Dockhead
Well-Known Member
My Yanmar 4JH-HTE, which has about 4500 hours, is consuming oil and smoking. It's always smoked since I first bought it with 830 hours, 17 years ago, and a series of engineers were unable to diagnose it.
The oil consumption is not ridiculous but is starting to get somewhat annoying. A litre every 30 hours I would say.
The engine seems to have very good compression as it starts very easily even in cold weather, without the preheater. I'm not even sure the preheater works, having never used it in 17 years, including in the Arctic. Develops full power and runs smoothly and sweetly under all circumstances. I follow the Yanmar instructions and run it up to redline for a few minutes, every few hours. Like that it will push my 25 tonne boat up to 9.5 knots in calm weather, so I'm pretty sure all advertised 100 horses are present and accounted for.
The smoke is greatest at startup and tapers off under load and when the engine is thoroughly warmed up. This would seem to contradict rings or bore polishing, which normally smoke more under load -- I think this is more likely to be a valve guide/valve seal problem.
Therefore I'm thinking it might be worthwhile having the head off for new valve guides and seals, and lap the valves.
Is there a good man in the Solent area who could do this reliably for reasonable money? I normally do all my own diesel engine work and so have almost no experience with the diesel engineers of the area.
Grateful for any tips.
The oil consumption is not ridiculous but is starting to get somewhat annoying. A litre every 30 hours I would say.
The engine seems to have very good compression as it starts very easily even in cold weather, without the preheater. I'm not even sure the preheater works, having never used it in 17 years, including in the Arctic. Develops full power and runs smoothly and sweetly under all circumstances. I follow the Yanmar instructions and run it up to redline for a few minutes, every few hours. Like that it will push my 25 tonne boat up to 9.5 knots in calm weather, so I'm pretty sure all advertised 100 horses are present and accounted for.
The smoke is greatest at startup and tapers off under load and when the engine is thoroughly warmed up. This would seem to contradict rings or bore polishing, which normally smoke more under load -- I think this is more likely to be a valve guide/valve seal problem.
Therefore I'm thinking it might be worthwhile having the head off for new valve guides and seals, and lap the valves.
Is there a good man in the Solent area who could do this reliably for reasonable money? I normally do all my own diesel engine work and so have almost no experience with the diesel engineers of the area.
Grateful for any tips.
