Hydrolocked? Yanmar 4JH2-TE

[Geoff54]

Bruce S has the right idea. Here's a few more thoughts.

So now those piston have had a really good soak in PB Blaster, or similar. Right? Give them a extra squirt, just to be sure.

Before you go any further, I suggest getting a block of wood and giving each piston a couple of good whacks. Then try turning the crank again. You might even try an impact wrench if you have access to one. A round block of wood that just fits the bore is ideal, or as close to that as you can get.

If that doesn't work remove the rod caps and see if any piston/rod can be pushed out the top with a few light taps as described by Bruce. . If you are lucky you might find only one piston is really stuck, which will allow you to rotate the crank journal away from that rod. Actually you can do this if two pistons are stuck as long as they are 1 &4, or 2 & 3 but not any other combination. You need to do this because the best way to get a good hit is to do it from the top and, if the there are a couple of rods hard up against the crank, one will stop the other moving. If you are in that situation you may need to pull the crank.

If you free a piston by hitting it down from the top, only move it a short distance, oil it and tap it out from the bottom. All your pistons are near the top of the stroke, so that is the shortest distance. Only remove them from the bottom if you are having a problem getting the rings past a ridge but, if you've cleaned the carbon off of the cylinder wall, I wouldn't expect a problem. The goal is to avoid scoring the bore, or at least to do it as little as possible.

Good Luck!!

[IsaakOker]

Originally Posted by Geoff54

Bruce S has the right idea. Here's a few more thoughts.

So now those piston have had a really good soak in PB Blaster, or similar. Right? Give them a extra squirt, just to be sure.

Before you go any further, I suggest getting a block of wood and giving each piston a couple of good whacks. Then try turning the crank again. You might even try an impact wrench if you have access to one. A round block of wood that just fits the bore is ideal, or as close to that as you can get.

If that doesn't work remove the rod caps and see if any piston/rod can be pushed out the top with a few light taps as described by Bruce. . If you are lucky you might find only one piston is really stuck, which will allow you to rotate the crank journal away from that rod. Actually you can do this if two pistons are stuck as long as they are 1 &4, or 2 & 3 but not any other combination. You need to do this because the best way to get a good hit is to do it from the top and, if the there are a couple of rods hard up against the crank, one will stop the other moving. If you are in that situation you may need to pull the crank.

If you free a piston by hitting it down from the top, only move it a short distance, oil it and tap it out from the bottom. All your pistons are near the top of the stroke, so that is the shortest distance. Only remove them from the bottom if you are having a problem getting the rings past a ridge but, if you've cleaned the carbon off of the cylinder wall, I wouldn't expect a problem. The goal is to avoid scoring the bore, or at least to do it as little as possible.

Good Luck!!

Awesome! Thank you very much.
Once again you nailed the description... Very easy to understand, let's see how easy it's to put it into practice haha

I'll update this thread which is getting rather long tomorrow as soon as I have a first impression of the Piston movement and a few photos

[RLMM]

Too expensive an engine to fool with. Call Yanmar!

[topmast]

Bruce S has it right Remove the cap ends you can get at, tap, tap .soft wood block. If it moves tap piston top back... Forth and back a few times The cap bolts can damage the crank journal so Careful.&The piston ring lands can be damaged The liner and piston are a matched set not borerable and bigger piston and expensive. As a side thought, I once had a drive plate bolt head jam the flywheel in the bell housing .Hard to diagnose without some disassembly. (torque wrench prevention is useful)

[Geoff54]

Originally Posted by topmast

Bruce S has it right Remove the cap ends you can get at, tap, tap .soft wood block. If it moves tap piston top back... Forth and back a few times The cap bolts can damage the crank journal so Careful.&The piston ring lands can be damaged The liner and piston are a matched set not borerable and bigger piston and expensive. As a side thought, I once had a drive plate bolt head jam the flywheel in the bell housing .Hard to diagnose without some disassembly. (torque wrench prevention is useful)

Good advise to be careful not to damage things but I didn't understand "The liner and piston are a matched set not borerable and bigger piston and expensive". Why does Yanmar list an oversize piston if the block cannot be bored? And if shrink fit liners are replaced (I never checked but I'm pretty sure these are shrink fit), the standard machine shop practice is to hone to size after installation to ensure a straight, true and concentric bore.

[a64pilot]

Originally Posted by Geoff54

Whoa, you are getting way ahead of things. I really don't want to get into a stupid internet argument but lets look at these items.

What makes you think that the fuel injection pump needs to be re worked?
Yes, the block might need to be bored but we aren't there yet.
Why shouldn't he lap the valves? There is absolutely nothing magical about diesel valves that means they need some special expert treatment. The seats might need a light cut but lets see what they look like first.
The head almost certainly won't needs facing. Checked, sure , but its a very rigid piece. I severely overheated mine (long story) and it was still dead flat. Cracked a valve guide but the head was fine.
Magnaflux the crank - Really?? And polish it? Apart from the fact that dye crack detection and polishing aren't exactly rocket science, this is a very low stress installation. I'd only do that if I had reason to think that there might be a problem. The bottom end on these engine are super robust. Lets see what the journals look like before we get carried away.
Turbos - why do we think there is turbo problem? And I don't believe it has an intercooler.
Strip the block. Hmmmm. Unlikely that it needs it but we'll have to see. Yes, a complete overhaul might be the ideal way to go but in the real world, it may not be possible or needed.

I have built some very exotic engines and seriously, this is a ******* tractor engine.

