Diesel problem

[dickiecox]

I have a single cylinder diesel Yamar engine in my old Bobcat digger,
It's never missed a beat till recently.
Engine starts and runs ( maybe slightly over revs)
After about 15 secs it starts to black smoke and eventually dies,
Just before it stops it sounds like its running out of oil ( knocking?)
It then refuses to start again.
I have had high pressure pump and injector refurbished, and replaced all fuel lines and made sure they're tight.
I've bled the system from the pump to the injector loads of times.
Has anyone out there got any idea's??

[stevieturbo]

could be as simple as a blocked air filter.

[dickiecox]

Thanks for the reply, I have run it without the air filter and also replaced and cleaned the original one.

[powerstroke]

dickiecox said:

Thanks for the reply, I have run it without the air filter and also replaced and cleaned the original one.

Could be the exhaust blocked up !!! ive had that with a honda single cylinder,
I burnt out the carbon with a blow lamp took a while you have to realy get it hot!!! then give in a good tapping with a small hammer then whats left will blow out when you re fit it ....

[JAHetfield]

Black smoke indicates that the mix is too rich, ie either too much fuel going into the cylinder or not enough air.

Are you sure the injector pump is set up correctly? I'd also suggest taking a look at the timing.

[one eyed mick]

If it's got any age on it it is probably bu---rd , stip down ,rebuild time I think .They don't last for ever and have a hard life --my ops only

[Mr2Mike]

Could it be the hydraulic pump has a fault which is putting a heavy load on the engine? That could explain the black smoke and the knocking as it stops.

[dickiecox]

Thanks for all the help guys.
It's given me a few more things to check, i must admit i didn't consider the coking up and the hy/pump angle.
Already checked the timing and it seems ok. Last chance saloon for the engine, if my next look doesn't come up with anything it's coming out!

[Blownoiler]

That sounds like excessive blowby past the rings to me. When crankcase pressure levels get too high from excessive blowby the ventilation system (which feeds crankcase fumes into the air intake) feeds engine oil into the engine. The engine then "runs away", or starts revving faster as the engine oil burns in the chamber (well...partly burns, it's not much of a fuel) The result is lots of blue/black smoke from the exhaust, and a knocking sound to go with it.

[dickiecox]

Sounds like this could be the problem, a job for the compression tester then?