Stuck with removing flywheel from Yanmar 6LY

twistedtree said:

Did it go BANG when it finally let go?

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Yes, but it was not anything spectacular. Just a medium loud bang like when you snap a 3/8 bolt trying to tighten it or break a 3/4 wrench made of chinesium.
At first I fought I broke something in my setup but than noticed the pulley started to move and at that point I saw fireworks and butterflies all around me and the music band started playing and circus clowns dancing.
This was nice but the bang itself was less loud when I expected.

Waterant said:

Yes, but it was not anything spectacular. Just a medium loud bang like when you snap a 3/8 bolt trying to tighten it or break a 3/4 wrench made of chinesium.
At first I fought I broke something in my setup but than noticed the pulley started to move and at that point I saw fireworks and butterflies all around me and the music band started playing and circus clowns dancing.
This was nice but the bang itself was less loud when I expected.

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Well, at least there were dancing clowns.

If my memory is correct, this whole effort started with a non-running engine that you could not turn over even manually, what was the culprit? My apologizes if my memory has it wrong or I am mixing up different forum threads.

Gdavid said:

If my memory is correct, this whole effort started with a non-running engine that you could not turn over even manually, what was the culprit? My apologizes if my memory has it wrong or I am mixing up different forum threads.

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you are correct. i got the engine out and brought it home.
Currently getting it disassembled for cleaning.

it did not turn because rust was binding the piston's rings to the sleeves and there was some rust on the bearings but it was not too bad, and they cleaned well. a week in evaporust and a nice ultrasonic bath does the trick.

before the engine removal, I did soak all pistons in cylinders for several months in the mystery oil, which did not free them up; also, there was a lot of mud-looking crap in the oil pan and I did change oil which did not remove this crap.

maybe soaking the pistons with ATF/Aceton mixture instead of mystery oil would free them up but i'd probably still have a lot of dirt in the oil pan and blocked oil passages so something would overheat and break shortly causing much more damage.

i wish i did not have to do this but think this rebuild was justified and I'm learning a lot about this engine. hopefully, I'll be able to put it together without too many parts left unclaimed.

Waterant said:

Yes, but it was not anything spectacular. Just a medium loud bang like when you snap a 3/8 bolt trying to tighten it or break a 3/4 wrench made of chinesium.
At first I fought I broke something in my setup but than noticed the pulley started to move and at that point I saw fireworks and butterflies all around me and the music band started playing and circus clowns dancing.
This was nice but the bang itself was less loud when I expected.

Click to expand...

Same thing happened with a brake drum on a friend's old Volvo coupe. They tried all manner of shenanigans before eventually trying my idea of damming up around the interface point of the drum and the spindle with some plumber's putty and allowing penetrating oil to continuously saturate the area. Took a whole weekend of occasional taps of a hammer around the drum to eventually get the oil to work it's way through the cracks. Gave a mild BANG when it released, and then clanged when it fell off onto the garage floor.

Waterant said:

you are correct. i got the engine out and brought it home.
Currently getting it disassembled for cleaning.

it did not turn because rust was binding the piston's rings to the sleeves and there was some rust on the bearings but it was not too bad, and they cleaned well. a week in evaporust and a nice ultrasonic bath does the trick.

before the engine removal, I did soak all pistons in cylinders for several months in the mystery oil, which did not free them up; also, there was a lot of mud-looking crap in the oil pan and I did change oil which did not remove this crap.

maybe soaking the pistons with ATF/Aceton mixture instead of mystery oil would free them up but i'd probably still have a lot of dirt in the oil pan and blocked oil passages so something would overheat and break shortly causing much more damage.

i wish i did not have to do this but think this rebuild was justified and I'm learning a lot about this engine. hopefully, I'll be able to put it together without too many parts left unclaimed.

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Thank you for sharing and I agree that the rebuild seems warranted. If you had freed it up and got it running without a tear down, it probably would have had a shortened lifespan judging by the pictures you have shown. I haven't seen any write ups of DIY rebuilds of these big yanmars but my father has a 6LY in his 390 and while I hope we never need to dig into it this far, I greatly appreciate everything you are sharing along the way.

Gdavid said:

I haven't seen any write ups of DIY rebuilds of these big yanmars but my father has a 6LY in his 390 and while I hope we never need to dig into it this far, I greatly appreciate everything you are sharing along the way.

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I contacted a few rebuild shops for doing this; some of them never got back to me, one told me that rebuilding would cost more than a new engine (and I believe it will with them) and another gave me an estimate of "from $25k" for a rebuild and a few months lead time.
from what i understand, those shops never bother with cleaning and reusing parts like pistons or injectors even if those are in perfect working condition and just buy a new one at retail price (and charge you for it) and Yanmar "marine" engine parts are super expensive

i found some possible replacements from Yanmar industrial engines but it's hard to say if those will fit without buying and trying. Those parts are 5 to 10 times less expensive. I was told Yanmar provided a cross-reference between marine and industrial engines before (i think in the 90s) but now it's a closely guarded secret

So DIY was the only option for me, short of trying to find a rebuilt engine which are not around much. There are used 6LY2A, but they have more HP and some major valve-dropping issue that requires a partial rebuild to fix, and I would probably have to replace both engines and sell the starboard one, so i do not end up with 2 different engines.

plus, what would i do with this seized engine? throw it out? no way, it's too heavy ...
do a crapy fix just to make it rotate and sell as "slightly used"? - way too much work if I can rebuild it properly and put it back. so, here i am.

I'll open another thread or do a blog post with some information and photos on the rebuild.

Waterant said:

I was told Yanmar provided a cross-reference between marine and industrial engines before (i think in the 90s) but now it's a closely guarded secret

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If you come across web links that no longer work, try using the Internet Archive to see if there are cached pages of it from the past. I've used it myself to find older catalog pages and documentation. Lots of vendors consolidated during the post-2008 economic cycle and that brought about lots of discontinued products (and whole product lines). And their current websites often make zero mention of anything no longer available/supported.

Wayback Machine

wkearney99 said:

Wayback Machine

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thanks, Bill.

I'd love to follow the rebuild.