Hydrolocked? Yanmar 4JH2-TE

[CassidyNZ]

All the talk about boring the block - the 4JH family of engines have loose liners and cannot be bored. A light hone will determine salvaging the current status but if the OP is on a tight budget, the barrels don’t have to be flawlessly perfect. If the bores are shagged, liner kits are the only (bloody costly) solution.

If the barrels can be saved and the piston survived the bashing to get them out, the grooves need to be cleaned properly until the inner face of the groove is visibly aluminium. If this is not done properly, the new rings will not fit. Best tool for this is a pice if the old ring.

Then the best ring from each groove should be used to check that the grooves have not been widened by the bashing during removal (lands distorted). The ring should be goodish fit with the ability to Rick up and down a whole lot. If the rings wobble side to side too much they fidget the liners while running and problems will soon ensue. How much should they wobble? Sorry can’t advise that, it’s an experience thing.

To check the valves with minimum effort, lie the head in the workbench with the ports facing up, fill the port with kerosene or gasoline. If the liquid leaks past the valve remove the spring and valve stem seal and lap the valves in. If no leaks, the valves are good to go.

It’s a real shame the OP isn’t in New Zealand. I can source a 4JH4-TE right now with just 3500 hrs and no problems for just $3.5k

[Wotname]

Originally Posted by CassidyNZ

........


Then the best ring from each groove should be used to check that the grooves have not been widened by the bashing during removal (lands distorted). The ring should be goodish fit with the ability to Rick up and down a whole lot. If the rings wobble side to side too much they fidget the liners while running and problems will soon ensue. How much should they wobble? Sorry can’t advise that, it’s an experience thing.
............

And when experience is lacking, one can always fall back to the Yanmar 4JH2 manual

[IsaakOker]

Good morning to everyone!

Thanks for the tips on how to move forward!
I'm going to get some gauges as I have a vernier already. I will then measure everything and determine what's good and what not.
In the meanwhile I'll take the exhaust manifold apart to clean and inspect, same for the elbow & the intake manifold.

How would you or even better, would not clean these? Specially because many advise againt a quick 5 minute acid solution flush for the head exchanger.

I've also had a mechanic come by and have a look at the engine.
He says he can't believe how lucky I am as he also saw the engine when it was seized.
He said that the "score" in one of the cylinders isn't an issue because it can't be felt by hand and you can still see the cross over it.
As for the pitting, he believes that with a fine ball hone it can be redone, if that isn't enough then a stone hone but he would go that fast yet as it's not too much pitting if all the dimensions & measurements are fine.

The only thing he did point out is that I should test the valves for leaks as they seem very good but you never know & he would remove the camshaft to give it a good clean as there's one spot with some rust, hard to access.

I'll keep updating the thread so that everyone can see what the outcome is in the end.

I'm going step by step so first I'll clean my components and will give the block a good clean too so that I have a clean start.

[CassidyNZ]

Originally Posted by IsaakOker

How would you or even better, would not clean these? Specially because many advise againt a quick 5 minute acid solution flush for the head exchanger.

One doesn’t have to use a heavily aggressive acid but a good wash with something light (rust inhibitor, for example) would be good. The more important question, given that you had rust inside the engine, is whether or not the exhaust header (heat exchanger) has a hole/leak that is allowing raw (salt) water into the cylinders. This is quite a common failure on a lot of marine engines but to be honest, I can’t recall ever seeing a Yanmar header rust through.

Still, it’s worth a pressure test, even a crude one with a garden hose (budget in mind). Also, check the mixing elbow.

[Geoff54]

Originally Posted by CassidyNZ

All the talk about boring the block - the 4JH family of engines have loose liners and cannot be bored.

This is the second time this has been claimed. Can we resolve this? Where did this come from?

I thought it might come from the fact that 4JH and 4JH2 are based on the 1.6 liter block and later models are based on the 2.0 liter block. But directly from the 4JH3 manual.

"If a cylinder suffers eccentric wear or flaw, perform the honing or boring"

"For great eccentric wear, however, the honing must be performed after the boring"

Also Yanmar list oversized piston but not replacement liners.

So, why do people think this??

[a64pilot]

I think that there are apparently some 4JH engines that are wet sleeve.
I thought my 4JHE was until I started doing a little research cause I had seen where apparently a 4JH engine was.
I liked that as I love wet sleeve engines, that means of course that I can return an engine to factory new spec, but then found out that mine is dry sleeved.
I wish it was wet sleeved though.

It’s so common a misconception, leading me to believe that maybe some are.

[Geoff54]

Originally Posted by IsaakOker

How would you or even better, would not clean these? Specially because many advise againt a quick 5 minute acid solution flush for the head exchanger.

