Disco 2 Vibration/booming sound

As it suggests this is what I've had from my 2000 disco td5. Recently had a used auto gearbox put in and all seemed fine. Last few days I've had a noise like a V8 at 2000rpm so I thought it sounds good but it's not right. Anyway after some investigation, I found out it was the acoustic cover on the engine rattling. Since I've had it, it's had the left hand bolt missing and never been a problem. Suddenly it started rattling. I took it off and the rattle is gone. Or at least I think.... maybe I'm paranoid but I think there might be a bit of a resonance at the same rpm. It never happened before so what caused it? Engine mounts? Or... another buggered gearbox? If so, why? Bad luck or something more sinister like a bent crankshaft. Any ideas?

No idea then...

Exhaust been off the box change so is it refitted correctly vibrating of something or blowing etc.....

Bent or damaged flex plate?

Lee52 said:

Exhaust been off the box change so is it refitted correctly vibrating of something or blowing etc.....

Click to expand...

I did wonder but not had a chance to crawl under yet.

freelance said:

Bent or damaged flex plate?

Click to expand...

It's a brand new flex plate. My old one was cracked, so I would hope not. If it is, then I'm concerned that something more serious is going on. What though?

Right... don't think anything is blowing. Started it earlier and had quite a bad vibration (actually more of a 'shake') which seemed to go once I selected gear. Drove down the road and it was much better. However there is definitely a vibration around 2000rpm even in park or neutral. Could this point to an engine mount? Or are there other things it could be?