help my 1989 740 GL sounds like a yeti!

[zombies=fun]

Hello,
Heres the problem whenever my car is at idle or in park while running it makes this horrible rattling sound. It appears that its coming from somewhere in the exhaust system. my guess is that its coming from the catalytic converter. but I'm not too sure... Does anyone know what could be wrong and or what the best course of action would be to repair the damaged culprit.

[JOHN ROBERTS]

hi there mine was doing the same thing turned out to be rubber mounting had snaped off letting exhust vibrate aginst body hope this helps yours john

Look just below the exh manifold from inside the bonnet, theres a sheetmetal heat exchanger to duct warm air into the air intake, its a pre-heater arrangement for cold weather starts. Engine cold, at idle, hold it with your and and see if the noise stops. A lot of guys just remove and forget about it.

If its not that just follow the noise further down the line, car on jackstands and a rag for your hand.

[zombies=fun]

im tracking down 2 more jack stands to check it out. ive noticed that the sound is mainly audible when the engine is cold. Thank you for the help. : )

[stephen-in-hull]

What does a yeti sound like?

On my 760, there's a dreadful rattle when idling from under the driver's footwell. Where the exhaust passes under the floor a short heat reflector, just a half round piece of metal, like a short piece of narrow guttering, was originally mounted with self tappers (or maybe they are set screws into proper threaded bushes) up into the floor. One has rusted away completely and the other is corroding away, so at idle there's a constant tinny tinkle bonkle all the while. I can't fix, because the fastenings are in line with the exhaust.

[robtd]

does it have a towbar. mine had the very rear pipe touching the towbar bracked. very easy to sort

[MTerry]

My horrible rattle was from the downpipe heat shield foreward of the catalytic converter. It finally bothered me so much I took a big screwdriver to it and broke the spot welds and pried it off. Problem solved.

[rogerthechorister]

Yup, my 16V has a metal plate over part of the exhaust manifold, sort of frontwards and upwards of the cat. I thought that light rattle was the cat - but Volvo Mike at RKM motor Techs (Strood Kent UK) showed me by pulling it that the shield was the item rattling. It's designed to keep something varm in the keuwld Svedish vinters (possibly an air intake???), so in England you can remove the heat shield and forget it.