Rattling/rubbing/vibrating resonance at 3000rpm - any ideas?

[edhorne]

Hello everyone

I have a strange rubbing/rattling/vibrating resonance at exactly 3000rpm +/- 100.

It seems to get worse as the engine warms up and extends up the rev range a little. It happens under load or with the car stationary. It happens whatever position the clutch is in (not release bearing?). It is more noticable from inside the car than outside. When heard from outside it is like a harsh rattle/vibration. It sounds like its coming from under the engine.

I thought it might be the aircon idler or pump so I have taken the air-con belt off this evening but that hasn't cured it.

I have recently had the tappets done and timing chain tensioned at Austecs but it does sound a little bit like the timing chain however there are no noises below this magic 3000rpm. Otherwise the engine seems to run fine with plenty of go.

Does anyone have any ideas or has had the same problem?

I will get this car sorted eventually!!

Cheers

Ed

[JensenA]

Ed - That resonance/vibration is normally caused by the fron part of the exhaust (in front of the CATS) just touching the chassis rail.

[Scrooloose]

I had something similar with one of the exhaust pipes touching a suspension arm at the rear.....

[edhorne]

Good thinking chaps. I'll check it out.

Cheers

Ed

[Tanguero]

Mine was one of the cats begining to rattle. A linked de-cat from TCS (thanks Joo!) soon cured it.

[edhorne]

Had a look on a ramp this afternoon. No exhaust fouling the chassis.

So, I had a willing assistant rev the engine while I stood underneath. It sounded like the noise was coming from the bellhousing. Maybe it is the clutch release bearing afterall, or some part of the clutch.

I will investigate further.

Cheers

Ed