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Recently bought a 1983 Hunter 34. Awesome boat. Sail here in Holland MI, went out for the first time last Saturday, It was freezing. The Yanmar Diesel ran fine but it does have the most hours i have ever seen on any engine. It has 1,380 hours. The surveyor said that these engines are pretty bullet proof. At what point is it time to have it rebuilt? It smokes a lot at high RPM's but otherwise starts right up and runs fine. The previous owner was meticulous about the boat so i am confident it was maintained. Any suggestions or advice or maintenance tips about this engine would be great. It is the 20 horse model.
 

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ancient mariner
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NoDestination-----by hi RPMs , what rpm do you mean? is this a yanmar 2GM20 ? what color is the smoke ? if it is black, it could be caused by a dirty air cleaner, bad injectors, or a prop with too much pitch, causing overloading of the engine. how high is the engine RPM at no load compared to full throttle in gear?
 

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lots of life left

only 1800 hours! That's nothing for a Yanmar 3GM. My old H34 didn't even have an engine hour meter and the Yanmar ran like a sewing machine. Just keep the oil changes frequent, replace/clean-out the mixing elbow, and check the raw water pump. She's a great little engine.

I've inheritied twin 3gm30f's that have been totally abused on an ex-charter cat. The enging hour meeters long stopped working, but I'm guessing well over 5000 hours each. They have thier moments but are still running. I'm looking at repowering and will put rebuilt 3gm30f's right back in thier place!

You've got a great engine in a great boat. Congrats.
 

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Telstar 28
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Umm... you must not look at a lot of engines... I've seen some with over 8,000 hours on them... If the Yanmar smokes at high RPMs, something is wrong with it.

Given its age and the number of hours, my guess is that it wasn't used much, or maintained properly. If the owner had been going by the number of engine hours for his maintenance schedule, chances are that the engine did get its oil changed much more than every two years. 1380 / 26 =53.08 hours per year or so...

Chances are also likely that it wasn't run very often long enough to blow the carbon/soot out of the engine or to heat off the moisture that collects inside an engine.

I'd rather have an engine was used regularly and well-maintained than one that was barely used and maintained on a minimal schedule—which is what this one sounds like.
 

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I have a 1979 2GM15, with many more hours, runs great. 1380 hours is nothing for a diesel. Maintain it well and it has many years left. FYI, I add about 60-80 hours a year which is just above your average annual running time.
By the way I spent my freshman year at Hope College in Holland. You are indeed brave to be sailing already. Has the lake ice even cleared? Remember the Titanic!
 

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Discussion Starter #7
Thanks for all the replies thus far. The smoke is black not blue so it is not burning oil. It is revving at about 4,000 RPMs full tilt in gear i believe. Like i said it was the first time out and it was freezing. Next voyage i can answer more of these questions. What is the mixing elbow? and how do i clean it?

Thanks
 

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Ya it was awesome. We spent the night out there at El Deans it got about 25 degrees. Check out our website three3degrees.web.com. Co owner still goes to hope.
 

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Smoke can have a variety of causes. It's often the result of a dirty prop and bottom. Another common cause is a prop with too much pitch. If you run up against your hull speed and try to power faster, you will get smoke. As mentioned above a clogged mixing elbow can be the cause. Buy the Yanmar parts and service manual for the engine and follow the service intervals, including the elbow and injectors. If there is no records on board of servicing these items it's time to do it. Pulling the injectors and sending them off to be rebuilt is not a difficult job. I would spend this season getting know the boat and engine, then pull the injectors next fall. If you can get to the elbow it's not hard to remove, inspect, replace it if needed. Do be careful on the re-install as you are working with a system that handles carbon monoxide! I use some exhaust system sealer between the elbow and block.
 

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Find out what model Yanmar you have, (ie 2GM,2GMF, 2GM20, #GM, etc), then someone here can tell you what the max recommended rpm is, and what the max continuous rated rpm is. Off the top of my head 4000 seems a bit high - my 1982 2GM has a max of 3600.

What speed were you going when it smoked? You likely were near / at hull speed and will not go faster, even if you had a bigger engine!! I think you were pushing the engine a bit too far, and trying to get more speed than it will do continuously.

Engine should be good for years to come. Great that its starts easily!!

As others have said, get a manual, or download one - get familiar with the engine for troubleshootingm, fuel filter changes (and necessary priming), etc.
 

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AHOY!
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What is the mixing elbow? and how do i clean it?
it is an evil and devious part of the exhaust/cooling system that tricked me in to spending 1000s of dollars replacing just about every other part of the engine. Then one day I went to the boat with a flathead screwdriver, used it to remove the hose clamp, and then janmmed said device in to the elbow. Some carbon fell out, put hose and clamp back on... Engine fired up first shot.

I later talked to Yanmar and the do recommend inspect/replace every 3 years (dont quote me on the interval)

good luck with the new boat!
 

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I believe Yanmar recommends replacing the exhaust elbow every 500 hrs. though it is probably not necessary ( just a good cleaning) but I do carry a spare.
3GMD/ 22 hp. and 25 yrs. old still purring!
Bill,
 
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