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Old 24-08-2018, 14:39   #46
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Re: Bore Honing Without Engine Removal

A couple of things here.
1. Starts easily would indicate the compression is good.
2. Burns very little oil indicates bore and rings are good.

So I think you may be premature in wanting to hone the bore,---so why the smoke? could be many things like out of calibration injectors to a buildup of carbon in the exhaust elbow but you do say it has what YOU would consider excessive blowby,---which may be a subjective opinion. I don't have any experience with your engine as I have an antique Perkins 4.108 but I would try to remove the blowby from the equation without any mechanical intervention. Take a long hose from your blowby nipple on the engine to someplace overboard and see if the engine still smokes so much,---that would at least confirm or eliminate it as the source of the smoke.

It would seem logical that blowby oil dumped into the intake would cause smoke so perhaps we could take a hint from modern auto diesels with their emission control devices and utilize some type of Blowby oil separator and reservoir device https://patents.google.com/patent/US6024058

Who knows, --this might be the solution to a lot of Smoky Yanmars
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Old 24-08-2018, 20:33   #47
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Re: Bore Honing Without Engine Removal

Hello Dockhead

I'm a bit late to the party but I recently did almost exactly what you are proposing on my JH2E, so maybe my experience will be of some help. I'm also assuming that your evaluation of the cause is correct. Running well but smoking at 830 hours makes it very likely that it has glazed bores - mine had the same symptoms when I got it at 1120 hours. After putting up with it for a couple of years I finally fixed it two years ago. My Yanmar doesn't smoke (now!). Yanmars don't need to smoke but glazed bores do seem to be more common in Yanmars - I have no idea why. Maybe it's my imagination.

As for doing it in place, that is absolutely possible if you have enough room to remove the oil pan - don't forget that you need to pull the pan down to clear the oil pickup, so you need the depth of the pan in clearance under the engine to drop the pan into, so that it can be slid out. ('hope that makes sense). Once the pan is out of the way the big end caps (rod caps) can be unbolted and the piston/rod assembly removed through the top. Also I would imagine that cleaning the gasket surface on the bottom of the block for the new pan gasket would be quite difficult. I didn't have enough room so I used a board and some straps to move the engine into the cabin.

My bores were perfectly round and without any wear or taper but were glazed so they were honed and new rings installed. The pistons were perfect so I cleaned them and had the crowns ceramic coated and the skirts anti-friction coated - not really necessary but I used to coat the pistons in race engines, so why not? It reduces heat transfer and also makes it harder for carbon to adhere to the crowns... at least in theory. There was a little play in the valve guides, so they were replaced along with the seals - the new ones also have a little play (less but not that much less) so I'm not sure if it was really necessary. The exhaust valves were replaced and the seats lightly cut as there was some pitting. The inlets were fine and were just lightly lapped. The valve springs were tested and reused. I replaced the big end bearing shells, just because it was already apart, but in that there was so little wear anywhere I looked, I didn't disturb the crank or cam.

I terms of cost, it came to just under $2k US for the parts including the gaskets, coatings, new engine mounts (which were surprisingly expensive) and all new hoses. I did all the of the labor. BTW, the injectors were tested and were fine.

One other thing; it took much longer than expected for the rings to bed in and the smoking to stop, especially when cold. Maybe it was because I used a slightly coarser hone that I would have liked to. I didn't have the correct size and the one I wanted was back ordered. I used cheap oil for a couple of hours to flush out any debris / particles (about 6, 20 minute heat cycles with varying throttle and partial load) and then changed to regular Rotella, Whatever you do, do not use synthetic until it is fully broken in (if at all).

It now doesn't smoke or use any oil. Really! At least not enough to register any change on the dip stick between oil changes.

Personally, in your case, I would pull the cylinder head to see exactly what you are dealing with and proceed from there.

Other thoughts:

If the bores are glazed but are round, don't have significant wear (no step), then a flex hone / ball hone / whatever you want to call it hone, is absolutely the CORRECT type of hone. Other types of hone are used in other circumstances but can remove too much material in this scenario. You are already at the correct size and want to remove as little material as possible. This is what I think; This is what Yanmar thinks; Many, many others think so as well. I only differ from Yanmar in that I use honing oil.

After honing, clean the bores by wiping with paper towels and wd40 until they come back completely clean. Then use paper towels and engine oil until the towels come back completely clean. A lot of paper towels. Then do it again... you missed a bit.

I don't believe that running low on oil will do anything to help.

