Hi,

After accelerating my volvo v50 2006 diesel it started to make a hard knocking sounds. I'm trying to locate the sound, and from what I can hear it sounds to be coming from the top area of the engine. The sound is there at all times even when idling. It increases proportinal to the RPM. There is no noticable power loss or smoke.
I have three theories on the cause, which are:

1) The tensioner on the timingbelt has lost som of its ''tension'' and the belt skipped a tooth or two. The timing belt, tensioner and waterpump were all changed 70k km ago. This seems unlikely.
2) On (or more) of the injector are broken and needs to be replaced. The injector is injecting too much fuel and the explotion from this is what's making the sound.
3) Some bearing are broken.

Does anyone have a suggestion or clue to what this sound could be?

 

The description is awfully vague to try to make any specific guesses. Plus, in the US we're not too good at diagnosing diesel variants, since we get so few of them (sadly).

A bad motor mount can cause a pretty loud knocking noise, as you get metal-to-metal contact every power pulse.

I'd highly recommend a (very) small investment in a mechanic's stethoscope - that can really help you find the source of a noise in the engine compartment.

 

I do not think it is a motor mount thats bad since the sound is there at all times. Its not like a metal to metal sound. I'll buy a stethoscope tomorrow and try to locate it more specific.