For the heat exchanger, remove the end caps, see what it looks like and then ask again if you need to. Mine was surprisingly clean. New 'o' rings with a little silicon grease when you reinstall.

On other things, a light coating of carbon is normal otherwise scrape, wire brush, emery paper. Some copper brushes in a drill or rotary tool can help sometimes without removing material you don't want to. If you need a solvent to remove gummy deposits, WD40 is good and electrical contact cleaner is safer that most other solvents. Avoid brake cleaner, it's nasty stuff and never use it on a hot surace.

Common sense and be judicious with chemicals and I'm sure you'll be fine.

Good new about the cylinder. Fingers crossed.

[malbert73]

Originally Posted by a64pilot

I think that there are apparently some 4JH engines that are wet sleeve.
I thought my 4JHE was until I started doing a little research cause I had seen where apparently a 4JH engine was.
I liked that as I love wet sleeve engines, that means of course that I can return an engine to factory new spec, but then found out that mine is dry sleeved.
I wish it was wet sleeved though.

It’s so common a misconception, leading me to believe that maybe some are.

My mechanic told me before I repowered that my 4jhe could have liners easily replaced. What’s wet vs dry sleeve mean?

[CassidyNZ]

Originally Posted by Geoff54

This is the second time this has been claimed. Can we resolve this? Where did this come from?

Attached image taken directly from my genuine, original Yanmar-issued 4JH engine manual.

I'm guessing others have different views, I guess its up to them to post.

The next page of the manual goes on to explain liner heights, etc.

[a64pilot]

Originally Posted by malbert73

My mechanic told me before I repowered that my 4jhe could have liners easily replaced. What’s wet vs dry sleeve mean?

Wet vs dry is likely what us redneck mechanics call them.
A wet liner is just that, it’s installed directly into the water jacket with O-rings at the bottom to keep the water and oil from mixing, and a metal to metal seal on top.
I could pull them out of a John Deere backhoe by putting my hand into the liner and making a fist and just pulling them out. That way you could completely renew the engine bore without a machine shop.
Also as the liner is perfectly round and exactly the same thickness so as the engine ran the liners shape and size due to heating was more even.

A dry liner is pressed into the engine block that is bored out, its not in the water jacket. There is cast block between the two.
It can be replaced by a machine shop, but is often considered to be not as good as new as the press fit may not be as precise and the transfer of heat not as good, many believe that a replaced dry sleeve runs hotter than a factory installed one.
No back yard mechanic can replace a dry sleeve.

Wet sleeves enable what is called an inframe overhaul, a Backhoe or Farm tractor for example the engine is often the front half of the machine, to pull an engine is difficult as the tractor has to be spilt in half, but with wet cylinders you can accomplish a pretty good overhaul by just removing the oil pan and cylinder head.

[LeaseOnLife]

Originally Posted by CassidyNZ

Attached image taken directly from my genuine, original Yanmar-issued 4JH engine manual.

I'm guessing others have different views, I guess its up to them to post.

The next page of the manual goes on to explain liner heights, etc.

The OP has a 4JH2 not the older 4JH. 4JH2s do not have liners. I had to bore mine during rebuild.

[Geoff54]

So it looks like only 4JH have replaceable liners. Or as A64 says his 4JH has dry liners, maybe just early 4JHs. I was actually under the impression that 4JH and 4JH2 used the same block, but maybe not. Anyway, mystery solved. 4JH series are have dry, borable, not easily replaced liners, except for the early ones.

[Wotname]

Originally Posted by Geoff54

So it looks like only 4JH have replaceable liners. Or as A64 says his 4JH has dry liners, maybe just early 4JHs. I was actually under the impression that 4JH and 4JH2 used the same block, but maybe not. Anyway, mystery solved. 4JH series are have dry, borable, not easily replaced liners, except for the early ones.

This document may be helpful; it gives some very basic info about the blocks etc.

[Wotname]

Originally Posted by CassidyNZ

Attached image taken directly from my genuine, original Yanmar-issued 4JH engine manual.

I'm guessing others have different views, I guess its up to them to post.

The next page of the manual goes on to explain liner heights, etc.

I posting this in the interests of being helpful rather than argumentative

The attached image shows a 3 cylinder block so I'm wondering if you have attached the wrong image by mistake??

[CassidyNZ]

Originally Posted by Wotname

I posting this in the interests of being helpful rather than argumentative

The attached image shows a 3 cylinder block so I'm wondering if you have attached the wrong image by mistake??

No I believe the pic of a 3 cyl block is simply there to indicate how the sleeves are removed. The manual does not cover series of models, it is 4JH-specific. If you google Yanmar sleeve kits you’ll find that there are several models that use wet liners and the removal/installation is the same.