Glazed cylinders are very hard and I don't think using Synthetic oil such as T6 will help and may make things worse. It's not really the synthetic part, but that synthetics have a high TBN because of the extended change intervals. This is a cause of cylinder polishing in lightly used engines. I've had this argument many times so I won't rehash it. See these links. Anyone who disagrees - that's fine... it's your engine.
Oil for yacht engines – Cox Engineering
Bore glazing and polishing in diesel engines – Cox Engineering

There are special high detergent, very low TBN oils that, in conjunction with high load running, purport to cure glazed cylinders. I have no experience with them and am somewhat dubious. I guess it doesn't cost too much to try but I would worry about sufficient lubrication for the rest of the engine, especially with a turbo.

Replacing liners may or may not be straightforward on your engine, your manual will tell you. A good automotive machine shop could probably do it on the JH2E but it can be bored much more easily and one oversize pistons are available. In that your engine starts easily, I doubt that there is enough wear to justify either. It's definitely not junk.

Anyway, I hope that this diatribe is of some help.
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Old 25-08-2018, 23:49   #48
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Re: Bore Honing Without Engine Removal

Dockhead, I don't remember your engine being particularly smokey, certainly had worse. Before you start tearing this engine apart what colour is the smoke?

Black is a fuel problem.
Blue is burning oil.
White is water or blow by.

I suspect the fuelling side of the engine rather than bores.

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Old 26-08-2018, 15:42   #49
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Re: Bore Honing Without Engine Removal

I have had smoking diesels that suspected suffered from glazed cylinders and or stuck oil rings. I filled the jugs with atf and let em sit for 48 hours or so. With either glow plugs or injectors out, crank her over to blow out the residual atf then button her up and run to temperature. May set you right, may not but cheap fix. An oil change is in order afterwards. YMMV
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Old 27-08-2018, 08:04   #50
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Re: Bore Honing Without Engine Removal

Quote:
Originally Posted by Kenomac View Post
...The issue is more likely fuel related.
This is what I would look into before pulling the engine, which would seem the best route if a bore/ring problem actually exists.
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Old 27-08-2018, 08:50   #51
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Bore Honing Without Engine Removal

You can get yourself a really decent lighted borescope for $100 or so, get a small diameter one of course and one that uses a laptop to be the display.
Youíll be surprised at all youíll use it for once you have it, to see inside of your fuel tanks, around the backside of your mast step looking for corrosion, inside of your mast.
And inspecting the inside of the engine bore.
I still think there is nothing to fix, it doesnít burn much oil at all, starts easily, makes good power, doesnít leak anything and is reliable.

However a bore scope will allow you to inspect without taking it apart.

I think fuel wise he has only two real possibilities, incorrect timing and or low Cetane fuel. Iím real sure he had the injectors inspected / cleaned long ago.
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Old 27-08-2018, 09:19   #52
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Re: Bore Honing Without Engine Removal

Carefull with the $100 bore scopes. The lens does not articulate very far and you can't bend it enough to see a valve seat for example. If you want to get a good picture you need to spend more. Like maybe one from Snap-On.
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Old 27-08-2018, 09:19   #53
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Re: Bore Honing Without Engine Removal

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...I still think there is nothing to fix...
Iím real sure he had the injectors inspected / cleaned long ago.
Engine smokes excessively.
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Old 27-08-2018, 10:48   #54
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Re: Bore Honing Without Engine Removal

Buying a borescope might not be the best idea, I've got a couple of them and seem to mainly use em for finding dropped tools in bilges and looking inside fuel and water tanks, never into cylinders. Spend the money on a head gasket and take a good look with a bright light. I'm with the previous posts on the fuel injection being the culprit and wouldn't lift off the head until this is eliminated. White / grey smoke is a tricky thing to diagnose and 2 engines that had this problem recently took a while to resolve. The first was easy , heaps of white smoke and only reaching 2500 Rpm. Blocked secondary fuel filter, the smoke magically disappeared with full power restored with new filter but no good explanation for the amount or colour of the smoke. This was a low hours yanmar 4JH5 turbo series engine. The next engine, 4JHE , no turbo had blown whitish smoke since the engine had been rebuilt, an annoying amount of white smoke and it defied all attempts to diagnose the problem both by the engine rebuilder and later by some really good mechanics who tried everything. Timing/ auto advance/valve clearances/leakage and compression test/ new filters and so on. Finally I gave the mechanic a set of injectors from an identical engine and the smoke went away after he fitted them. None of the smoky engine injectors had the tubular heat shields fitted to the nozzles below the sealing washer, the replacements did.
After the bad injectors went back into my engine ( with heat shields) we ran it up and.... no smoke!!! Maybe it's the heat shields, I don't really know..... but neither engine blows smoke and the owner is happy.
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Old 27-08-2018, 11:10   #55
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Re: Bore Honing Without Engine Removal

