Here are some symptoms and info on my Yanmar 2GM20 in a 1988 Hunter 28.5. This may be obvious to some but I'm new to this so I'm stumped. Any advice would be appreciated. Engine was rebuilt a year ago. Lightly used, I'd say 10-20 hours since. Was motoring out of the marina last week. Heard a "pop" and engine began making a much louder exhaust noise. Later I noticed that the engine exhaust came back throught the port side scupper hose !? Engine appeared to lag and not respond to higher RPM ranges above 3000. 1/4 mile down river the oil pressure light came on and I imediatley shut down the engine. Earlier that day when I checked my oil it was clean and clear. After this episode the engine oil was black. Any thoughts to share?
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Check Out The Yanmar Forums:
http://forums.torresen.com/sailing/ or http://www.freeboards.net/?mforum=yanmarhelp
http://forums.torresen.com/sailing/ or http://www.freeboards.net/?mforum=yanmarhelp
The black oil sounds normal but the pop is not
It sounds as if part of the exhaust system failed from excessive back pressure. That means fumes where they shouldn't be and also water where it shouldn't be. Check everything below right away.
It sounds as if part of the exhaust system failed from excessive back pressure. That means fumes where they shouldn't be and also water where it shouldn't be. Check everything below right away.
Like Fred said: black is good, pop is bad.
Diesel engine oil will turn black very quickly. That is the diesel animal. The pop and engine lag is not good. Who did the engine rebuilt? If it only has about 20 new hours on it, they should still be responsible for it.
Diesel engine oil will turn black very quickly. That is the diesel animal. The pop and engine lag is not good. Who did the engine rebuilt? If it only has about 20 new hours on it, they should still be responsible for it.
Snap, Crackle, POP!
Ecipro, Like these guys rightly said, diesel turns black immediatley. Had a similar experience last year with a Yanmar in a Tarton 34, doubt if that is yours unless you have TOO MUCH oil; calle making oil. When the disel fuel is leaking into the pan. Water in you fuel will cause your problem or it is an injector problem = POP! As JC told you if it has been rebuilt, don't touch it, go back to them with it they should go good for it.
Ecipro, Like these guys rightly said, diesel turns black immediatley. Had a similar experience last year with a Yanmar in a Tarton 34, doubt if that is yours unless you have TOO MUCH oil; calle making oil. When the disel fuel is leaking into the pan. Water in you fuel will cause your problem or it is an injector problem = POP! As JC told you if it has been rebuilt, don't touch it, go back to them with it they should go good for it.
the rest of the story
Rest of the story. Problem was a blocked raw water intake. Could not notice the problem since the exhaust on this boat is UNDER the transom and you cannot tell if your expelling water and air or just air. Symptom to look out for is loud exhaust noise and air blown back through the scupper hose. ( a weird feature of this model is that the scupper hose exists UNDER the transom at the same point as the exhaust hose. If you'er not expelling raw water you have excessive exhaust air which forces it's way back up the scupper hose). Lastly, due to no raw water flow I fried my impeller gear into a million pieces. Lack of cooling caused engine warning alarms. Since I shut down the engine right away after hearing the alarms, no further damage resulted. Also needed to back flush pieces of the impeller out of the cooling hoses in the engine before all was OK. Also checked mixing elbow also to see if all clear.
Rest of the story. Problem was a blocked raw water intake. Could not notice the problem since the exhaust on this boat is UNDER the transom and you cannot tell if your expelling water and air or just air. Symptom to look out for is loud exhaust noise and air blown back through the scupper hose. ( a weird feature of this model is that the scupper hose exists UNDER the transom at the same point as the exhaust hose. If you'er not expelling raw water you have excessive exhaust air which forces it's way back up the scupper hose). Lastly, due to no raw water flow I fried my impeller gear into a million pieces. Lack of cooling caused engine warning alarms. Since I shut down the engine right away after hearing the alarms, no further damage resulted. Also needed to back flush pieces of the impeller out of the cooling hoses in the engine before all was OK. Also checked mixing elbow also to see if all clear.
Thanks for the update.
That pop description threw us. In retrospect do you think it was that pronounced? Don't feel like the Lone Ranger with your plumbing. Mine is setup the same way. I solved the cockpit scupper smoke problem (when stationary) by using a longer drain hose for the side next to the exhaust. It usually has water in it that acts like a household toilet or a sink trap. (we run our engine while stationary for many reasons)
That pop description threw us. In retrospect do you think it was that pronounced? Don't feel like the Lone Ranger with your plumbing. Mine is setup the same way. I solved the cockpit scupper smoke problem (when stationary) by using a longer drain hose for the side next to the exhaust. It usually has water in it that acts like a household toilet or a sink trap. (we run our engine while stationary for many reasons)
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