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Old 20-08-2013, 14:23   #1
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Rebuilding my Yanmar 4JH2E

I finally completed the rebuild of my sailboat's diesel engine, a Yanmar 4JH2E. I figured I'd share the prior write ups and the end of it all here for you guys. Before going into this project, I had practically ZERO mechanical skills. I learned everything as I went, relying on some key books on marine diesel engines and the internet. I tried to do everything myself except where the cost of the tools was too much or the job was way out of my league (machining the head). These write ups were taken from my blog about my boat...





With the deck paint finished (sans non-skid), I am switching gears on boat work. I’ve been doing a bunch of different odd jobs such as rebuilding the deck hatches, restoring bronze hardware, and working on getting the drains installed on deck.

I also decided it was time to start diving into the engine project. The engine was removed from the boat early last year and has sat on the ground of the yard untouched this whole time. I recently moved to a place with a garage, and I wanted to get the engine protected and in a space that I can begin to work on it.

The engine itself is a Yanmar 4JH2E, a 52 hp naturally aspirated marine diesel. This is Windsong’s second engine, and was installed in 1992. It only had 900 hours on it when I purchased Windsong, and the young engine was one of the selling points for me. However, the engine had sat in the closed up Windsong in the Florida heat for about a decade, and the destructive humidor environment caused havoc to the engine’s parts. The paint had peeled away in many spots, rust and corrosion were having their way on bolts and a few certain parts, hoses were cracked and loose, the motor mounts were nearly rusted through, the shaft seal was leaky, etc. However, beyond all that, the engine started up quick and ran smoothly from the beginning. Despite its looks, it worked wonderfully.

The trouble began on the first time I took Windsong out for a ride by myself. For the full story, refer back to this post. Long story short, the engine’s water pump impeller wore out during that ride and caused the engine to overheat due to lack of cooling water. At this point in time, I knew practically nothing about how these engines worked, so I just added some coolant to the tank and drove the boat home while it was overheating. It was probably a total of 15-20 minutes, and that time of overheated running has caused loads of concerns for me.

We eventually got the impeller replaced and the engine ran wonderfully again. I put roughly 100 hours on the engine when I took Windsong around Florida, and it ran smoothly the majority of the time. The only problems that we faced dealt with a very dirty fuel tank, some loose hoses, a poor shaft seal and bad motor mounts. When it was getting clean fuel, it ran great.

So what do I plan on doing to the engine now? I had contemplated a full rebuild, but these things typically last 5,000-7,000 hours before a rebuild is needed. However, given that I have it out of the boat and in a great working environment, I will give it a good restoration and possibly dig deeper than necessary for educational and experience purposes.

The plan right now is to:

-Clean thoroughly
-Remove and replace all rusted/corroded bolts and fittings.
-Ensure all good bolts can be loosened for future repairs (use anti-seize compound)
-Replace Starter Motor (works, but is corroded on outside. Will refurbish old one as a spare)
-Replace Motor Mounts (all 4 were rusty, two actually rusted through and broken)
-Replace Air Intake Silencer (Rusted enough to where the brackets will not function)
-Replace all water and fuel hoses (including some exhaust hoses)
-Replace alternator (use existing as back-up, upgrade amperage output in new)
-Clean heat exchanger/exhaust manifold, replace gasket
-Replace thermostat and gasket
-Replace mixing elbow gasket
-Replace belt
-All filters, fluids replaced

Related issues:
-Thoroughly clean fuel tank
-Get shaft inspected
-Replace shaft seal
-Replace Cutless bearing

Beyond all of that, there are a few things I can optionally do. This really goes into the question of “if it ain’t broke, don’t fix it”; or “check it out now while it is easily accessed”. Since I did run the engine hot for a bit, the biggest question mark is the condition of the head and head gasket. Therefore, I might open up the head to get a look at the condition under there. This would require a replacement of the head gasket, regardless of condition; and getting the head checked for any warping. If I open up the head, however, I might as well do some extra work such as cleaning and checking valves, checking injectors, etc.

Right now I am leaning towards opening up the head for educational purposes and piece of mind that everything is OK under there. I like the idea of dissecting the engine now, and knowing how to do it for the future, versus having to do it in the boat and in a confined and awkward space. If I have to do it in the future, I will at least have the experience to know how to do it.

If you have any engine experience and think I should do something not listed here, please chyme in.

Check out these galleries for engine goodness.

Engine part 1 – Disassembly Reference Photos – Facebook Photo Album

Engine part 2 – Restoration – Facebook Photo Album

Some choice pics of getting the engine from the boat to my house:























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Old 20-08-2013, 14:23   #2
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Re: Rebuilding my Yanmar 4HJ2E

Disassembly and cleaning is coming along nicely.









