I bought a 1983 Hunter 34 with the original Yanmar 3GMF diesel in January 2015. There is no hour meter on the motor. From the time I got it until IT happened it started right away (maybe 5 revolutions and off we go). Then I decided to maintain it...
Read carefully, because there's a quiz at the end. No math, though.
I had periodically checked the oil for level, but not examined it closely. Not knowing for sure how long it had been, I changed it. The oil that came out was very, very thick and black, and I could only get about 1.5 litres of the nominal 2 litre capacity out. I filled it with Rotella 15W40 synthetic, ran it for half an hour, then emptied and refilled it. I did this twice more (for a total of three fills) until the oil that came out looked reasonable. Not perfectly clear, but looking much more like new oil than used oil. So far, so good.
Then I decided to check the secondary fuel filter. It looked perfect, so I replaced it (using the same O-ring). Idiotically following the advice of "a guy" I did not bleed it before starting (supposedly the engine would just "swallow" the air). It started, ran for 5 minutes, and quit. I could not get it restarted that day.
The next day I went down and bled both the filter and the high-pressure pump, using the squeeze bulb at the tank, because I could get nothing to happen with the little lever at the fuel pump. I now know about the cam position and lifting the lever hard all the way; more on that later. It took quite a bit of cranking, but it started. Once it was running, it ran smoothly with no visible smoke (but again, more on that later). The day following that I got it started after a half a minute to a minute, and took it for a three hour run at 2800 rpm. It ran perfectly the whole time.
Since that time I've started it 16 times (by my log). When it's cold out, which around here is maybe 0 - 5°C (32 - 40°F) it might take a minute or more to get it to fire. Now that it's warming up (5-12°C - 40-55°F), it seems to take roughly 30 seconds to start. Given the relationship between dates and temperature, it could also be that things are improving with time, not temperature.
While cranking, there can be a hint of white smoke. When it fires, there is a cloud about 5' in diameter of very white smoke, together with a hint of oil sheen on the water, that immediately dissipates and from that point on there is no visible smoke - and it runs perfectly smoothly.
I have repeatedly bled it at both the filter and the H-P pump. I now know that I can get something from the fuel pump with the manual lever if I push hard and occasionally I have to rotate the crankshaft slightly to move the cam before anything happens. But the most I ever get is a drop of diesel fuel, maybe 1/8" across. This seems pretty paltry to me.
At the suggestion of a Yanmar mechanic (who I drove an hour to go see, because you don't want to pay for him to come to the boat, just trust me on that) I checked and reseated the O-ring on the fuel filter (stupidly not changing the d***d thing - I'll do that next). His comment was that if the engine ran for 10 minutes there could not be any residual air in the system, and if you recall, I ran it for 3 hours straight, not including the many short runs since. He did think it sounded like air, but that it was leaking in, probably via the fuel filter seal, not leftover from the filter inspection debacle. However, reseating it made no difference either.
So I've got three theories, and I'm looking for people who know far more than me to point me in the right direction.
1/ Air is leaking in via the fuel filter seal.
2/ Removing the viscous old oil and replacing it with shiny new synthetic with its lovely detergents cleaned off the deposits that were the only thing maintaining compression, and now a lack of compression is making for hard starting (remember this thing has no glow plugs).
3/ The little diaphragms in the fuel pump are shot (evidence would be my inability to get more than a drop of fuel per wiggle of the lever) and that, combined with a partial case of cause #1 or cause #2, means I don't get enough fuel to start.
Any and all help will be deeply appreciated.
Read carefully, because there's a quiz at the end. No math, though.
I had periodically checked the oil for level, but not examined it closely. Not knowing for sure how long it had been, I changed it. The oil that came out was very, very thick and black, and I could only get about 1.5 litres of the nominal 2 litre capacity out. I filled it with Rotella 15W40 synthetic, ran it for half an hour, then emptied and refilled it. I did this twice more (for a total of three fills) until the oil that came out looked reasonable. Not perfectly clear, but looking much more like new oil than used oil. So far, so good.
Then I decided to check the secondary fuel filter. It looked perfect, so I replaced it (using the same O-ring). Idiotically following the advice of "a guy" I did not bleed it before starting (supposedly the engine would just "swallow" the air). It started, ran for 5 minutes, and quit. I could not get it restarted that day.
The next day I went down and bled both the filter and the high-pressure pump, using the squeeze bulb at the tank, because I could get nothing to happen with the little lever at the fuel pump. I now know about the cam position and lifting the lever hard all the way; more on that later. It took quite a bit of cranking, but it started. Once it was running, it ran smoothly with no visible smoke (but again, more on that later). The day following that I got it started after a half a minute to a minute, and took it for a three hour run at 2800 rpm. It ran perfectly the whole time.
Since that time I've started it 16 times (by my log). When it's cold out, which around here is maybe 0 - 5°C (32 - 40°F) it might take a minute or more to get it to fire. Now that it's warming up (5-12°C - 40-55°F), it seems to take roughly 30 seconds to start. Given the relationship between dates and temperature, it could also be that things are improving with time, not temperature.
While cranking, there can be a hint of white smoke. When it fires, there is a cloud about 5' in diameter of very white smoke, together with a hint of oil sheen on the water, that immediately dissipates and from that point on there is no visible smoke - and it runs perfectly smoothly.
I have repeatedly bled it at both the filter and the H-P pump. I now know that I can get something from the fuel pump with the manual lever if I push hard and occasionally I have to rotate the crankshaft slightly to move the cam before anything happens. But the most I ever get is a drop of diesel fuel, maybe 1/8" across. This seems pretty paltry to me.
At the suggestion of a Yanmar mechanic (who I drove an hour to go see, because you don't want to pay for him to come to the boat, just trust me on that) I checked and reseated the O-ring on the fuel filter (stupidly not changing the d***d thing - I'll do that next). His comment was that if the engine ran for 10 minutes there could not be any residual air in the system, and if you recall, I ran it for 3 hours straight, not including the many short runs since. He did think it sounded like air, but that it was leaking in, probably via the fuel filter seal, not leftover from the filter inspection debacle. However, reseating it made no difference either.
So I've got three theories, and I'm looking for people who know far more than me to point me in the right direction.
1/ Air is leaking in via the fuel filter seal.
2/ Removing the viscous old oil and replacing it with shiny new synthetic with its lovely detergents cleaned off the deposits that were the only thing maintaining compression, and now a lack of compression is making for hard starting (remember this thing has no glow plugs).
3/ The little diaphragms in the fuel pump are shot (evidence would be my inability to get more than a drop of fuel per wiggle of the lever) and that, combined with a partial case of cause #1 or cause #2, means I don't get enough fuel to start.
Any and all help will be deeply appreciated.