Diesel Engine Vibration problem

[Chris]

.....Not a boat engine however Im hoping one of you diesel heads might know...

I am having problems with my Passat V6 diesel which has 85000 on the clock and is 3 years old.

The engine has developed an annoying vibration which I am being told may be a missfire due to Pump or Injector issues. The vibration happens pretty much all the time at idle the engine feels slightly lumpy then as you accelerate it becomes a noticeable thrumming vibration. It happens on overrun as well and also when in neutral and stationary so is definately not a gearbox issue.

The car recently had a cambelt change and since then the problem occured then went away for a week and is now back again, so I don't think the timing or cambelt is at fault otherwise it would not have gone away for the week.

The car also had a full service at the time including filter change so I am hopeful that a fuel blockage is the culprit

Any other ideas?

Chris

[doggypaddle]

is it down on power at all? if it was a miss fire i would expect you would have noticed a drop in power. Have you checked the engine and exhaust mountings? nothing rubbing the body? V6 engines are inherently unbalanced and will transmit more vibration to the bodywork than a straight 6 or a v8 though i guess VAG use counterrotating balancer shafts to combat this.
i suppose it could be a slight missfire maybe caused by air in the system, any visible damp patches on fuel system where air could get in?

[mdt]

hope you have a blocked injector. Have this V6 in my Audi and the pump went no warning at all £1200 for the part + vat

how many miles has it been doing this for ?

have you not got any fault codes poping up when it is plugged in ?

[Chris]

It still pulls ok however it may be down on power a little, not to sure. No air leaks can be detected. It has only been doing this since the service so about 500 miles now.

I am hoping its not the pump also MDT as the best price I have had so far is £800 for a recon unit.

I am taking it to a diesel specialist who will test the injectors etc. so hope to have more info tomorrow.

Chris

[9D280]

I assume if itls 3 years old it's a "common rail" (i.e electonic injectors as opposed to the pump doing all the work). If so try unplugging them all, and check the contacts / spray some WD40 (other types of "save the world" oil are available ) in & reconnect. I know dozens of petrol cars with "faulty injectors" when in most cases the plug had worked loose or similar.

[DJL]

The DMF could be failing/failed. Does the engine rattle when you switch off or do you get more vibration as you let in/out the clutch?

[Nos4r2]

It's worth chucking a whole bottle of diesel redex injector cleaner into 1/4 tank of fuel. It'll smoke a bit but if there's crud in there it'll clean it out quite well.

[Chris]

DJL there is no rattle and letting the clutch in has no impact

NOS I am going to bung in some redex and give that a go.

chris