Fresh water pump, pipes, hoses, etc…



Disassembled heat exchanger



Starter, mixing elbow..



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Old 20-08-2013, 14:24   #3
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Re: Rebuilding my Yanmar 4HJ2E

Long time no post! I have been busy working on the engine and the interior of the boat, but am in limbo on a lot of projects. Writing about a project while it is not complete is frustrating to me, it is much easier to write once something is complete so I can tell my lessons learned and whatnot. Without a whole lot to report these days since I am in the middle of a lot and finishing nothing…writing has been stale. Here is a tidbit of a frustrating piece of the engine rebuild…

One of the most frustrating and difficult things about rebuilding the engine (and the boat as a whole) has been rusty/corroded bolts & screws. Make the bolt hard to access, and it is even more difficult. A primary job I have put before myself in this engine rebuild is to make sure all rusted and corroded bolts are removed and replaced while the engine is out of the boat and I have easy access to all angles of the engine. I do not want to be stuck in some muggy anchorage in the middle of nowhere struggling to remove a fully corroded bolt to replace an engine part…might as well get it done now so repairs are easier in the future.

Unfortunately, there were quite a few of these trouble bolts, and they have caused me a lot of grief. I’ve learned a lot of tricks to get them out: using the correct wrench (six sided > 12 sided), breaker bars, penetrating oil, heat, vice grips, etc. Though along the way I have become quite adept at getting most of them out, one set of bolts in particular had given the business. The bolts in question are those that hold on the exhaust elbow onto the exhaust manifold:



They were easy enough to access, but they were absolutely corroded throughout. Since the heads were corroded down, the correct size wrench wouldn’t even fit on them anymore. I quickly had to resort to vice grips, but no matter how tight I got them and how much leverage I was able to get, these things didn’t turn at all. I sprayed the bolts with penetrating oil twice a day for about a week before trying again. I tightened the vice grips as hard as possible and put on an extra long cheater bar for maximum leverage. When I started on the first bolt, I thought I saw a small bit of rotation so I kept applying pressure. Sure enough, rotation was afoot! Unfortunately, that was the bolt head breaking off from the bolt. This happened with 3/4 of these bolts, only one of them successfully coming off.

I was left with this:



From here I did some research on what to do next. While I pondered my course, I straight up soaked these bolts in penetrating oil for about two weeks. I figured with such a long soak, they were bound to come out somehow.

After soaking for a long time, I figured I would try to cut a slot in the bolts with my Dremel tool and use my impact driver to turn them out. You can see in the top left bolt in the prior picture I had tried this before the oil soak, but it wouldn’t budge. So after two weeks of soaking, I went at it again only to break off the remaining pieces of bolt.

So by now I had tried everything I could think of with no luck. Many people would suggest using left handed drill bits or an Easy-Out to turn them out. After speaking to some people who have used that technique before… I decided that was a horrible idea. If these bolts were truly rusted in place, the Easy Out would just break off in there and create an even bigger problem.

The last resort was to drill out the bolts and use a Heli-Coil or Timesert treaded insert. I was quite ready to go this route, as many people had nothing but positive things to say about each product. However, I became quite anxious about the precision needed to drill straight down the center of these small bolts. Without a large drill press, getting a perfect center drilled in the bolts seemed nearly impossible. I contemplated using a center punch and drill guides, and even practiced on a few other bolts. However, I could never get it right.

If I screwed this up, I could end up drilling a hole in the wall of the heat exchanger and ruin the whole unit..and a new one is not cheap (list for $2k+!). For the first time in this entire rebuild, I threw in the towel and decided to seek professional help.

I took the whole unit to a machine shop near me and asked if they could do the job, and they said it wouldn’t be a big deal at all. Since there is risk of drilling into the wall of the heat exhanger, and the fact that it is aluminium, they decided using stainless Heli coils were the best bet.

I just got the unit back and they did a great job. Back to the rebuild…





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Old 20-08-2013, 14:24   #4
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Re: Rebuilding my Yanmar 4HJ2E

The engine is now as disassembled as it is going to get and ready to be put back together.



The deepest I’ve gone on the engine is the removal of the cylinder head. I described in this post why I am doing this much work on the engine. I had concerns about the head gasket and the head itself after running the engine overheated a while back. I poured over books, forums, spoke to the pros and developed my game plan to get the engine back in order. At this point, I only need to order a few extra parts that I haven’t already and it will be ready to be reassembled. Nearly everything on the engine was relatively easy to take apart, with the exception of areas with corroded and/or worn bolts. Everything I’ve taken apart has been thoroughly cleaned, inspected and prepared for reassembly and painting.

