Exhaust pipes rattle under heavy, low-RPM load

[theirongiant]

Suppose for a moment that my car is in 3rd gear, climbing a relatively steep hill, traveling 15mph. You can imagine that my engine is struggling to stay alive, making all kinds rumblings, and on top of that, I hear a rattling like a large tin can coming from my car.

Sometimes I can hear it when I'm parked and idling, though not as strong. I poked around and took a few pictures of this, which is clearly the cause of the rattles: It's the outer sheath surrounding the exhaust pipe. If I move it just right, or press it against the pipe, the rattling stops.

http://img22.imageshack.us/img22/2234/exhaustthingy4us.th.jpg (http://img22.imageshack.us/my.php?image=exhaustthingy4us.jpg)

I studied the Bentley manual for a moment, and this appears to be near the "front pipe with catalytic converter." But if the cat were loose, wouldn't I see lots of black smoke pouring from under the car?

[winfred]

sometimes it's the heat shield has broken loose sometimes the ceramic brick in the cat is broken, the shield is easy to check by hand ether weld the sheld back on or rip it off, and the brick can usually be herd rattling when you hit the cat hard with your hand if bad you need a new cat

[rob101]

replace your exhaust hangers if any are broken (chances are they they are if you can stop the rattling by touching the exhaust).

[Paul in NZ]

and dont go 15 mph in third uphill

[genphreak]

and dont go 15 mph in third uphillmebbe he meant 115mph... ;)

I reckon the cat brick is dead. COvers must be spotted only where they were at the factory- ie not all round- it doesn't allow for contraction and expansion.

Are thos OE cats? I don't know 525 very well but they don't look it... perhaps they need replacement anyway. Wreckers usually have good second hand ones (having one of those handy is a cheap way to see)... :) Nick

[rob101]

mebbe he meant 115mph... ;)

I reckon the cat brick is dead. COvers must be spotted only where they were at the factory- ie not all round- it doesn't allow for contraction and expansion.

Are thos OE cats? I don't know 525 very well but they don't look it... perhaps they need replacement anyway. Wreckers usually have good second hand ones (having one of those handy is a cheap way to see)... :) Nick
they don't look like the things i have in the cat position.... but then again i think my car has a freak exhaust with no cat.

[E34-520iSE]

Suppose for a moment that my car is in 3rd gear, climbing a relatively steep hill, traveling 15mph.

No, no, no, no! Don't drive it like that. You'll kill the bottom end!

Cheers,

Shaun