Technical Diesel In Sump

[aj113]

My JTD is blowing black smoke and has just failed its MOT on this. The oil level rises over a period of weeks/months and the oil itself gets thinner over this time period which means that diesel is finding its way into the sump.

The car runs perfectly, even the mpg is not bad - I recently got 39mpg on a long run at 60mph.

Anyone had this problem before?

The garage is going to empty the sump, replace oil and filter and re-test - hoping for the best, but with no promises. They said that it is conceivable that the car is uneconomical to repair, considering that there is no clue as to how the diesel is getting into the sump. I understand - and agree - with that, I just wondered if it was some sort of known issue with Multiplas.

 

[Ffoxy]

Unless anyone with more experience says differently, I think the only way the fuel can get into the sump is from the cyliders unburnt... past the piston rings, which might indicate an issue with the injection timing maybe? Had a cambelt replaced at any time recently?

Many miles on it & good full service history?

 

[aj113]

Unless anyone with more experience says differently, I think the only way the fuel can get into the sump is from the cyliders unburnt... past the piston rings, which might indicate an issue with the injection timing maybe? Had a cambelt replaced at any time recently?

Many miles on it & good full service history?

Yes, looking at logically the plumes of black smoke from the exhaust can only mean one thing to me - unburnt fuel, which in turn means that the fuel is getting past the rings. Of course, I suppose the rings could be worn.

Mileage is not bad, 75k. There is some service history but no indication of a cambelt change, although I doubt that the original cambelt is still in place after 75k miles.

 

[Ffoxy]

Yes, looking at logically the plumes of black smoke from the exhaust can only mean one thing to me - unburnt fuel, which in turn means that the fuel is getting past the rings. Of course, I suppose the rings could be worn.

Mileage is not bad, 75k. There is some service history but no indication of a cambelt change, although I doubt that the original cambelt is still in place after 75k miles.

If you're sure its diesel getting in there (hard to be certain unless you take a chemical analysis of the oil) I dont see how diesel can enter the sump any other way.... on the cambelt side of things I'd seriously check it out or if it does bust that could be the end for the car, 4 years or 50k miles is a better period than Fiats recomendation, I had mine swapped at 50k & 3 years. Water pump hadnt been complaining or leaking but there was play in the bearing which would have affected belt tension.

 

[aj113]

Curiouser and curiouser.

After a change of oil and filter, no difference was noted on the emissions test. The guy at the garage had a hunch that the particulate filter was not operating properly, so he took the car for a damned good thrashing up the local bypass, and tested it immediately on its return. The result was astounding (his words) as he was previously on the verge of advising me to buy a new car. Now the emissions are all well within the permissable limits.

This of course does not explain the diesel in the sump problem but I think t shows that the emissions and the oil are two separate problems.

The point is that I am going to get my car back tomorrow with 12 months' ticket on it