I think that the op is doing exactly the right thing - get everything apart and see what we are dealing with. We should be supporting his endeavor and not scaring him with things he probably won't need to deal with. Sure it would be nice if he had some expert help but he's doing ok and several of us are doing the best be can to help.

Cause we will see how this develops, but I’d bet lunch that only a full overhaul will be anything but a patch job.
If I’m overhauling an engine both the injectors and the pump are going to a good Diesel shop to be gone through, and yes there is something magic about a Diesel cylinder head valve wise, it’s the compression, valve sealing is much more critical in a high compression Diesel than a low compression gas motor. You cannot do as good a valve job with a stick and a suction cup as a machine shop can.

Many machine shops want to skim the head and clean it up, I’d avoid letting them do that unless it warped, because skimming a head can cause other issues like valve clearance for example. Do it in a gas motor if you want to, but avoid it in a Diesel and save yourself some grief.
It’s smart to do most of the labor yourself, but a smart mechanic knows what items should go to a specialist as they don’t have the equipment to do the job right.

While you have an engine fully disassembled it’s foolish to not go through everything and reset the clock and make it a “new” engine.
I’m a professional mechanic have been for a long time and if I put my name on it, it’s done right, professional pride is why.
If your not going through the whole thing now, you will later, it’s like replacing the water pump and hoses, you can take the position that they are working now leave them alone, or replace them and get a trouble free decade. Your choice.

It’s like giving the cylinders a light hone to clean out the worst of it, buying .010 oversized rings and filing the end gap to make them work and reusing the original pistons.
Some do that, I won’t, but some do.
If I’m putting all that much work into the thing, It’s not going to be a patch job.

Pay me now or pay me later is true for DIY jobs too.

[Geoff54]

I have neither the time nor the inclination to get into a pissing contest with you.

Originally Posted by a64pilot

If I’m overhauling an engine...

I’m a professional mechanic...

Some do that, I won’t...

If I’m putting all that much work into the thing....

This is the crux of our disagreement. This is not you doing an overhaul, this is someone trying to get their engine running with a small budget. We have no way to know the condition of this engine before he sucked water into the top end ,so let's see what it needs before spending a fortune on a complete overhaul. From what he has said, the cost of a complete overhaul would mean that he just has to walk away. Maybe we can come up with a better outcome.

No one is suggesting that he half-asses anything; only that he inspects and does the work that is needed. We don't even know how many hours are on this engine but given clean oil, they go on for ever. I'll bet lunch that most of this engine specs out ok.

Same with the valves/seats. Mine only needed a light lapping which was a surprise since I replaced the valves and guides but sometimes you get lucky. If this was a competition engine, I'd probably do a 5 angle and then blend (if the rules allowed), but a wider seat dissipates heat better and lasts longer. Horses for courses. Maybe he will need a shop to run some stones or cutters over the seats. Maybe even more. But why speculate until we know? BTW there is a better and easier way to lap valves than using a suction cup but you know that, right?

OK, I'm done critiquing other posts. I'll try to help where I can and then let the op make his own decisions.

Out.

[topmast]

Admit Iv'e never owned a delicate little marine motor like the Yanmar so can only suggest checking with them about availability and price of cylinder/piston. ,over size or not.

[IsaakOker]

So, I've been going for a few hours now closing of any wholes so that no debris can get inside.

I've also tried getting piston 1(closest to the crank) out but I've only managed to get it 1/2inch out of the top.
I'm having a hard time finding the right angle to tap on the connecting rod without damaging anything as it likes swinging to either side.

Any tips?

[Geoff54]

Originally Posted by IsaakOker

So, I've been going for a few hours now closing of any wholes so that no debris can get inside.

I've also tried getting piston 1(closest to the crank) out but I've only managed to get it 1/2inch out of the top.
I'm having a hard time finding the right angle to tap on the connecting rod without damaging anything as it likes swinging to either side.

Any tips?

Have you managed to remove any pistons yet or is this the first? ? Is the crank still in - I assume so? You can wrap the rod with some rags to help hold it in place and help align it with the journal to give you some room to tap down. Sounds like you need to tap it back down a little, clean out any loose corrosion, tap up, and repeat. Now you have a little room, you should probably wrap some tape around the journal to protect it.

[Geoff54]

Are any rings clear of the block yet?

[IsaakOker]

Originally Posted by Geoff54

Have you managed to remove any pistons yet or is this the first? ? Is the crank still in - I assume so? You can wrap the rod with some rags to help hold it in place and help align it with the journal to give you some room to tap down. Sounds like you need to tap it back down a little, clean out any loose corrosion, tap up, and repeat. Now you have a little room, you should probably wrap some tape around the journal to protect it.

OK, I'll give it a try.
Yes, it's the first.. Didn't want to start on the sencond before finishing the first.

I've been tapping it forth and back quite a bit but it doesn't seem to want to come out more than 10.5mm.

Ill keep trying..

[IsaakOker]

Originally Posted by Geoff54

Are any rings clear of the block yet?

Nope, not yet..

[Geoff54]

It's possible that the corrosion wont let the ring push into the groove enough to clear the wear step. You did get all the carbon out of the top of the bore, right. It can be very hard and often needs attacking with emery cloth or wet and dry. remember, round and round, not up and down.

[Geoff54]

Once the first ring is clear you either have to keep going, remove the ring from the piston, or use a ring compressor so that you can go back down,



But the piston is moving.. good sign.