Took my boat out today and all was running fine with my 1GM10. I was keeping it at about 1000-2000rpm when all of the sudden it revs itself up to full throttle and I can't back it down or choke it out! White smoke is billowing from my exhaust and I can smell oil burning. I'm still able to throw the boat into forward and reverse, hoping that the gear change would put the engine under manageable load again. Finally after a minute or so it does back down and I can choke it out. I see oil in my bilge and some splattered toward the rear of the engine/ near the shaft but nothing really apparent showing its source. What the heck did I break???
What on Earth is going on with my Yanmar 1GM10
- Thread starter Matt Adam
- Start date
I don't, beyond the wiki's reasons for it happening at all, and their logical repair procedures.
You might do a forum search on "diesel runaway" using that little quick search box in the upper right of every page.
That sounds like a run away, but the question is why did it do it. Often a run away is due to the rings or valves leaking so much oil that the engine will run on it, but that causes black smoke and it won't stop until the oil runs out and the engine seizes. White smoke indicates too much fuel in the cylinders which points to an injection or governor problem, but why did it do it and why did it stop without destroying the engine? Could be a loose or broken spring in the governor or some issue in the injection pump. And it will likely do it again these thing don't just go away.
Check the simple stuff first. Had you checked the oil level? To much oil in the crankcase can cause that; also check for a fuel leak into the crankcase which may increase its level. After all Diesel fuel is just a thinner version of oil. A rupture in the lift pump diaphragm can cause such a leak. Should it happen again just stuff a towel or large rag into the air intake tube to shut it off. Avoid using the decompression lever.
According to Larry Berlin of Mack Boring, Yan mar's east coast distributor, a diesel runaway in a sailboat can generally be cured by bringing the boat to a flat level position so excess oil is no longer getting flung around to combust and 'run away.' ( this is a particular problem for splash lube engines which are overfilled with oil in a boat which is then put on a hard heel . ) he also suggests having a custom piece of metal handy , larger than your air intake, to put over the air intake to block air to stop combustion. trying to block with a rag is a bad idea, it would get sucked in. he advised that a piece of wood could break.
Thank you all for your help! I'm honestly not sure why engine hasn't torn itself to pieces and was able to restabilize itself afterward. I'm almost certain that this little episode just ate through my oil supply so I'll be checking that and probably replacing the filters.
Am I incorrect in thinking that I should be able to partially restrict the fuel supply by turning the supply valve part-way? Or better yet, is there a way to restrict the fuel pump with out adding excess strain to it?
Am I incorrect in thinking that I should be able to partially restrict the fuel supply by turning the supply valve part-way? Or better yet, is there a way to restrict the fuel pump with out adding excess strain to it?
I'm looking at a way to avoid future incidents more than just stopping it when it happens. That's the one thing I haven't been able to find and I refuse to accept that the only thing we can do is wait for runaway to happen and stop it.
If it is a runaway diesel, fuel is not the issue. Oil is leaking past your piston rings and igniting. This causes the engine to speed up as if more fuel was being added. As the engine speeds up, even more oil is drawn into the cylinders past the leaky rings causing the engine to run faster and faster until... kaboom. Plenty of youtube videos to google on this.
I also hope you didn't do any damage to your transmission. Slamming it into forward and reverse at high rpm can't be a good thing. The idea of a stout piece of metal to block the air intake is the best way to stop a runaway diesel, as a previous poster mentioned. Obviously you need to troubleshoot this and repair the problem first and foremost. But I'd have that piece of metal handy even after the repair, just in case.
Looking for ways to restrict or cut off fuel will not stop a runaway diesel. It is getting its own fuel from the oil in the crankcase. What I was saying about the fuel pump is that if it gets a perforation in the diaphragm it will allow fuel to leak into the crankcase and elevate the level of oil inside the crankcase. The solution would be to replace the pump.
Doesn't have to be running on lube oil. If the governor locks up full open that also is a runaway, but running on fuel oil. The fact that it stopped by itself makes me think more that direction. Lube oil runaways usually don't do that, the engine either seizes or blows up if you don't manually stop it by cutting off the air. A broken spring or crud in the governor could cause that, and be much easier and cheaper to fix than a ring job.
I know, but I have a number of people who are good wrenches to help me out. I'm just inexperienced with how diesels run which is why this whole runaway thing is foreign to me.