For months I've heard this tiny rattle from the back of my MC40. It's gotten much worse! Now after the car warms up, I hear a 'marbles in a can rattle. Happens at idle for 10 secs then goes away. Initial acceleration it rattles the shuts up by 2k... I've taken out the heat shields & battery shield. Isolated to INTERNAL right muffler! Had anyone encountered this? My R53 MC40 JCW has original 42k on it... Thanks everyone, Jim Rossier, 2004 JCW MC40...
Not joking - but could the neighborhood kids have put marbles or rocks in the exhaust? As a kid I used to put pebbles in my mom's hub caps, used to drive her nuts - good times.
Yeah, baffle broke loose in mine and did pretty much the same thing. I recently replaced with a Milltek.
I love my miltek but even it has had a problem with a pre-warmup rattle just behind the engine...the gasket is bad but is no problem at all once the engine warms up and seals the leak