Yanmar 2GM20 problems

[farotherside]

it's always tiny things that add up to big problems, isn't it?

(tl;dr: my 2gm20 will start with one cylinder decompressed, but immediately dies when I put the compression lever back into the normal position. help??)

a friend tried to start my engine like a car, by turning the key and applying pressure to turn it further, not knowing to turn it a quarter-turn and then use the "start" button. this bent the key, and broke something in the keyway, so now the electrical portion of the keyswitch only works when the key is in exactly the right position.

unbeknownst to me, this also disabled the alarms. :/

so! I'm sailing south from San Diego to La Paz, BCS, and we're on the last 50 miles, a hard bash north from Cabo San Lucas up into the Sea of Cortez. we're exhausted from a long passage, so we're running the engine at about 2600 rpm for twelve hours or so, when the engine starts to drop in rpms. sounds exactly like fuel starvation - I check, and lo and behold the filters are full of skunge, probably from the diesel we bought at Bahía Tortugas. :/

...but then I discovered the keyway was off and that the engine had been drinking oil, and was now quite low... like, nothing on the dipstick. I added a few litres of oil and it came up to about half, so it wasn't run *out* of oil, but it was definitely low, and the pressure alarm was likely sounding.

anyway. now the engine wouldn't start. after figuring out that it *would* start with one cylinder decompressed, I took off the valve cover, and, under the advice of a good friend, ran the starter with the injectors cracked and watched the valves... there was a sharp chirping noise from one of them. I used a tonne of Aerokroil and tapped the rocker lightly with a hammer, and the chirping went away, and now it looks like all the valves are moving the way they should.

...but the engine still won't start with both cylinders compressed! if I start it with one cylinder it starts and runs, but then as soon as I throw the compression lever on the other cylinder it dies fast, like within 2-3 seconds. I'm at a loss here - it can't be the injector plugged up, right? since the engine would stay running if once cylinder weren't firing, it would just be a lot less powerful, correct? what could cause this?? where should I look next?

help me, Obi-Wan, you are my only hope.

[Boatguy30]

One thing that stands out to me is I believe those engine hold about 2.7l of oil total. You say you put a few in and got to 1/2?

[Mainebristol]

Ok, I'll bite.

I have one of these. Quite simply, unless something is really wrong, they don't drink that much oil. Maybe a quart between oil changes, which is fifty hours or so. But really, not even that much. This is a high compression engine with tight rings, and in the two cylinder version, there just isn't that much going on.

Without more detail, it is tough to know, BUT... When you throw the compression onto the second cylinder, you add a lot of work for the one firing cylinder to do. If the second cylinder won't fire, then the work of compressing the air in it could be too much for the first one to overcome. The non-firing cylinder could have a clogged injector (we hope) or the low oil event could have worn the rings or scored the cylinder, and now the compression is too low for it to fire. Or something else. Anyway you cut it, I think your engine needs two things, at least.
1. A functioning panel with a starter switch that works. These can be had, for not too much beer money. You need working alarms, obviously.
2. Some serious TLC . Either get the manual and a good diesel book as well as some way to test the compression, or prepare to spend some real beer money on a shop to fix it for you. If the injector is clogged, let a shop clean it and test it.

Sorry, know that it's a kick in the pants, but that is my inexpert opinion. Worth very little.