Yanmar Lack of Power

[casual]

Hi everyone,I am purchasing a used new boat to me.The boat has been on the hard for 2 months due to teh Hurth trans failing.The boat has a 55hp year 2000 engin with 1600 to 2000 hrs reported.The trans was reinstalled after rebuild the engin started.The tecnician reported the engin would only rev to 1500 RPM's.Prior to the trans failing all was suppose to be good with RPM's.Am told filters are clean and fuel supply looked goog whatevere that means.This boat has only been started on the hard after trans rebuild.Anybody and everybody please respond,Thank you kindly

[Cheechako]

Well.... if all the "rumors" you've heard about being OK prior to Trans rebuild... then it sounds like you have a transmission problem. On the other hand, if you dont know for a fact that everything was kosher prior.... I would take any statements with a grain of salt for sure. I've had people selling boats tell me the boat has a new engine, but when I ask if they have the receipts they say things like: "that's what the previous owner said". If I understand you correctly, the boat is on the hard. Not sure I would want to rev a diesel up to max with no load. Sure it isnt just a throttle cable issue from the trans removal etc? If none of the above, it sounds like a fuel issue.... although I would expect it to vary rpm on it's own if it's fuel.

[Charlie]

My guess it is a JH engine. I would think that you have a problem somewhere in the fuel or injection system but I don't know enough to give an accurate guess.

[Tellie]

Is that 1500rpms in gear or out of gear?

[delmarrey]

Originally Posted by Tellie

Is that 1500rpms in gear or out of gear?

If the tranny get hot while on the hard, I'd suspect the tranny. The clutchs/cones may be dragging.

BTW Yanmar recommends full throttle periodically.

Originally Posted by Yanmar

If possible, periodically operate the
engine at near maximum rpm, while
underway.
This will generate higher exhaust
temperatures, which will help clean out
hard carbon deposits, maintaining
engine performance and prolonging the
life of the engine. NOTICE: NEVER
turn off the battery switch (if
equipped) or short the battery
cables during operation. Damage to
the electric system will result.

Originally Posted by Yanmar

Normal Shutdown
1. Reduce engine speed to low idle and
put remote control handle in
NEUTRAL.
2. Accelerate from low speed to high
speed and repeat five times. This will
clean out the carbon from the cylinders
and the fuel injection nozzles.
3. Allow engine to run at low speed
(approximately 1000 rpm) without load
for 5 minutes. CAUTION! For
maximum engine life, Yanmar
recommends that when shutting the
engine down, you allow the engine
to idle, without load, for 5 minutes.
This will allow the engine
components that operate at high
temperatures, such as the
turbocharger (if equipped) and
exhaust system, to cool slightly
before the engine itself is shut
down

[casual]

Thank you all,I have to travel 1500 miles to inspect,and sea trial,taking all opinions with me fuel sounds like no1 never thought about the trans getting hot maybe new trans too,Does this Yanmar have inherant problems?I have been reading the post and see plenty of Yamaha sitituations.In my current boat I installed a universal M$ 30 20 yrs ago,not one problem since.I am leary already,If someone could point me as what to look out for I would be appreciative,I have 1500 miles to come home and at least 400 off shore.Thanks again Casual

[Tellie]

You're not really giving enough info. Is the boat on the hard while testing? Is the tranny getting hot while the engine is supposed to be out of gear? Are you blowing alot of black smoke when trying to accelerate past 1500? Give a more complete description on what you are doing. There are a lot of reasons why any diesel engine won't go past 1500rpm. I'd be asking your tech for a more detailed explanation on what he is doing.

[Jon4399]

I was speaking with the Yanmar dealer earlier this week. He mentioned that he has seen several cases of the exhaust manifold getting clogged, resulting is the engine not being abe to rev to its rated rpm. Suggest a sea trial and after warming it properly, run it at max throttle and see what the max rpm is. There are also some posts here about corrosion between the manifold and elbow.

[Tellie]

Originally Posted by delmarrey

If the tranny get hot while on the hard, I'd suspect the tranny. The clutchs/cones may be dragging.

BTW Yanmar recommends full throttle periodically.

Yeah as a rule, go back to the last thing you fixed. But this engine has a few hours on it it could be a handful of things related or not related to the tranny. He's not given near enough information yet. I agree with Yanmars recommendation but very very few captains adhere to anything like the above procedure. There are tons of threads on CF where it is near impossible to convince owners that running their diesel engine hard is good for them. Fuel consumption becomes far more important than any possible damage they may be causing. Ask any diesel mecahnic if he's ever heard the term "Killed it with kindness" How many posters here would admit they never run their diesels in idle for five minutes before shutdown. How many would admit they don't even know why it's recommended. Diesels take a bad rap far more than is deserved and get blamed far more for being at fault than where many times the blame really belongs, with the owner. A owner that just does not understand many of the simple basic principals of their diesel or the rest of their boats systems for that matter. I'm not picking on the OP but I see this all the time at the working docks and yards. People, subscribe to Latts and Atts, take a few ASA courses, then drop a few hundred grand on a boat and shove off for adventure and Rum Runners only to find themselves right back at the dock a week or two later complaining how expensive repairs are. OK it's late and I'm drifting off on another rant, sorry.

[DeepFrz]

If the engine doesn't run properly on inspection, it needs a new engine. Same goes for the transmission as they may have slapped something together to make it look whole. Anything on the boat that the owner or his agent can't demonstrate properly to you doesn't work and needs replacement. That is the only attitude to take when buying a boat. You are going to hire a surveyor aren't you? And take it for a shakedown cruise? And get an engine survey done? If you don't do these things they will bite you hard.

[casual]

I,am tending to aggre .Trans was just overhauled out of boat when I made deal.100% sure saw pictures from surveyor.A Yanmar with 1600 hours should not be at the end of its life.Price is good boat otherwise is solid,decission's decission's.

[Cheechako]

I just read a Q and A that Nigel Clader answered yesterday with an engine with this same problem. Turned out to be fuel/algae collected on inlet /out areas of fuel filters. A new filter would cure it for an hour or so and then it started not getting above 1500 rpm again. Unless it's smoking alot or knocking I wouldnt assume the engine is bad.

[casual]

Thanks Will look in to that also.Seems contrary that a boat that ran fine 2 months ago would develope this condition ,perhaps the owner never ran the engin up and it goes hull speed at 1500 rps.Just guessing

[delmarrey]

A 55 hp motor should do 3000 rpm's. With your experience, do don't want to buy a boat that you can't take out for a sea trial.

[casual]

Staying home this weekend,let the PRO's do there thing ,after that I'll hire my own pro to check the PRO PRO's.All of you folk's have been a Great Help.Many Thank's