4JH2E teardown report- 8000 hours

[markxengineerin]

I posted this on the PSC facebook group, but thought some here would be interested too, since it's a common engine.

[Jim Cate]

thanks for that excellent report! Goes to show just how durable these engines of ours can be when maintained properly. Should put to rest some of the worries shown in posts here on CF re "old" engines with (gasp) 2000 hours run time, etc.

Well done! And a follow up would be nice...

Jim

[BoondocksHawks]

Very cool report and good perspective - thanks for posting!

[Tetepare]

That’s a great review. Thanks

[Timreyn]

Nice report. I run many natural gas engines, which are converted diesels, Caterpillar etc. They will run a long long time with little wear. But a head job with new seats and valves is money well spent. We usually do these two or three times as often as overhauling an engine. Ring grooves wear out but sounds like you have this covered. This is what I would expect to see when I get to your hours. I have about 2300 now. Thanks for the info!

[Kinchega]

Excellent and informative report, thankyou
Man I am retired and wouldn't have the time to create a report like that��

[Recy]

I couldn´t find the FB PSC group. What is it?

[Lowcountry]

I have a 1988 4JH2E with 2050 hours on it in my HC33. That engine runs like a top! Very pleased with it, and delighted to see the results of your teardown at 8000 hours. Here's to well-maintained Yanmars...

[Sail2there]

Very usable report! As a former engine mechanic this blows away my method of a notepad with handwritten chicken scratch


Thanks for identifying what oil you use as well. There's always a lot of discussion regarding oil and oil filter brand, so when someone takes the time to produce visible results such as this, it's a great reference!


Your plan of hone, rings, lapping & seals seems appropriate. Looking forward to your findings on why the hi temps



I hope you back er' back together on one the water soon

[flightlead404]

Very nicely done thanks for sharing. I’ve been inside numerous oil cooled gasoline engines but never a diesel. Interesting.

[jack630]

Thanks for the report.

Who did the work?

[markxengineerin]

I couldn´t find the FB PSC group. What is it?

Facebook Pacific Seacraft group. Only reason I finally joined facebook.

Man I am retired and wouldn't have the time to create a report like that

Ha, I do these type of things for work all the time so I've gotten efficient, probably took 1 hour

Who did the work?

Me

I run many natural gas engines..

Thanks for the info. I dropped the head off at the local machine shop today, they have better equipment than I do to grind valve seats. I will have another update in 2 weeks.

[aqfishing]

Thank you for a great report.

On our commercial fishing vessels 35000 hours would be a bare minimum!

I have 2 questions:

What sort of hours would you expect to get from a 29hp Yanmar?

I see you change your oil every 100-150 hours, we change our commercial engines every 250 hours, and even then the oil we have tested has not broken down. What is the recommendation from Yanmar on this?

[Dogscout]

Thankyou for the great report. I have to ask regarding the main and rod bearings. Have you tried Plasticgauge? to determine wear?

[markxengineerin]

What sort of hours would you expect to get from a 29hp Yanmar?

I'm not sure, I have no other yanmar experience besides what you're looking at, so my guess would be "similar" or 8 to 16,000 hours depending on your tolerance for leaking valve seats.

we change our commercial engines every 250 hours

I am going to test the oil a few times and target this number, moving forward. I don't know about Yanmar, couldn't find the number from them specifically, but Pacific Seacraft owner's manual says 100 hours. I assume they got that from Yanmar.

Main and rod bearings have a very thin (microns) coating of tin, lead, lead-tin, something like that. It's only worn through on the rearmost main bearing, so I'm sure the clearances are fine. I will move the shells around just because I can, but these have another 8,000 in them as long as the driveshaft alignment is good. Some would say "replace them, they're cheap", but there's so little wear, I don't justify it : )