My 1,9 tdi 105 makes a hollow tapping noise when idle (for the last 8 000 miles).

It follows diesel engine strokes, but not every one it is irregular, more like "thum- thum - nothing - thum - nothing - thum- thum- thum - nothing" ...

The sound is best tdescribed as if the engine would knock on something due the vibration, but it dosen't vibrate.

Doesn't matter if I press the cluch or not.

It's slightly less frequent when i turn on the Aircon (due the engine load I guess).

I have heard exact same noise on a few TDIs.

My dealer says it's normal, and he can't hear anything . It can't be normal cause it wasn't there before!

Car drives fine.

Any ideas?

Cam-Belt touching its housing? Or broken generator/waterpump/ac compressor?

Cam-Belt touching its housing? Or broken generator/waterpump/ac compressor?

I have to check the cambelt housing, thanks for the idea. .

I believe the AC is OK,

it sounds if one of the belts has a wobble, but when I look at them they are all still and do not wobble.

(except the cambelt is the only one covered so I couldn't really tell..)

I don't know the sound of broken waterpump.. any way to test it at home?

Ah yes, my car thumps when i start it, as if one of the engine mounts is bad. Maybe it is related...

Edited 28 April, 201016 yr by damok

I have to check the cambelt housing, thanks for the idea. .

I believe the AC is OK,

it sounds if one of the belts has a wobble, but when I look at them they are all still and do not wobble.

(except the cambelt is the only one covered so I couldn't really tell..)

I don't know the sound of broken waterpump.. any way to test it at home?

Ah yes, my car thumps when i start it, as if one of the engine mounts is bad. Maybe it is related...

Nope, not the belt housing.... Is there some heat shield somewhere at the center-bottom of the engine?