Strange Buzz and Vibration - 2500 - 3000 rpm

[over_the_hill]

As the thread title says.

I was out yesterday and developed a strange buzz / vibration - sounded like something metal was a bit loose but only between 2500 - 3000 rpm so likely a resonance of some sort.

It sounded like it was right behind the radio at the back of the engine bay.
If I dipped the clutch while in that rev range the noise stopped.

Otherwise the car was performing as normal.

Any thoughts or ideas on what to look at - another job for the weekend !!

[WokingWedger]

Could be the dash top itself.

I have the same problem and have(just yesterday) removed the dash top and it went away.

I have now fixed the top back with velcro and will soon be out for a drive to see if it is fixed.

[OleVix]

Beware! Thats probably pinking from too much advance on the dizzy. Or you are running very low octane fuel, but probably timing related. Loosen the dizzy, turn it slightly clockwise (1-2mm), tighten, and go for a drive

[ClassiChimi]

^^^^ that's an alarming yet intuitive post,,, I heard the very same metallic tap that can only be pinking on a modern Ford earlier,,
The sounds reminiscent of a light hammer tapping the top of the Pistons,, under slight load in the same rev range as described,,
It should be obvious to someone who recognises that sound so if your not sure get a mechanic to listen,

Could be fuel regulator whining maybe?

[OleVix]

I had the same and couldn´t understand what that sound was.. same rpm range, 2500-3000. A friend of mine who is very seasoned heard it and told me at once, thats no other thing than detonation

[ClassiChimi]

It's one of those noises that once you've heard and felt it you will always recognise it,,, something to do with the fact it's so bad for your engine maybe.

I always cringe in engine sympathy when I hear that noise,,,

If it is pinking or pre detonation and the dizzy move doesn't cure it I'd then suspect Cardon build up on a valve or somewhere that's then getting hot and ignighting the fuel before it should.