c270cdi "thumping"

[sixpack]

Hi forum
My 2002 c270cdi makes a kind of thump thump thump sound, at crankshaft speed. Its worst when cold and almost disappears after about 3 miles warm up. When hot, it does it under acceleration. Excuse the description but Ive never heard this sound before. Idle is OK, power is OK, it goes like stink, and economy seems OK. I thought possibly an injector because the noise is not present if you take your foot off the gas. Ive tried listening to all 5 injectors, they all sound the same but Im probably just hearing the sound of the solenoid operating. No warning lights show but I havnt had it to a dealer to look at codes. Anyone had this before ?. I was thinking of unplugging the power to each inj. in turn to see if I could isolate it further but would this be safe, or cause a fault code. Any comments welcome.
Peter

 

[television]

Is this a Valeo problem, sounds like it could be.

 

[sixpack]

C270cdi

Hi Malcolm
Do you mean the radiator/trans fault ? Ive heard of this problem, but I cant remember anyone describing the symptoms. Anybody had this?

Peter

 

[television]

Hi Malcolm
Do you mean the radiator/trans fault ? Ive heard of this problem, but I cant remember anyone describing the symptoms. Anybody had this?

Peter

The only symptoms are Humming,droning and / or jolting during gentle acceleration at engine speeds between 1200 and 2500 rpm.

If the car has been modified the is a white sticker on the oil cooler

203 with engines 111,112,271,611,62 and 646

 

[Ultymate]

Don't disconnect an injector whilst the engines running the injector will go wide open flood that cylinder and can cause a hydraulic lock causing serious engine damage

 

[sixpack]

cdi

Thanks ultymate, didnt know that. So is there a way of isolating a single injector on a common rail engine to trace faults ?

Peter

 

[Uncle Benz]

I have found that the management will not allow the car to run if an injector is unplugged. I didn't unplug myself - car arrived on transporter with one plug fallen off. The plugs and wiring get in to a terrible state if injector seals are left leaking for ages!!

Valeo problem a good suggestion! Also take a close look at the crank pulley for separation of the rubber interlayer.