Quote:
Originally Posted by Terra Nova View Post
Engine smokes excessively.
I think that is subjective. I have sailed with Dockhead and I don't remember excessive smoke, in fact any smoke. Certainly not compared to my diesel engined rib with an old 4.2 litre Ford until the turbo cut in at 1800 rpm, then we were off

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Old 27-08-2018, 11:36   #56
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Re: Bore Honing Without Engine Removal

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Originally Posted by alaskaflyfish View Post
The old time aircraft mechanics (circa.1950's) up here in Alaska used to take a handful of Bon-Ami powder cleaner (like Ajax) and stuff it into the intake while the engine was running high rpm. They said it was the best way to de-glase the cylinder walls if the break in process was done inappropriately. I would never do it, but on a old lawnmower,,(humm).. If you do try to hone your cylinder walls, piston and crank out of the block is best. Get a good quality rigid hone that is adjustable to .001 of and inch.
I have heard stories of this also, maybe Dockhead can research this for more info.
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Old 27-08-2018, 11:53   #57
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Re: Bore Honing Without Engine Removal

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How much money do you really want to waste??? There is no halfed assed way to fix an engine. What do you really think honing will do? No one polished the bores , the bores are worn period, they may very well not even be round right now from running with the pistons knocking around in the bore. Bon Ami is an aviation hoax. Where does the Bon Ami go after going into the bores?? into the oil, then the bearings, then the cam and valvetrain...... engine junk!!!.
Heck just a gasket kit is $400 plus labor for what a patched up engine. There is NO hone that measures in .001/1000th Hones do not measure, micrometers measure, sorry!!
Follow captlloyd's advice. Please pardon my way of expressing myself, I'm only trying to help!!!
Hones do not measure .001 blah blah blah.......Aviation hoax blah blah blah..

Well here you go genius.
https://www.lislecorp.com/specialty-...-cylinder-hone
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Old 27-08-2018, 12:28   #58
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Re: Bore Honing Without Engine Removal

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Originally Posted by Carl-T705 View Post
How much money do you really want to waste??? There is no halfed assed way to fix an engine. What do you really think honing will do? No one polished the bores , the bores are worn period, they may very well not even be round right now from running with the pistons knocking around in the bore. Bon Ami is an aviation hoax. Where does the Bon Ami go after going into the bores?? into the oil, then the bearings, then the cam and valvetrain...... engine junk!!!.
Heck just a gasket kit is $400 plus labor for what a patched up engine. There is NO hone that measures in .001/1000th Hones do not measure, micrometers measure, sorry!!
Follow captlloyd's advice. Please pardon my way of expressing myself, I'm only trying to help!!!
Its become clear to me that you misunderstand the difference between the word "adjustable" and "measure", or your reading comprehension is unsatisfactory.
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Old 27-08-2018, 14:21   #59
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Re: Bore Honing Without Engine Removal

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Originally Posted by alaskaflyfish View Post
Hones do not measure .001 blah blah blah.......Aviation hoax blah blah blah..

Well here you go genius.
https://www.lislecorp.com/specialty-...-cylinder-hone


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Old 27-08-2018, 14:28   #60
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Re: Bore Honing Without Engine Removal

However in 1979 when I was building Kawasaki turbo drag bikes, Iíd regularly hone the inside cylinders to .001 clearance and the outer two to .0005
You can choose to believe that or not, it was as tight as we could go without scuffing with Wiesco Forged blower pistons.

I did it by putting the cylinder in a rectangle of 2x4ís and using a half inch drill and a hone like was pictured, you could tell by feel, by the drag on the hone as you pulled it up and down just how much metal you had removed to an astonishing degree.

You could take the cylinder over to the parts washer with fresh safety clean solvent in it and wash til your hearts content, and then wipe it with all the transmission fluid you wanted to with clean paper towels until they stayed clean with just tranny fluid on the towel.
I could then take it to a sink with hot soapy water and Dawn dishwashing liquid and get a lot more stone material out of the cylinders, nothing cleaned as well as hot, soapy water.
Of course it would form a light film of rust in just minutes too, so spray it with some oil as soon as itís dry.
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