Rattle from engine l.h.s. < 2500rpm

case_sensitive

Hi all,

I've had a rattle from the engine in my 1.7 Puma, appears to be coming from under the timing belt cover or one of the pulleys on the aux belt.

Video:
http://www.flickr.com/photos/43278150@N00/9540457478/

Oddly, once it starts, it only occurs under 2500 rpm or so, hold it above that, in any gear, and there's no rattle. I removed the engine cover, strapped down everything that could be loose, and even wrapped my air intake bracket in rubber.
Timing belt, water pump, and (I think) aux were changed 15k miles ago.

Video doesn't indicate directionality very clearly, but I'm certain it's coming from the left hand side.
The sensitivity to rpm though is an odd one, at 2350 rpm (I have an Ultra Gauge II for aiding diagnosis of issues) it's not there, but 2500 it starts straight away. With the bonnet open it sounds horrible.

Ideas? I'll bring it to A Man, but if I can avoid an expensive engine extraction and strip down, I'd be happier.

sebastianlieken

Sounds to me like you're hitting resonant frequency at 2500rpm for something that is lose. Wouldn't a timing belt be making noise no matter what RPM?. Curious to find out exactly what it is though.