I have developed a new rattle / knocking noise on my mk3 tdci.

Car ticks over fine at 800 rpm, and no noise, other then normal diesel engine noise.

When I pull away, it has a loud rattle knocking noise but goes when I hit 1000 rpm and engine is quite. It sound like its coming from the alternator side, defo not gearbox side.
Its the same in each gear. It gets better after about 15min drive. Had new pulleys 2 year ago.

Any ideas? Only really noticed it after my new exhaust was fitted. Might be just a coincendance? Don't think its a heat shield as don't sound tinny.

Cheers

 

Alternator can have this i did once on the old XR4i

 

Are the engine mounts ok?

 

Should be dan, only had its mot done 2 weeks ago. That's when the exhuast was fitted. Would of thought it would of been spotted if mounts where loose or warn.

 

The MoT is no guarentee of roadworthyness! Worth getting them checked out as its a simple fix if it is one of them.

Get your head in the engine bay and have a good look around for anything wobbling. Look at the belt and make sure it's running 'true'. It was all swapped, but it's a Mk3 weak point.

 

Yer will have a look at the weekend, I know you did the bottom aux pulley and tensioner, but I know they do fail quite offen. Might be something silly like the plastic engine cover vibrating.

 

the belt tensioner can go "soft" and let the belt jump on tickover/drive takeup

they are a bitch to change aswell

failing that, harmonic damper (crank pulley) can fail too
had a transit in on monday, it was still "in place" but when he turned the steering all the pulleys stopped and he lost steering assist, cut the belt off as the tensioner was seized and the crank pulley fell in half when i pulled the belt!!