Hey all. Noticed a buzz/rattle at 3500+ rpm in my 2003 Evo 8. Can really hear it while at the front of the car, and feel the resonance in the accelerator. Seems to be coming from behind the engine/under the car instead of around the timing area, or at the turbo -- but judging sound by position isn't the most accurate.

Looked under the car and checked things like heat shields and exhaust, all seem to be 'stable' for lack of a better term. I thought maybe a bolt was loose or something was touching something else.

Any ideas on what it could be or other things I could do to diagnose it? Here's a video of inside the car:

https://1drv.ms/v/s!AusKqMHhrFDYiNgb49hHz035_uAobg

Thanks!

 

as the driveline wears the shims, bearings and gears wear and develop lash that resonates through the cars, particularly on decel.

There is a million variables but in the end your going to do clutch TOB transfer case/front diff, transmission center/diff and possibly the rear diff before you can be 100% NVH free on a 2003.

Generally in that order, a worn twin plate clutch will do that all on its own.

 

oh damn that sounds scary. Could be in the timing belt area. Use a piece of hose to pinpoint area. Use it like a stethoscope.

 

I had the same thing and spent an evening listening and driving around trying to come to some conclusion. I even changed the accessory belt idler pulleys, good idea anyway, but to no avail. Somewhere along the line the noise went away, most likely something I did as part of maintenance or at least as part of taking things apart and putting them together again. As part of any Evo project there comes the morning spent hand fitting the plastic clippies trying to find the perfect one for each hole for a tight fit instead of the usual coming loose in a couple of days. I also still run the stock exhaust with slowly rusting off heat shields - another source of noise.

 

Double check the balance shaft belt