Flow Master Help!

[Patrick]

I put flow masters on my MM awhile back. I luv the sound and it has some more punch to it. But here is the problem. After about a month I started to get an anoying rattle from the rear end, buzzing noise! I took it back and he said when tail pipes heat up they move a bit. So I when back again when the rattle came back and he said it wasnt the flowmasters, must be sumtin else!

Is thier anything I can do to fix this prob or what?????

[Logan]

If it primarily happens while the engine is under load or coming out of a load, but doesn't happen much if at all at idle, I'd bet that one of the baffles in the muffle busted a spot weld.

[jgc61sr2002]

I agree a defective muffler can give that sound.

[TripleTransAm]

Sometimes a clamp loosens and the slip-fit contact between two pipes rubs as the car hits bumps, etc. especially noticeable when the exhaust is warm. Being a long set of tubes, this friction at the slip-fit can get amplified along the tube and appear to originate from a different location, usually at the end of the exhaust pipe itself.

I just finished clearing up a similar problem on my WS6. I have the '98 specific single outlet muffler (driver's side) to which I added an unmuffled identical passenger's side tip. Over the years, the single intermediate Y-pipe-to-muffler pipe's clamp managed to loosen, and when things got hot it would result in a nasty metal-on-metal squeak/rattle that was extremely noisy and seemed to come from the passenger's side extreme rear, even though the clamp sits about even with my waist.

It took me several weeks of inspecting shock bushings, control arm bushings, muffler hangers, panhard rod bolts, gas tank straps... took apart the whole back end of the hatch interior, ripped out the spare and all hardware, even had the speakers out. Finally, I noticed a little play in the intermediate pipe slip joint as I was manually rocking the exhaust system by its tips.

So, all this to say it might be a good idea to check all slip-joints for proper tightness when heated up, and don't limit yourself to the muffler area or where it seems to be making noise... don't be afraid to look upstream.

[uwsacf]

I know on the Imps there are heat shields around the fuel tank that can get loose and start buzzing or rattling...

hth

[TripleTransAm]

The mention of rattling heat shields reminded me of the time my GTA's catalytic converter died. It made a hollow sort of rattle that was hard to track down, until I got under the car and (with exhaust cool) pounded the cat with my fist and narrowed down where the rattle was coming from.

Most modern cats are made of one or more "bricks" that look like a bunch of really long drink straws stacked one on top of the other, side by side... as they would look in a full box of straws (except they are not round but honeycomb shaped). For several reasons (lean overheating, excess fuel detonation, impact from road debris, etc) the brick may break up and a chunk or two may rattle loosely inside the converter. In some cases, the broken chunk may be expelled out the back of the converter and end up in the muffler, or may rotate internally and end up blocking exhaust flow.

[rumble]

Patrick, 3TA is right, with the exhaust cool and you under the car
either use your hand or a soft mallet to hit the muffler, cats and
pipes. If something is loose you will usually hear it rattle. I have the Flowmasters too and so far no problems.

[Patrick]

Thanks!! But another quick question. If it is the muffler, should I take to dealership or go back to where I got the flomasters put on???

And it is an inconstitant rattle. Fine on start up. Drive normal for awhile (5 min or so) sometimes starts. When it does give it gas at idle and goes away. The same when I decide to play hard. Does this help?????

[2003_MM_FYRE49]

Patrick,

I developed a buzzing noise on my MM while I wass in Colorado. It happend while the car was under load going from 2nd. to 3rd. I'll check my mufflers when I get a chance but please keep us informend of your findings. Thanks,

Tim :fire: 49

[jgc61sr2002]

Originally posted by Patrick
Thanks!! But another quick question. If it is the muffler, should I take to dealership or go back to where I got the flomasters put on???

And it is an inconstitant rattle. Fine on start up. Drive normal for awhile (5 min or so) sometimes starts. When it does give it gas at idle and goes away. The same when I decide to play hard. Does this help????? I would go back to the muffler shop.