Hydrolocked? Yanmar 4JH2-TE

[IsaakOker]

I'm first going to try to get the pistons out if they want to withought risking too much damage and then have a loot at the bores before taking the crankshaft out.

I'm planning on taking it out but I first would like to see it move(I'm new to engines so to see everything shiny, not cracked, not chipped & moving freely is very pleasing! - you know what I mean haha)

[Wotname]

Curious!

Did the first piston move easily when first tapped or let did it only let go after a few taps (i.e. is it the smoking gun)?

[IsaakOker]

Originally Posted by Geoff54

I just looked it up and those pistons are $320 each. Go easy.

Yep.. I found them for 267$ but still yanmar isn't the cheapest hahaha.

I know that by DIYing there's a higher risk of breaking unnecessary parts but saving money on labour.. Everything has downsides but I'm obviously still careful.. Don't want to have to spend extra, that's why I'm using a light 16oz hammer..

[IsaakOker]

Originally Posted by Wotname

Curious!

Did the first piston move easily when first tapped or let did it only let go after a few taps (i.e. is it the smoking gun)?

Took 7-8taps and from then on 3-4taps - Medium strength- to move it back in and another 3-4 out and so on.. The piston two came out with 3 very light taps.

Piston 3 didn't move at all with 5medium taps so I think this one is for sure the smoking gun if it's only one..

[BruceS]

That first one that only moves a bit then stops ..... is the crank at 90 degrees to the liner and the big end of the conrod hitting the bottom entrance to the liner?
You should remove all the ones that have the conrod hanging pretty straight under the piston first & then see if you can rotate to get the others in similar position. (not familiar with that engine but applies to most)
Top of stroke or bottom. A bit harder to undo the ones at top of stroke but ......

[IsaakOker]

Hii again to everyone!

So big news for me and mystery solved! Piston 1 & 3 were stuck by minimal(my first impression) corrosion on the sleeves.

I have managed to get them all out, my issue was that I wasn't able to tap tight in the center of the rod to apply the force better and more evenly.

Piston 2&4were 2-3minute jobs so very easy.
Suprisingly, piston 4 which had the cleanest bore had 1 ring and the oil Ring veeery loose so not sure what makes them expand but those are the only 2 rings that were visibly loose from them all.

Tomorrow I'll clean them all up, should I scrub them also around the piston and not up an ddown as with the bores?

I have very fine grade #0 steel wool, can this be used to clean a bit more of the rust of the sleeves or is it too aggressive?
And if I were to wet sand it as most people say online, what grit? (I suppose 800 or finer right?)

Once all the cleaning up has been done I'll post pictures into the thread to get your opinions although it's hard to get images to look realistic!

And yes, the crankshaft spins Very easily, I did notice though that if I put my hand on the pulley and move left right real fast, I notice a little play, minimal only though.

🍻

[Wotname]

[BruceS]

I'm not going to advise any further as to what you do.
Very good news it seems?
If it was mine I'd look around for a good backyarder (if you have them in USA?) & see if he can/will assist you in firstly assessing the pistons/rings & then the bores.
With a little luck he'll suggest a good cleanup of everything & he can/will do a cross-hatch hone.
Heck he'll probably even have a couple of broken rings that he can use to clean out the ring grooves!!
There several tools that he'll have that you don't have. Plus his knowledge!!

[Wotname]

Originally Posted by IsaakOker

...... I did notice though that if I put my hand on the pulley and move left right real fast, I notice a little play, minimal only though.

🍻

I know you will get around to reading your own manual after you finish off those beers but here is the gospel re the end play.

[Jim Cate]

I've been following this thread with interest, and I join the others in congratulating you Isaak fpr your persistence and the gurus (Wottie, Geoff, Jim B et al) for their patient and kindly advice. This, IMO, is CF at its finest!

Well done all, and good luck with your further efforts Isaak.

Jim

[Geoff54]

Fabulous! Go grab a beer; You deserve it. Oh, it's late - you probably have already.

A few things. These are just extra things to consider - do use your manual.

Do the bores first. No point in spending time on the pistons until you are sure that you aren't going to have to the block bored. I suspect the cylinders will clean up but.....

