exhaust rattle. How log can I expect my exhaust...

[ohdaveplease]

system to last? A while back I started to hear a rattling noise (like shaking a can of pennies) when the car was cold. Looked under and found the metal bracket from the exhaust to the transmission mount broke. I removed the broken part and the noise went away. Now it's back. It seems to be the resonator but I don't want to haphazardly start replacing parts. I cant duplicate the noise when the car is on a lift. It only occurs under load. Any thoughts appreciated.
D
04 E46 325i Sport,Manual,Silver Grey/Black leather.my car
90 Mazda Miata 90k original Red with Black........toy car
01 Subaru Outback LL bean edition h6...........wife's car
past BMW's: .
88 735i e32 Black/Tan...93 325i e36 manual Electric Red/Black *my first NEW BMW!...00 528i e39 sport,manual Electric Red/Black

[Stinger9]

Got rid of an LS400 at about 15 year point and no problems from the system. But of course any part can have internal manufacturing weaknesses that greatly shorten the life.
You did not say you replaced the broken bracket?
Did you consult with a dealer who has experience with which pieces are most likely to fail first. A man with experience is always the first one I seek.

[dembooks]

your rear muffler flapper valve maybe noise?

the valve opens and closes depending on RPM, and ENGINE LOAD,
and to eliminate annoying interior droning noise from the exhaust

the valve WILL click open and closed upon startup and shut off

hope you installed a new trans/wxhaust support bracket
it's very important!

and you could have a loose/broken baffle inside
a muffler - happen often

try smacking the exhaust system with a B I G rubber
hammer to locate internal looseness

[ohdaveplease]

The weld broke so I removed the piece entirely. Is there a replacement that doesn't involve welding?
Problem seems to emanate from the front rather than the rear of the exhaust system (Under me rather than behind me)
04 E46 325i Sport,Manual,Silver Grey/Black leather.my car
90 Mazda Miata 90k original Red with Black........toy car
01 Subaru Outback LL bean edition h6...........wife's car
past BMW's: .
88 735i e32 Black/Tan...93 325i e36 manual Electric Red/Black *my first NEW BMW!...00 528i e39 sport,manual Electric Red/Black

[Stinger9]

source can be very deceptive.

And if you need a weld, bite the bullet and get some shop to do the job for a few bucks. Nothing substitutes when a weld is called for.

[JKidd]

My exhaust/transmission mount broke a while ago and I also removed it. I then started hearing another rattle. It was there at cold start up but seemed to disappear after it warmed up - it could then be heard under load (if echoing off a building).

I crawled under there several times and could hear the rattle when I'd tap the exhaust but could not isolate it. I figured it was something internal...until this last time under the car.

I spent a good 20 minutes tapping and listening - isolating location and exactly which pipe was responsible for the noise...and here is what I discovered:
While investigating, if I pushed or pulled one of the pipes, I wouldn't get the rattle. This process led me to where the two pipes come down from the engine. At this point, there appears to be a metal bracket that holds the two together (don't think it is attached to anything - just keeps the two pipes together at that point). The nuts and bolts were badly corroded but the piece itself was solid. As I wedged a screwdriver in between the bracket and the pipes to see if it was loose, I noticed when I tapped the pipe with the screwdriver there, there was no rattle. The bracket was solid and didn't appear loose in any way but wedging something there made the rattle stop. So, I wedged the screwdriver in there and pulled on it a bit (in a pseudo attempt to slightly bend the bracket). I tweaked it just enough (couldn't visually tell that I bent anything), removed the screwdriver and the rattle is gone (knock on wood).

Hope this helps.

[Longshot]

A while back, 18-24 months or so, I had a similar issue that when I was idoling the exhaust would make quite a rattle. After doing some exploratory work it turned out to be a broken weld internal to the muffler. I was just about ready to have it replaced, $750 bucks ir so, when the noise stopped. The only thing I can surmise it that whatever was knocking around in there got itself wedged and no longer is rattling.

I suggest if ya can live with it awhile to see if it goes away on its own.......

-LS

[ohdaveplease]

That sound exactly like what occurring on mine down to the clearing up on warm up. I will look into that. Thanks much. If that's it I owe you for your "diagnostic" The dealer would charge me 150 for that
04 E46 325i Sport,Manual,Silver Grey/Black leather.my car
90 Mazda Miata 90k original Red with Black........toy car
01 Subaru Outback LL bean edition h6...........wife's car
past BMW's: .
88 735i e32 Black/Tan...93 325i e36 manual Electric Red/Black *my first NEW BMW!...00 528i e39 sport,manual Electric Red/Black

[ohdaveplease]

I had my mechanic(a BMW master tech who works on the side)replace the transmission support bracket. He also crimped an exhaust heat shield and while hed had the car he replaced the oil,oil filter and belts all for a very reasonable $225 for all, parts and labor included.
No more rattle. I couldn't be happier!
04 E46 325i Sport,Manual,Silver Grey/Black leather.my car
90 Mazda Miata 90k original Red with Black........toy car
01 Subaru Outback LL bean edition h6...........wife's car
past BMW's: .
88 735i e32 Black/Tan...93 325i e36 manual Electric Red/Black *my first NEW BMW!...00 528i e39 sport,manual Electric Red/Black