Here's the smoke level
I recently got a small 2 cylinder diesel engine. It spins over nicely and compression feels very good when turning over by hand. I had to free off the
plungers and delivery valves in the injection pump and now fuel comes through nicely and it starts on it's own. After about 2 seconds of starting
it starts to runaway, the revs fly up well beyond the rated rpm, with oil speckling on the floor and lots of oil in the exhaust, smoke is obviously
very thick. I had a block of wood and thick rags in case this happened so it was stopped before the rpms plateaued .
I've got the breather venting to air, not back into the intake so it's not running on oil mist from that source, and it's an N/A engine
so no turbo seals to go wrong. Does this simply narrow it down to valve stem seals and/or piston blow by? Anything else to check before taking the
head off? Could overfilling the oil cause it? I don't think it's overfilled but I'm not at the engine to check and won't be for a
while. I doubt it could have been stored with oil in the bores as it's burned off such a large quantity, it would have all burned off by now.
Have some runaway diesels:
Watch the chap telling porkies at 7:37
[Edited on 6-1-2014 by Benzine]
dodgy centrifugal governer?
Thanks for the suggestion, would that still explain the oil in the exhaust though? If it was revving away just on diesel i'd expect it to be a
little clearer. The gov is still something I need to check out though, as it's been sat for a good long while.
Here's the smoke level
perhaps you have a leaky injector. have you checked the throttle is actually connected correctly or even back to front. What happens if you set the
throttle half way? I'd start it and then shut the fuel off and let it burn off any excess, it may have been dripping fuel into the manifold and
ran on that. Just a few ideas
Yeah that's a bit smokey and they say diesels are better for the enviroment ^ 
[Edited on 6/1/14 by Mr Whippy]
If its revving fast enough the oil will get past the rings anyway. Or so I've been told.
quote:
Originally posted by luke2152
If its revving fast enough the oil will get past the rings anyway. Or so I've been told.
quote:
Originally posted by Mr Whippy
perhaps you have a leaky injector. have you checked the throttle is actually connected correctly or even back to front. What happens if you set the throttle half way? I'd start it and then shut the fuel off and let it burn off any excess, it may have been dripping fuel into the manifold and ran on that. Just a few ideas
quote:
Yeah that's a bit smokey and they say diesels are better for the enviroment ^
Those pictures make my windpipe itch just looking at them! I can feel the effects of diesel fumes on my lungs even following a smoky taxi from 100
yards behind it, I can only imagine what that must have been like in your garage!
Does the smoke smell of oil or diesel? If may well just be unburnt diesel due to e.g. a duff injector, and running at high RPM won't be helping things.
Yeah it was quite a lot of smoke, we got out of there sharpish. Thankfully it's a large barn with a semi-open roof with some open slats on the
side so it soon cleared
quote:
Originally posted by MikeRJ
Does the smoke smell of oil or diesel? If may well just be unburnt diesel due to e.g. a duff injector, and running at high RPM won't be helping things.
Could be the oil scraper ring stuck in the piston, you would get compression but oil can get past piston rings.
How do you switch the engine off if this happens?
The only time it's ever happened to me I stuck my hand over the air intake.
Takes some nerve not to just run away though 
overfull oil can cause runaway yes.
Update, IP is fine. I had the injectors off and had them hooked up and firing into the air. Both made a very nice spray pattern.
I took the head off and one cylinder had lots of black oil in it. Next step is to find out if it's valve or ring related.