Diesel fuel in sump

[guelrose]

I am having a problem with my engine oil level rising because diesel fuel is getting into the sump. I have just had the injectors changed and a new fuel lift pump fitted but the problem still persists. Any ideas as to the cause of the problem?

 

Engine performs normally, does not smoke except briefly on initial starting, has done just over 10000 hours. Oil pressure drops to around 30 psi after warming up probably due to the diesel in the oil.

[PaddingtonBear]

What engine?

[p6rob]

I'm not an expert on diesels, or boats but from my experience with classic cars:

 

There aren't many ways in which fuel can get into the sump. A split diaphragm in the lift pump is the usual suspect.

Is it definitely fuel?

could it be coolant?

does the sump level rise with the engine running or overnight?

at what rate does it rise?

 

from my baptism of fire on diesels and boats:

How much cranking does the engine take to start after standing overnight?

 

Rob

[Biggles]

What engine?

 

Sounds like a Lister. A well documented problem. Take care you get this fixed or the engine could self fuel then you'll have no engine.

[The Bagdad Boatman (waits)]

One of two things. Unburnt fuel seeping down past the pistons (unlikely) a fuel leak on the high pressure system probably between the injector and the supply pipe or the return spill pipe. If it was coolant the oil would be milky. Remove the top covers and see if you can spot fuel spurting out. Oil pressure is about right and if you cure the problem the engine will have had a good clean. New oil and filters needed.

Edited August 20, 2013 by The Bagdad Boatman (waits)

[bizzard]

The thread title says ''BMC''.

[MtB]

The thread title says ''BMC''.

 

Not on my computa, it doesn't!

 

Thread is posted in the BMC board though....

 

MtB

[Tony Brooks]

I suspect it has a DPA pump on it so a 1.5, 1.8, later 2.2, or presumably a 2.5.

 

Almost certainly a leaking main shaft seal on the injector pump.

 

When we had high sulphur fuel the sulphur caused the seals to swell so they "took up" routine wear. Now there is very little sulphur in the fuel the seals are gradually giving up the sulphur and shrinking so we get leaks. I have been expecting this for a couple of years and have been warning about it and the need to keep an eye on the sump level.

 

It is easy for an ordinary boater to remove and refit DPA pumps PROVIDING the "triangular" block on the engine that the pump bolts to has a little pointer attached as per the 1.5. So you could take the pump off and to a diesel equipment specialist in your local town for overhaul. Come back if you want more info.

[DHutch]

 

Thread is posted in the BMC board though....

 

 

 

This.

[Oakie]

Take note of what Tony Brooks says. It happened to my BMC 1.5 and I had to remove the injector pump and have it reconditioned and recalibrated - not cheap, but unlikely you will find another one. No problem after that. I did change the lift pump first, but that was not the culprit.

[guelrose]

All comments noted. I have sourced a service exchange reconditioned injector pump.... All I have to do now is fit in!! Thank you all for the advice, I will let you know the end result in due course

[guelrose]

Service exchange injector pump fitted , now everything working as it should.

Thanks to TB for his correct diagnosis

[Tony Brooks]

This is getting more and more common. I think that now I would plump for this before a lift pump. However I would test the lift pump first.

 

More and more DPA pumps are going to leak fuel into the sump over the coming years so thats all BMCs from 2.5 and smaller (except very early 2.2s), Perkins 4-10x. I just hope the Bosch Rotary pumps do not suffer the same thing .