Why won't this diesel engine start?

[jamie N]

The engine has been recently running, albeit unreliable to start. Both ProDave & I know the owner, and would probably agree that to take the engine apart to that extent wouldn't be his kind of thing.

 

[ProDave]

I am sure all he has been doing lately is bleeding the fuel lines. It went through a phase where it would only start if he bled the fuel lines, then he reported he had fixed that leak and it was running. Then last trip out it started with a bang then ran okay, and this time would not start with the symptoms described.

 

[Tranona]

That was my thought ... if injection is out of synch .... then that explains the blue 'smoke' as well.

Almost imposible to "fiddle" with the injection timing on a 1GM. It is set at the factory and the only way of changing it is to remove the pump and change the shims underneath for a different thickness. Most owners (and mechanics) would not even suss that out as the procedure is well buried in the workshop manual with a warning not to do it unless the engine is being totally stripped. I had to do it with mine because I had to refurbish the timing cover to which it is attached and damaged the shims. Fortunately was able to measure the thickness and get new ones of the correct size.

 

[Poignard]

"... last trip out it ran okay,..."

Therefore, the the timing is not out, the decompressor is not engaged, the compression was adequate (even if not optimum).

To get it running on that and previous occasions, the owner has had to bleed the fuel system each time.

There's a clue there!

Before exploring more esoteric solutions, wouldn't it make sense to sort out the fuel delivery system so that it doesn't need bleeding every time the owner takes his boat out?

 

[pandos]

Good point. As far as I'm concerned, the injection pump is off limits, as it requires detailed knowledge and precision to work on it. The engineer I did my diesel course with emphasized that a) it rarely stopped engines from running and b) that working on it required specialist precision tools and a very clean environment. The major reason for it stopping engines from running was failure to observe item b!

Not all injection pumps are very complex. After looking at this video I stripped and rebuilt mine a few years ago.

Found it interesting and informative....

Did it on the table in the saloon.

 

[PabloPicasso]

Not all injection pumps are very complex. After looking at this video I stripped and rebuilt mine a few years ago.

Found it interesting and informative....

Did it on the table in the saloon.

Sounds like a fuel issue. Something somewhere is leaking air in to the fuel line. If its been happening since the last fuel filter change, fit new filters being careful to make sure they seal well. Easy to get this wrong, don't ask me how I know.

Is the fuel pump diaphragm an issue? No one's mentioned that yet. Service kit or new fuel pump perhaps needed?

 

[kieron riley]

Don’t know where you are up to , but it would help to know the engine type. I’ve worked on lots and all of the previous posts are good advice. Another thing to consider is the exhaust ,as if this is blocked most if not all of your symptoms will occur.( It won’t start) on my boat I actually have a single lever valve that I close on leaving the boat as it dries out and can lie over and tip in many ways , once allowing water back up from the outlet flooding my engine , so worth a check. Somebody else mentioned a 1 gm10 I worked on one recently that wouldn’t start not even with the dreaded easy start, so it was off with the head to discover a piece of an old air filter between the inlet valve and the seat , fairly easy fix . Lap the valve back in and a new head gasket, alls now good . You could try putting some oil down the inlet manifold, this will help increase the compression and therefore aid starting . But the easy things are usually the best answer . With an older engine then if the engine isn’t turning fast enough it won't start . So a new battery not one that you’re mate says is really good and should be ok or one that has been in garage for months unused or one , I think you get the picture. So all the best in your endeavour. Kieron

 

[ProDave]

Well an update, he finds he has water in the engine oil, so looks like proper strip down over winter. Head gasket?

 

[LittleSister]

Well an update, he finds he has water in the engine oil, so looks like proper strip down over winter. Head gasket?

Could be head gasket, but given the history perhaps more likely is too much cranking the engine without it starting. That risks the exhaust hose filling with water and flooding into the engine via the exhaust valves. One should close the cooling water inlet if the engine does not start promptly, then open it when the engine eventually starts.

Flooding the engine with water can not only result in oil in the oil, but bend a conrod or other damage via hydraulic locking of the cylinder. (Unlike a fuel/air mixture, water is effectively non-compressible.)

 

[Tranona]

The most common issue with 1GMs is failure of the inside tube in the exhaust elbow leading to water spraying back through the exhaust valve causing corrosion and poor seating - hence low compression and poor starting. If not dealt with eventually the head corrodes and water can get into the oil.

All will be revealed when the head comes off.

PS if Jumbleduck were still on here he would give you chapter and verse from personal experience!