Hi

I am new to this forum, and hope that some of you guys have input to my problem with my S-Type 2,7d automatic from 2008.

I have a little experience with engines, but not much!

The issue:
Suddenly while ideling at a red light a "soft" knocking noise started.

The noise is following the engine rev. and is constant (hot, cold, high or low rev.).

It is hard to find the source of the noise, but it sounds like it comes from the bay for the engine.

The sound does not change regardless of the gear (N,D,R).

The engine runs smooth, and there is no smoke, and the engine does not use or spill any oil.

The car has 65.000 miles on the clock, and have been serviced yearly.

I am afraid that it might be a "piston-rod bearing", but the sound is not that hard, and it occourred suddenly while idle, so it hope it might be something else.

I went by a Jaguar mechanic, and he said it was the toque converter that was broken (but he seemed unsure).

Next I went by a competent automatic gearbox repairman, and he said it could not be the toque converter, because the sound did not change while changing from N to D og R, and everything (toque converter and gearbox) worked perfect.

Do any of you have an idea of might be wrong with my car?

Best regards Frederik Moes, Denmark.

 

I'd try the UK jag forum site as there are more diesels there

 

Hello Frederik,
I own a S-Type 2.7D myself and probably I know what u mean. I also hear a soft 'tock-tock-tock' from time to time. It's definitely from the engine bay and only audible when idling inside the car. When I opened the hood I could not even hear it because of engine noise.
My suspect is water pump/auxiliary belt but as I said I could not locate it exactly and since it did not increase I just 'keep an ear on it'.

Just changed all belts last week (regular interval) and it seems to be gone.

Rgds
Duke