deisel power

[Barry]

I am getting black junk from the exhaust when I rev the engine. i have a yanmar yse12. The boat has been sitting for about two months without starting it. Also, the engine will let me throttle up in neutral, but not in gear. No power at all. I noticed some growth on the prop. Would that make the difference in revving up and account for the lack of power? thanks for amy help we have an H30 1975 vintage.Stumped,Barry

[Bryan C.]

Growth on the prop particularly and on the bottom in general will definately rob power (or more accurately performance) and cause the engine to smoke due to the excessive strain on the engine. Clean it and I bet you'll see an improvement. The black smoking at full throttle may indicate some carbon build up. Deisels need to be run regularly at about 75% of rated RPMs ... regular running at low RPM causes carbon build up which may be what you are seeing when you rack it up. When I bought my '88 35 1 1/2 years ago, the previous owner had never run the motor at over 2000 RPMs (for an engine rated at 3400) He thought it was bad for it but the opposite is true. Consequently, for a while, when I ran her at over 2000, it smoked terribly. Over a period of time, running at higher RPMs, the smoke cleared out. I now run her at 2600-2700 and its virtually smoke free. Before I shut her down, I rack her up for about 3 seconds to blow out any build up. I believe this is Yanmar recommended procedure. The engine runs much less smoky than before. However, if your engine continues to lack power even with a clean prop and bottom, more severe coking of the exhaust system may be indicated which will need to be cleaned.

[George H260]

My old boat came without a tach, and I think I'm running at too low RPM to keep the noise down. About what percentage in terms of total throttle lever movement would you say is the equivalent to the correct higher RPMs you mentioned?

[SCA]

My 1977 H30 was having the same problem with the YSB12. Turned out to be barnacles on the propeller and old fuel.Cleaned barnacles off the prop and added Valvtech deisel conditioner and new fuel. Seems to run great now.

[Bryan C.]

Hard to say exactly how much throttle to back off to get to 75% so you have to guesstimate based on throttle play and engine pitch. If you take the amount the throttle lever moves (after taking out any play due to slack cables, if any) and back off 1/4, you're probably in the ballpark.

[George H260]

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[Fred Moore]

When you have a buildup of barnicles on the prop the engine will smoke (black) running overloaded. Clean the prop, another benefit is that you will no longer have black buildup on the transom.. Fred

[Sam Schoolfield]

It drives me crazy! Every time I come home from a great day of sailing in my wonderful old Hunter I get at least a handful of people at the dock telling me my engine is smoking. It only does it when I'm backing into my slip - maneuvering at high power setting. The 1979 Yanmar 12 seems to run great - should I be concerned?

[Steve Dion]

Basic rule of thumb for color of smoke:Blue - Burning oil

[Steve Dion]

Basic rule of thumb for color of smoke:Blue - Burning oilBlack - Excess FuelWhite - Steam (like overheating)Brown - Dirty fuelOther colors - ? (you be the judge)

[LARRY]

FIRST MAKE SURE YOUR PROP IS CLEAN AND YOUR SHAFT TURNS FREELY.YOUR ENGINE HAS AN EXHAUST MIXING ELBOW, IF THIS BECOMES CLOGGED YOU WILL EXPERIENCE SMOKING AND LOSE OF POWER WHEN IN GEAR. THE ELBOW HAS A LIFE EXPECTENCY OF 6 TO 8 YEARS THEN IT SHOULD BE CHANGED.WITH YOUR FUEL INJECTION SYSTEM, YOU SHOULD THROTTLE UP SLOWLY WHEN GETTING UNDERWAY. THIS WILL ALLOW THE ENGINE TO BRING IN ENOUGH AIR TO BURN THE FUEL AND REDUCE THE SMOKING CONDITION. THIS IS NOT WHAT IS CAUSING YOUR LOSE OF POWER.IF YOU STILL HAVE A STEEL WATER LIFT MUFFLER, THAT COULD BE RUSTED OUT INSIDE AND RESTRICTING YOUR EXHAUST. CHANGE THE MUFFLER.SINCE YOU HAVE A YSE12, YOUR BOAT IS A 1974 TO 1980 MODEL. CHECK YOUR EXHAUST HOSES. IF THEY ARE HARD OR BRITTLE THEY COULD BE COMING APART INSIDE. IF THIS HAPPENS YOU WILL HAVE RESTRICTED EXHAUST, LOSE OF POWER UNDER LOAD AND SMOKING CONDITIONS. REPLACE HOSES.GOOD LUCK

[Barry]

Thank you to everyone who replied. My problem was a very fouled prop. I went over and scraped the prop and it runs fine now. It's still the clunky one cylinder, but at least it gets me where I want to go Thank you againbarry