I don't think that there is any need to go that fine to clean up the bores - it's ok but a bit slow. 400 is probably just fine. I'd wet it with WD40. A brass brush can help clean out the pits to see how deep they are. Assuming that you can polish out the pitting, or at least only leave a little shallow pitting, you should be ok. You will need to run a flex hone down the bores to get a nice cross hatch for the new rings to bed in on anyway. Flex hones remove very little material but will remove fine pits. The one to use is the 3 1/4" silicon carbide. At someone's recommendation I used 240 grit, which was ok, but the rings took longer than expected to bed in. If I was doing it again, I'd use 320, Although 240 might be better if you are trying to remove some light pitting. Maybe someone else will have an opinion. If you go that route, use honing oil, slowish speed on the drill and keep it moving up and down. I'm sure you'll find a video online somewhere. You can get away with WD 40 or engine oil at a pinch but honing oil works best. After honing clean the bores really thoroughly and clean them again, and again. WD40, then solvent, then clean engine oil, until a white rag or paper towel comes away completely clean. Then do it again. I'm getting ahead of myself but I will have limited time over the next few days.

Yanmar puts a graphite coating on their pistons to prevent skirt scuffing during break-in. On mine the coating was intact - I removed it as I had my pistons coated (ceramic on the crown and teflon on the skirts) but you might want to avoid cleaning it off if you can. It will come off with solvent. Yanmar says not to worry about it on a rebuild but why not retain the insurance if you can. Clean the carbon from the crowns and remove the rings and clean the grooves. The end of a ring and then a brass wire brush is a good way to clean the grooves. Assuming you are going to reuse the pistons, that is. Not critical to go around the pistons because it's the rings against the cylinder that forms the seal, but good practice to go round rather than up and down anyway.

In case I'm not online when you get to it, those $7ish piston ring pliers and some tongue depressors are useful to fit the ring to the piston without scratching things up. Can be helpful to get rings off as well. You can get away without the pliers but trust me on the tongue depressor. And you will need a ring compressor to get the pistons back in. I rarely use a ring compressor but I needed it for this engine.

All right, I'll shut up now. Major progress but you've a way to go. Sometimes it seems like it's taking for ever but one step at a time, eh? Great job so far!

Excuse the stream of consciousness post.

P.S. Although it's fine on the bores, I'm not a big fan of steel wool as it leaves little bits of steel embedded in the surface. Norton synthetic steel wool is much better for that reason.

[BruceS]

Wotname I took it that he was referring to rotational slap .... probably between cam drive gears?

[Wotname]

Originally Posted by BruceS

Wotname I took it that he was referring to rotational slap .... probably between cam drive gears?

Ahh...yes and that is probably because you are better at comprehension that I am .

Re-reading, it does sound like you are right and I am not!

[Icarus]

Originally Posted by IsaakOker

Hii everyone!
I'm new on here so first of all, thank you for having this great community running that I've been reading for years but never had the need to write in.

So my issue as the title states is that I just bought a used sailboat that had been sitting for 5yrs.
It has a Yanmar 4jh2te which I managed to crank but not turn 2 weeks ago while doing a "survey". (Didn't hame any strange noises as if anything was bent inside, etc.)

I went ahead 2 days ago and tried to make it turn over using the battery which is new & the Starter would just "clunk" and not move the crankshaft a single bit so I've de-mounted it and it seems like it's shorting out as it managed to melt the battery poles just by trying to start it once off the engine. (did the same again, clunk but no free spinning).

So I suspect that 2 weeks ago when making the engine turn over it hydrolocked with fresh water(lake) as it never fired up to get rid of the water.
The issue is that I've taken all 4 injectors out & I can't turn the crankshaft so how do I proceed to know if it's really locked before putting a new starter on & risking bending or breaking parts which I might have already.

Thanks to you all!

I read most of the comments regarding a seized engine...in your situation i would suggest to have a mechanic to have a go to free the engine.
Simply because you dont seem to have the technical know how.
Putting light oil into the bores wont hurt...
If it wont budge...id get the head taken off...see what actually causes the lock up...you might be lucky...but since the thing has been sitting for 5 years who knows...
After 5 years without oil circulating the engine might have accumulated some rust...take the rocker cover off, have a look...
As i said...get a mechanic to have a look...

Good luck...

[Wotname]

Originally Posted by Icarus

I read most of the comments regarding a seized engine...in your situation i would suggest to have a mechanic to have a go to free the engine.
Simply because you dont seem to have the technical know how.
Putting light oil into the bores wont hurt...
If it wont budge...id get the head taken off...see what actually causes the lock up...you might be lucky...but since the thing has been sitting for 5 years who knows...
After 5 years without oil circulating the engine might have accumulated some rust...take the rocker cover off, have a look...
As i said...get a mechanic to have a look...

Good luck...

I guess you didn't read post #201. The OP has freed the engine even though he (apparently) doesn't have the knowledge to do so