Yanmar 4LHDTE

[parnold1]

I have a 1999 170hp Yanmar turbo diesel in a 25ft lobster boat. It has 190hrs, regular maintenance etc. Coolant, oil, filters all ok. The boat may sit on a trailer for several months without use. In May, when first throttling up under load, the engine would only rev to 1700rpm and smoked like heck at that point. After repeating this exercise for a number of times it would rev right up to the 3200rpm red line if I wish. Had to run the engine up and down for a half hour last week before it would run right. When it runs it's just fine.

 

[Joe G.]

Do you put a biocide in your diesel before parking it? Could be algae build up.

 

[LarryB]

I agree with Joe. Definitely sounds like a fuel quality ptoblem.

 

[parnold1]

I always usew biocide, I've cleaned the tank out (which had absolutely no residue), put in new filters. I had several boats pack up filters at the worst possible moment till I learned the hard way not to compromise on fuel cleanliness. I wonder if the turbocharger shaft could be"hanging Up" enough to prevent it from spooling up to pressure till it works itself loose from repeated tries and from heat. I guess I should put a pressure guage on like I put in my CTD.

 

[Motorhead]

CHASING a GREMLIN

Checking the boost pressure is a good thought but I wouldn't think that it would smoke heavily without boost enriching the pump. How is the inj pump enriched? Does it take meerely boost to enrich like the VE bosch(1st gen pumps) or is it like the p7100? I would be careful that you are not getting oil dilution when it is smoking heavily. Try some Stanadyne or other good pump lubricant aditive... maybe something is sticking. I don't know the accessability of the engine but could you ck the turbo rotation before you fire it for the first time? Chris

 

[dpetre]

Marine diesel

I had a problems with one of my marine cummins engines not coming up to full power. It would take forever to get on plane and then the problem would go away. I change fuel filters and drained the fuel tanks and nothing seemed to work. I finally took the fuel lines and shut off valves apart and found that small pieces of aluminum where plugging the lines and valves. The tanks where put in two years ago and where not cleaned of the welding fragments. Once I cleaned the lines everything works great.

 

[parnold1]

Thanks for the replies re: use of additive and fuel line debris. I haven't used that type of lubricant additive but I will. The manual is pretty meager but there is a reference that shows pouring distilled water into a plug hole in the turbo to clean it, can't remember which side. It must be with the engine off - I could see getting water in my face otherwise. The problem is intermittent and related to sitting up a while. After it began to not power up, I used the boat 75 hours on a near daily basis in the Bahamas without a hiccup. I can get to the engine well enough to get in that plug hole and try to gently spin the turbo, I'll also check the lines, again, thanks for your ideas.

 

[Motorhead]

It sounds like they want you to pour water on the exaust side to clear out salt water. The engine must have a wet exaust. Prehaps condensation is building up in the exaust side of the Turbo and causing it to hang up. Do you idle down for a time before shutting down? This would cool down the wet exaust and keep the condensation down to a minium. Is the boat pulled out of the water each time after the season of use? If so you could do a short dry blow out of the wet manafold. Does the engine cool directly with sea water or have a salt/fresh cooling transfer system. Lastly, The time to ck the stuck Turbo theory would be before starting it for the first time at the beginning of the season. Remove the intake boot off of the compressor side of the turbo and GENTLY see if you can turn the compressor shaft. If so then the problem must be somewhere else. Chris

 

[parnold1]

Chris, The engine has a wet exhaust, is fresh water cooled, and has a heat exchanger for the block, intercooler, and oil cooler. I do idle down to cool the turbine before shutoff, usually 5 min or so if I can. The boat is used for a day usually, sometimes more, and is pulled out after. Condensation is probably a factor for all the internals, although the boat sits under cover on a trailer, the temperature and humidity variations in N. Florida promote condensation. I have a way to hook up to the hose at the raw water intake if I wished to run the engine while on the trailer. The engine sucks so much water that it sometimes collapses the hose and so I only do this to rinse after salt water use and not otherwise during layup periods. I will pull off the hose to the intake and take a peep at the turbine, actually I think there is a 4 or 5 inch hose on the exhaust side too.