The toughest part came when I started the process of removing the cylinder head. I first needed to remove the injectors, which are tricky little buggers requiring some ingenuity to pull out. These are not threaded in, and once they are in there they are pretty snug. I developed a custom injector puller after much research and for the help.



The tool:



Removed, dirty injectors:



I then took the injectors to a pro to get cleaned, inspected and tested. One injector had to be fully replaced, the others needed some work but ended up OK



Next up was the removal of the cylinder head. First the valve cover came off, the rocker arm assembly removed, and the head bolts loosened in the correct order:



Head removed:





Once the head was off I took it to the pros to get a valve job done, the head checked for warpage, and a full cleaning. Turns out the head was pretty warped, as I was fearful of, and they had to machine it flat again. Fortunately, that wasn’t too bad $$ wise and the head came back looking shiny and ready to roll.



Cleaning the gasket off the block was a pain, particularly when trying to not scratch the surface and avoiding having pieces of the gasket falling into the engine holes. But I eventually got it all cleaned off, and she is now ready to be put back together.



I’ve ordered and received most of the parts I will need, however, the list of needed parts has grown a little bit since I put in that order. I resigned myself to ordering some of the hoses from Yanmar, as many have custom bends in them that I cannot make with regular engine hose. For a length of 6″ of hose, Yanmar charges $25 just because it has a custom bend in it! Oh well. Once the parts are in I will torque down the head, get the valve clearances squared away, and begin to reassemble and paint.
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Old 20-08-2013, 14:25   #5
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Re: Rebuilding my Yanmar 4HJ2E

This post continues the engine rebuild, the previous post can be found here.

As of that last post, I had all of the necessary fixes finished and ordered all of the remaining parts. The parts came in but before I could reassemble, I needed to paint everything.

For color I had originally planned on painting it silver/metallic much like the original color Yanmar uses. However, the more I thought about it the more I wanted to paint it something more unique and entertaining. I spent so much damn time rebuilding this thing, might as well make it look cool. I pondered some darker colors but realized that it needs to be light and bright so that problems can be seen easier (leaks and whatnot). Since I had the whole thing taken apart already, I might as well mix it up and have some parts different colors.

I ended up choosing a pattern of yellow with aluminium color parts. I used Dupli-Color Self-Etching Primer as the base coat, important for aluminium surfaces. I stuck with the same brand and used Dupli-Color High Temperature Engine Enamel for the paint job.

Before painting every surface was meticulously cleaned. I also tried to get most of the original chipping paint off that I could. Painting was rather easy, the hard part was getting everything taped off correctly so that no mating surfaces were painted and everything was protected against that paint that needed to be. Just followed the directions on the cans of primer and paint, and let it rip:

Priming:













Painting:

















With everything painted, it was then time for reassembly!
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Old 20-08-2013, 14:26   #6
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Re: Rebuilding my Yanmar 4HJ2E

Once the engine and its parts were painted, it was then time to begin reassembly! Not as easy as it sounds, there were a few specific procedures that needed to be done with care. First was mounting the new head gasket, putting on the head and correctly torquing the head bolts. Getting the right torque on those bolts, and in the correct order was important. Unfortunately, when torqing down the bolts much of the new paint came off the bolt heads. No big deal really, I’ll touch-paint in the end after I’ve re-checked the torque after running.

New Head Gasket on



Head back on, bolts torqued





Next was the rocker arm assembly and push rods. This step required adjusting the valve clearances, another tricky procedure. But as with everything else I’ve had to learn, reading the books and finding some good guides online made it pretty damn easy. This video really helped me visualize the procedure:



Rocker assembly and push rods on, valve clearance adjusted





The rest of the assembly was much easier. Put on new gaskets or o-rings, torque bolts to the manuals specifications.



Intake Manifold, High Pressure Injector lines in place



New Intake Silencer, new fuel and water hoses in place



Nearly fully assembled, front view. Hoses, belt, Alternator, heat exchanger in place







The only remaining items to be put on are new oil and fuel filters, a new breather hose, and the wiring harness. Once those are complete it will be test run time!



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Old 20-08-2013, 14:27   #7
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Re: Rebuilding my Yanmar 4HJ2E

mentioned in the last post that I only had a few items remaining, but unfortunately those items took me many months to complete. I sort of left the engine at that state and ignored it for a while as the job of sealing up the boat became a bigger priority.

The hold backs came in the form of the transmission, alternator, starter and wiring. The transmission was sitting by the engine for the whole rebuild, I figured it just needed a paint job and that was it. But while it was sitting I noticed that it began to leak oil out of the shaft seal, so of course that needed to be fixed. Turns out that the nut holding the coupler on was a very special type of nut that needed a very expensive type of wrench to get off. I did the math and it would cost less for me to take the transmission in to get a full service as well as the seal replaced than to buy the actual tool. So I took it in to a local shop and got it fixed up, sealed up and working well. It got a paint job and was ready to be installed.

