Lifespan of Yanmar 40hp 3JH3

[LLizzard]

I've recently looked at a cat with over 8,000 hrs on 40hp Yanmar 3JH3 engines. What's the expected service life of such engines? Would one expect that they'd need to be rebuilt/ replaced relatively soon even if service has been meticulous?
What would one expect to be the cost to rebuild such engines, if they are even rebuildable? Cost for new Yanmars or other replacements?
Thanks

[Thank you dad]

Originally Posted by LLizzard

I've recently looked at a cat with over 8,000 hrs on 40hp Yanmar 3JH3 engines. What's the expected service life of such engines? Would one expect that they'd need to be rebuilt/ replaced relatively soon even if service has been meticulous?
What would one expect to be the cost to rebuild such engines, if they are even rebuildable? Cost for new Yanmars or other replacements?
Thanks

I can tell you since i bought 1 today, a new 3YM30 is around 13 list price and depending on your dealer, you should be able to get it around 10-10.5.

You would be looking at 1 size up so maybe another grand or 2 for the next size up.

[donradcliffe]

The engines are nearing the end of their expected service life. As a buyer, you could expect to replace them for about $30k (someone else doing the work), or get them rebuilt for about half that much.

[Navicula]

If it runs fine you may get another 10,000 hours out of it.... why replace anything that's not giving you a problem

[a64pilot]

I'd say that at those kind of hours they are run out.
I'd make my offer expecting to have them replaced, I'd think the seller is expecting that.

[daletournier]

Originally Posted by a64pilot

I'd say that at those kind of hours they are run out.
I'd make my offer expecting to have them replaced, I'd think the seller is expecting that.

I agree with this, I would be negotiating price with engine replacement in mind BUT I most likely wouldn't replace them until I had to.
I've seen yanmars with 10,000 hrs on them. A mate has one with 14,500 hrs, he charges the batteries twice a day and never runs it hard. Hes made me question what I thought I knew regarding how to treat my diesel.

Sent from my vivo Y35 using Cruisers Sailing Forum mobile app

[kmacdonald]

If they are not burning oil they may still have some life left in them. I wouldn't preemptively replace them. I think some of the harbor launches use that engine and they get about 10K hours before rebuild.

[UNCIVILIZED]

What's the engine oil analysis say?

[StuM]

Originally Posted by UNCIVILIZED

What's the engine oil analysis say?

And the compression test?

[fjwiley1]

Do As suggested by "UNCIVILIZED" and "StuM".
Nuff said...

[Matsubob]

An engine's life expectancy is affected by so many variables that it is difficult to say what kind of condition it is in based on just the number of hours. It is definitely a high hour engine, but it depends on whether maintenance schedules have been followed, what kind of environment it has "lived in" (such as "dirty, wet, not well ventilated, causing moisture buildup/rust")
If the engine is in good shape, it is not that hard a job to do a "freshen up" on it. Pull the head, lap the valves and check the stems for wear, then install new valve seals, then drop the pan, pop the pistons out, and if the crank shows little or no wear, replacing rod inserts on the bottom end will be sufficient. The piston pin bushings should be replaced; have a machine shop ream each one to exactly fit each piston pin, then check the cylinder walls for scoring or pitting. If they are OK, check each one for wear by measuring the ring gap using the top compression ring from each piston in its respective cylinder. If thecylinder measures out to be within specs, simply replace the rings (new ones) and come back up with it.
Yanmar parts are expensive. But if you do the labor yourself, you can get by for around $2,000.00, and you and your engine will be HAPPY!

[Matsubob]

That figure that I threw out there just now was PER engine, of course. And of course, that is assuming that nothing major has to be done, due to catastrophic occurrences in the engine.

[Rick Williams]

I just had my 54 HP 4JH rebuilt for $8,000.00. that included out and back in to the boat, new pistons, rings and rods, valves and heat exchanger. I got to see what happened when the PO tried starting the engine with #1 full of water.

[LLizzard]

Thanks all for the replies. I know that with all the variables, you never know how long engines will last. Just wanted to confirm my thoughts that they were "long in the tooth" and take that into consideration if I decide to make an offer.
Re oil analysis and compression check, yes I would do that as part of an engine survey once an offer is accepted. However I was taught that for an oil analysis to be truly telling, you need a previous analysis from that engine for a comparative analysis. That is rarely available, so you do an oil test and compare against "normal" wear for an engine of that hr range.
Thanks again,
jeff

[shawndear]

Originally Posted by LLizzard

I've recently looked at a cat with over 8,000 hrs on 40hp Yanmar 3JH3 engines. What's the expected service life of such engines? Would one expect that they'd need to be rebuilt/ replaced relatively soon even if service has been meticulous?
What would one expect to be the cost to rebuild such engines, if they are even rebuildable? Cost for new Yanmars or other replacements?
Thanks

I have a 3jh4 that had 10,800 when I bought the catamaran 6 years ago and was told by the surveyor that I should consider replacing it. I have done nothing but oil and filter changes since then and it now has 15,200hrs and still sounds good and operates well - but just doesn't look pretty.