like a high pitched zzzzzzzz of sorts. it does not seem to rise or fall with revs so i don't know if its a leak of sorts? maybe exhaust? you can't hear it that well in the engine bay so i don't think it something in there. its closer to the rear end maybe just fwd of the diff.

any ideas peeps?

[AJ]

one of the heat shields loose or just falling to bits from old age?

[16bit]

hmm could be. will have a look. any other suggestions? it only seems to happen on longer trips.

[bruce]

AHA! My second favourite problem - you have loose heatshields, very common. (Then check your spark plug leads!)

[16bit]

where are they? i dont have then on the headers as they are after market?

[jules]

Usually there's a few heat shields covering along the down pipe (yours may be after market though), as well as the cat and shields above the rear muffler. You could give the cat a bash with a rubber mallet to see if it is the issue, but the usual culprit is on the downpipe shield and the bracket that attaches the downpipe to the gearbox bell housing. It often breaks and makes a great racket.

Good luck!

Jules

[16bit]

ok it is not head shields they are all very secured and I had a good look under the car and there is nothing else that is loose.

i did however find two exhaust leaks - could that be the cause of the noise?

[jules]

Plug them and find out!

Rattles can be a pain. I remember Garry once finding a rattle in the soft top that he had been chasing for ages, as it sounded like it was coming from the glovebox.

Sometimes the bonnet hinges rattle and also the boot can be an area where the sound transmits elsewhere.

Buzzing however is usually exhaust/cat related. Can you replicate it by popping the bonnet and yanking on the accelerator cable?


Jules

[bruce]

Yup, the baffles in the muffler could be vibrating a bit, with the noise coming out the leaks.