Strange engine compartment rattle letting off at ~7500 rpm...

[BimmFiniti]

... solved!

I had a concerning, engine compartment rattle that came up suddenly with rapid engine deceleration when I was up in the 7000 - 7500 r.p.m. range. Oh boy, what the heck is that?

I checked the engine compartment; didn't see anything out of order. Belts looked solid, nothing was loose or flapping around. I did see a few dried leaves that I removed from the windshield cowl and the drains. Maybe that's all it was? Took it out for a test and, although things seemed a bit better, that weird rattle was still there. What is going on?

I didn't think it was actually engine related because that V8 was still as responsive as ever. Then, after scouring the engine compartment again looking for a clue, I spied the cabin air filter shrouds. Hmmmm.. Lots of leaves around... what would happen if one of them got caught in there?

Removed the driver's side cabin air filter shroud. Nothing. Dang.

OK, last chance before I have to take this in and spend some technician $ finding out what's going on. Removed the passenger-side shroud and, sure enough, there were two dried leaves under the filters! Problem solved!!

[Helmsman]

Originally Posted by BimmFiniti

... solved!

I had a concerning, engine compartment rattle that came up suddenly with rapid engine deceleration when I was up in the 7000 - 7500 r.p.m. range. Oh boy, what the heck is that?

I checked the engine compartment; didn't see anything out of order. Belts looked solid, nothing was loose or flapping around. I did see a few dried leaves that I removed from the windshield cowl and the drains. Maybe that's all it was? Took it out for a test and, although things seemed a bit better, that weird rattle was still there. What is going on?

I didn't think it was actually engine related because that V8 was still as responsive as ever. Then, after scouring the engine compartment again looking for a clue, I spied the cabin air filter shrouds. Hmmmm.. Lots of leaves around... what would happen if one of them got caught in there?

Removed the driver's side cabin air filter shroud. Nothing. Dang.

OK, last chance before I have to take this in and spend some technician $ finding out what's going on. Removed the passenger-side shroud and, sure enough, there were two dried leaves under the filters! Problem solved!!

Easy (and cheap!) solutions are nice solutions.... So, it was leaves in the passanges side microfiler box, or what did you mean mate?

[BimmFiniti]

Originally Posted by Helmsman

Easy (and cheap!) solutions are nice solutions.... So, it was leaves in the passanges side microfiler box, or what did you mean mate?

Yup, that was it. Had me a bit worried there for a while. Thought it was a bit funny and potentially useful for others driving their M3's in "leafy" climates!

[Beemdog]

Originally Posted by BimmFiniti

Yup, that was it. Had me a bit worried there for a while. Thought it was a bit funny and potentially useful for others driving their M3's in "leafy" climates!

This car is a leaf vacuum... I had some leaves get sucked in up front and then they started to poke out from the hood vent under certain conditions. Would be driving along and leaves would suddenly appear partially hanging out of the hood intake for the air box.