Yanmar Lifespan?

I am contemplating a power cat that has twin Yanmar 4JHE-TE engines ... 75 hp and turbo. They currently have about 4400 hours each, but have been meticulously maintained by the owner, who is ex-navy and quite obsessive. What is a reasonable life expectancy of these engines? Any thoughts, comments, and experiences would be appreciated.

David

I can't speak to that particular engine but I have seen the non turbo version with 9000 hours that ran well. Of course so much depends on maintenance, use, propeller pitch, etc. It might be interesting to see an oil analysis history exists...
Bruce

Find out if coolant has been replaced on schedule, what coolant was used, and last time the heat exchangers have been cleaned.

If truly well maintained, 4400hrs does not freak me out.

How's the access to the engines all around? Some cat's are nightmares, some are pretty good.

Still subject to them being surveyed. Ex Navy obsessive means nothing until the condition of the engines reflect it. I knew an ex navy submarine mechanic who didn't believe in ever changing the oil in his car.

Just saying not to let the apparent history make you skip an important step.

BandB said:

Still subject to them being surveyed. Ex Navy obsessive means nothing until the condition of the engines reflect it. I knew an ex navy submarine mechanic who didn't believe in ever changing the oil in his car.

Just saying not to let the apparent history make you skip an important step.

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You can get away with that on a Detroit, just change the filters and keep it topped off, it will drain the old stuff on it's own.

Gdavid said:

You can get away with that on a Detroit, just change the filters and keep it topped off, it will drain the old stuff on it's own.

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I'm just saying that many times Navy or whatever, the story is how well things have been maintained and the current condition doesn't support that story. Sometimes I've seen it be a lot of maintenance by someone who didn't know what they were doing. Some of the worst messes I've heard of have been due to improvements and changes made by very diligent owners.

The JH 55hp has a bullet proof rep but I don't know if it extends to the turbo or turbos. I think there are several versions of turbos on that engine and one may be almost like no turbo at all. But I don't think turbos are the least bit bad as long as the boat is propped correctly.

We had a 3cyl Yanmar and it was great. Except a slight corrosion issue that led to the purchase of my specific engine on my present boat .... Whereas there is no aluminum on that engine. With the exception of the valve cover.

But re the OP there's no bad new engine .... only engines that haven't been maintained or operated responsibly. But Yanmar engines are fine in my book.

My neighbor had one on his sailboat and I helped him with an overheating problem, so I am somewhat familiar with it. The 4JH is a 2 liter engine and at 75 hp you aren't stressing it badly. OTOH I am sure that it doesn't have the tricks of its higher powered cousins like piston lube oil spray, etc.


Like Ski I am not freaked out by those hours if it was maintained well and run right. Check the phototached wot rpm. That says a lot about an owners attention to the engine.


And I agree that ex-Navy means little. I have seen kids run small assault water craft one of two ways: full out or stopped. The Navy has its 1,000 endurance test where the engine is mostly run flat out for a reason.


David

djmarchand said:

And I agree that ex-Navy means little. I have seen kids run small assault water craft one of two ways: full out or stopped. The Navy has its 1,000 endurance test where the engine is mostly run flat out for a reason.


David

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You have auto mechanics who completely ignore maintenance on their own car. I knew one who had to short wire it every day to start it until his boss told him to step outside and fix it now, that it was embarrassing for customers to see one of his mechanics doing that.

"The Navy has its 1,000 endurance test where the engine is mostly run flat out for a reason."

The Navy usually specks heavy duty or industrial engines so can perform this sort of test.

For auto or lawn implement sourced engines , a different duty cycle is expected.

I just dropped off my 4JH-TE (55 HP Turbo) at a local dealer for servicing before it goes in the boat we're building. It has 675 hrs on the clock (came out of a racing yacht). The head mechanic told me they have the same engine in their work barge and it's got 15,000 hrs on it, never rebuilt but properly maintained.

The upside is it made 4400 hours, would not have gotten that far if not properly maintained. Good engine survey with oil analysis should tell you the full picture.