We have the original never re-built Yanmar 2GM 14hp in our Yanaha 33 but it blew the seal around the hand starting shaft motoring into 30 knot plus a few days ago. Caught it by accident before the low pressure alarm went off but what a mess! Oil everywhere!
The mechanic said the rings are shot (motor can take a total of 10-15 seconds to start in cold fall weather - just before the event.. Starts instantaneously when warm. I will try checking the mixing elbow for carbon build up but the mechanic said we should get a new diesel rather than rebuild the 34 year old raw water cooled Yanmar. The mechanic easily pushed the old seal back around the shaft and the motor starts fine and runs. I am thinking that a new seal might be a temp fix. Appearently there is a lot of blowby and this is the diagnosis for shot rings. Their has been a gradual loss of usable rpm over the last 5 years before the exhaust water starts turning black. I normally like to run about 2800 rpm or a bit higher but last year could only manage 2700 rpm or a little less before their was any black in the water. Clean bottom of course. This year fall we could only manage 2500 rpm before there is black poorly combusted unburnt diesel in the exhaust water. No blue smoke. New injectors installed 1200 hours ago along with a valve grind and new seats.
It looks like we would get a Yanmar 2ym15 and it would drop in as the engine mount widths and other dimensions seem good. Has anyone put a yanmar 3ym20 in their Yamaha 33? The engine bed would need to have the length extended (use 1/4" 6061 plate? I guess would need to extend use the plate as rail to extend about 8cm (3 inches) beyond the existing bed. Just looking at the drawings. If we got a new diesel we would probably opt for the 2ym15 was it seems to be a direct replacement for the 2gm in terms of fit. New diesels are a lot of money.
Thanks for any feedback
The mechanic said the rings are shot (motor can take a total of 10-15 seconds to start in cold fall weather - just before the event.. Starts instantaneously when warm. I will try checking the mixing elbow for carbon build up but the mechanic said we should get a new diesel rather than rebuild the 34 year old raw water cooled Yanmar. The mechanic easily pushed the old seal back around the shaft and the motor starts fine and runs. I am thinking that a new seal might be a temp fix. Appearently there is a lot of blowby and this is the diagnosis for shot rings. Their has been a gradual loss of usable rpm over the last 5 years before the exhaust water starts turning black. I normally like to run about 2800 rpm or a bit higher but last year could only manage 2700 rpm or a little less before their was any black in the water. Clean bottom of course. This year fall we could only manage 2500 rpm before there is black poorly combusted unburnt diesel in the exhaust water. No blue smoke. New injectors installed 1200 hours ago along with a valve grind and new seats.
It looks like we would get a Yanmar 2ym15 and it would drop in as the engine mount widths and other dimensions seem good. Has anyone put a yanmar 3ym20 in their Yamaha 33? The engine bed would need to have the length extended (use 1/4" 6061 plate? I guess would need to extend use the plate as rail to extend about 8cm (3 inches) beyond the existing bed. Just looking at the drawings. If we got a new diesel we would probably opt for the 2ym15 was it seems to be a direct replacement for the 2gm in terms of fit. New diesels are a lot of money.
Thanks for any feedback
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