The tranny fresh from the shop, ready to be painted. Note the weird nut holding the coupler on.



I installed the starter motor and alternator. As far as I knew, both of these pieces worked fine before I took the engine apart. It would always start up very quickly so I had confidence in the starter, but I didn’t know for sure if the alternator was going at full strength. I assembled the engine and connected the wiring harness, just to see if the starter motor would crank over. I turned the key and nothing happened. Welp…time to trouble shoot this mess.

In order to give my self some piece of mind, I took the starter and alternator into a shop to get checked out. Turns out the starter needed a new solenoid, and the alternator was putting out only about half of its rated amps. I wanted to upgrade the alternator to a higher output unit anyways, so I purchased a new 80 amp (55 amp was the original) alternator. The starter was in decent shape after the solenoid replacement, but the shop had a smaller and more efficient starter in stock that I could buy at a decent price. I bought it and will have the original one as a back up.

Old and new: Starters & Alternators.



Then came the issue with the engine wiring itself. The original wiring was poor quality, un-tinned wire without heat shrink terminals. The connections were loose or corroded, and in the end I decided it all needed replacing. Instead of shelling out big bucks for the official Yanmar wiring harness, I rebuild the wiring myself using high quality materials. In addition, I had to re-wire the instrument panel as it was a complete mess of corroded terminals, and I needed to add new male-female connections to replace the wiring harness.

What have I gotten myself into.



The great part about having to re-wire the engine and instrument panel, as well as the alternator was that I got to learn all about marine DC electricity and how to efficiently put together safe and relivable connections. All of which I will need to do plenty of when re-wiring the boat. It forced me to break out the batteries to see how they are, to start to figure out how I will be wiring up my charging system, and overall mapping of the electrical system. The engine and instrument panel wiring will probably be one of the most complicated electrical nightmares on the boat, so getting it out of the way early leaves me full of confidence to tackle the rest of the electrical system.

All of that took a bit of time working on and off while focusing on other projects as well. This weekend I finally had all of the pieces together, and decided to see if I could crank the engine up…….
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Old 20-08-2013, 14:27   #8
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Re: Rebuilding my Yanmar 4HJ2E



Other view from the phone camera I was trying to (unsuccessfully) hold…




and with that…the engine project is complete!! I just need to put her back in the boat when the engine room is all ready, align the engine to the shaft, and hook it up.

To put this all in perspective, I had ZERO mechanical skills going into this entire project. Now I just finished a major engine rebuild successfully. There is no excuse for you to not learn the skills you desire, with the internet at your fingertips you can find all the information in the world…or at least get pointed to a book with the info.

Very very happy right now
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Old 20-08-2013, 15:11   #9
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Re: Rebuilding my Yanmar 4HJ2E

Well done young man on a splendid presentation of your rebuild! Not keen on the yellow paint but whatever floats your boat. The Yanmar is a beaut engine, I have a 4JH3B in my Catalina....interesting you have a doubled up oil cooler configuration!?
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Old 20-08-2013, 15:53   #10
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Looks like I'll have to abandon my plans take that old nasty Yanmar off your hands, and provide you with a genuine authentic Atomic 4 diesel for your restoration project, complete with a "custom" connecting rod.

Seriously, that's an impressive undertaking, kudos to you!
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Old 20-08-2013, 17:37   #11
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Re: Rebuilding my Yanmar 4HJ2E

Quote:
Originally Posted by Amnesia II View Post
Well done young man on a splendid presentation of your rebuild! Not keen on the yellow paint but whatever floats your boat. The Yanmar is a beaut engine, I have a 4JH3B in my Catalina....interesting you have a doubled up oil cooler configuration!?
thanks! I'm not sure about if the oil cooler is doubled up . But this is what it looks like, the two pipes above the flywheel

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Old 20-08-2013, 17:38   #12
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Re: Rebuilding my Yanmar 4JH2E

Quote:
Originally Posted by SoloBob View Post
Looks like I'll have to abandon my plans take that old nasty Yanmar off your hands, and provide you with a genuine authentic Atomic 4 diesel for your restoration project, complete with a "custom" connecting rod.

Seriously, that's an impressive undertaking, kudos to you!
hehe I'll definitely pass on the Atomic 4.

Thanks for checking it out
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Old 22-08-2013, 08:24   #13
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Re: Rebuilding my Yanmar 4JH2E

Great job, continue on now to all the other small projects and soon you will be a sailing and motoring boater again. Again Great job on the project and the presentation.
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