I have a 1990 Hunter 30 Yanmar 2GM20F that was installed in '95. It has about 600 hours on it. It has always run well except for leaving a soot on the transom behind the exhaust. Last weekend of last August we set out for a weekend cruise.....black smoke, couldn't get over 2000 rpm. No previous symptoms. Returned to the dock, pulled the mixing elbow, which was blocked except for about a 1/2 inch opening. Took it home, stuck it in a vice, and cleaned it out with a cold chisel and hammer. The engine ran better than ever... Except that after about an hour at cruising RPM, it now starts to smoke....not real black, more of a gray, not white (i.e. steam). When motoring from home for about an hour, for instance, and returning to my slip with the engine near idle, it fills the air all around. Had never done this before the mixing elbow job. This happended twice last September, and I haven't run it since except to start the engine about every three weeks, run it for about 15 minutes (always in gear, with a load on it). Today did the same. It never smokes in this situation. Just a little smoke and soot at startup, which it has always done. Put a 3 blade prop on it in 2001. I cruise at 2800-2900 rpms, don't idle much, always follow Yanmar start-up and shut down procedures. Annually change the oil and filter, and raw water impellor at least every other year---was doing it every year, but they came out looking new, so I went to every other year. Smoke=unburned fuel, too little air. I pulled the air cleaner off last time we made a run of about an hour, and it made no difference. Injectors? Something still clogging the exhaust system?
Smoking Yanmar
- Thread starter Dean Strong
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Tuff one Dean, how about water flow?
I know your impellers are good but did you make sure the soot was also removed from the area of the raw water elbow as it enters the mixing elbow. A quick check is, while running under load for a while, touch the water elbow. It should be cold. Other than that, I'm scratching,,,,,
I know your impellers are good but did you make sure the soot was also removed from the area of the raw water elbow as it enters the mixing elbow. A quick check is, while running under load for a while, touch the water elbow. It should be cold. Other than that, I'm scratching,,,,,
Hmmm.
1. Elbows hard to clean, perhaps better to replace. 2. Dirty fuel? 3. Clogged fuel filters?
1. Elbows hard to clean, perhaps better to replace. 2. Dirty fuel? 3. Clogged fuel filters?
Head Scratcher
I got the elbow very clean. And yes, it runs cool. After several run-ins with eel grass and the resulting overheating in my early years, I've developed this pesky habit of touching the elbow every 30 minutes or so while motoring---its easier than hanging one's head over the side to check waterflow out the exhaust, which can be hard to discern at cruising speed. I'm wondering if there are other areas in the exhaust system, maybe downstream from the elbow, that could have accumulated large amounts of soot before the elbow was cleaned. Anybody know?
I got the elbow very clean. And yes, it runs cool. After several run-ins with eel grass and the resulting overheating in my early years, I've developed this pesky habit of touching the elbow every 30 minutes or so while motoring---its easier than hanging one's head over the side to check waterflow out the exhaust, which can be hard to discern at cruising speed. I'm wondering if there are other areas in the exhaust system, maybe downstream from the elbow, that could have accumulated large amounts of soot before the elbow was cleaned. Anybody know?
Smoke Problem
Dean, "black smoke, couldn't get over 2000 rpm" black smoke is caused by excess load or excess fuel. If fuel is not delivered properly in a timely manner it becomes excess fuel. You may have a faulty injector dumping fuel in a cylinder, or a cylinder with low compression. Diesels are simple, atomized fuel plus compression equals power. Good Luck with the diagnosis.
Dean, "black smoke, couldn't get over 2000 rpm" black smoke is caused by excess load or excess fuel. If fuel is not delivered properly in a timely manner it becomes excess fuel. You may have a faulty injector dumping fuel in a cylinder, or a cylinder with low compression. Diesels are simple, atomized fuel plus compression equals power. Good Luck with the diagnosis.
Sounds similar to my problem...
Dean, I'm having smoke issues as well. Same vintage motor and around the same hours. Closer to white or white grey. Heavy smell of diesel, not steam. Unburnt fuel, right? Injectors tested fine. The boat is winterized now but my first step in the spring will be to trace the fuel lines for small leaks and replace my lift pump. The lift pump appears to be weeping a small amount of fuel at the diaphram and it looks like some of the copper pinch washers are weeping as well. If fuel is weeping out I assume air is coming in, right? Can anyone confirm that a small amount of air in the system could cause white/grey smoke? Perhaps this could be something for you to consider as well. I've been told that injector or high pressure pump issues with only 600 hrs would be very rare. I am at a disadvantage that qualified service people are non-existant in my area. Good luck and keep us posted on your progress. Tim Lake Tahoe
Dean, I'm having smoke issues as well. Same vintage motor and around the same hours. Closer to white or white grey. Heavy smell of diesel, not steam. Unburnt fuel, right? Injectors tested fine. The boat is winterized now but my first step in the spring will be to trace the fuel lines for small leaks and replace my lift pump. The lift pump appears to be weeping a small amount of fuel at the diaphram and it looks like some of the copper pinch washers are weeping as well. If fuel is weeping out I assume air is coming in, right? Can anyone confirm that a small amount of air in the system could cause white/grey smoke? Perhaps this could be something for you to consider as well. I've been told that injector or high pressure pump issues with only 600 hrs would be very rare. I am at a disadvantage that qualified service people are non-existant in my area. Good luck and keep us posted on your progress. Tim Lake Tahoe
Had to replace the washers
Tim, Yes, the smoke is grayer than black, but clearly not white as is the case when the raw water intake is blocked (been there) and the engine gets too hot, so exhaust water comes out steaming.... Interesting...I had fuel leaking at the lift pump when I first bought the boat in 2001. Mold in the fuel tank. Cut an access port, cleaned it out, replaced the primary filter with a Racor, but had leaks in the line around the lift pump on the block. Replaced all of the the copper crush washers (still have some on my dresser). Yet I've always assumed that if any air leaked into the line, the engine wouldn't run. It does seem certain that this is a fuel problem. It also happens only when the engine has been running at operating temperature for quite a while, more than thirty minutes, closer to an hour. Heat and/or expansion is changing something. You might want to email me through the Owner's Directory so we can stay in touch. I'm going to stay on this till it's solved.
Tim, Yes, the smoke is grayer than black, but clearly not white as is the case when the raw water intake is blocked (been there) and the engine gets too hot, so exhaust water comes out steaming.... Interesting...I had fuel leaking at the lift pump when I first bought the boat in 2001. Mold in the fuel tank. Cut an access port, cleaned it out, replaced the primary filter with a Racor, but had leaks in the line around the lift pump on the block. Replaced all of the the copper crush washers (still have some on my dresser). Yet I've always assumed that if any air leaked into the line, the engine wouldn't run. It does seem certain that this is a fuel problem. It also happens only when the engine has been running at operating temperature for quite a while, more than thirty minutes, closer to an hour. Heat and/or expansion is changing something. You might want to email me through the Owner's Directory so we can stay in touch. I'm going to stay on this till it's solved.
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