Getting techs to look at the engine has been a challenge. Everyone is booked solid for weeks upon weeks out. Neither Diversified nor Chesapeake Dockside had any availability for over four weeks. At the suggestion of the yard manager, DJ, I reached out to the former owner of BayShoreMarine, a man named Jeff. He was leaving town and had no time to work on the engine but he did come by the boat on a Sunday no less to take a quick look. It took him all of a minute to determine the turbo was toast. He also pointed out the the oil cooler was on the verge of failure due to extreme corrosion and that the circulating pump was also failing. He said the oil return line from the turbo also needs to be replaced. 

The stock Yanmar turbo for these engines is crazy expensive but with the help of Diversified a stock unit but not branded with the Yanmar logo was found for a significant discount. As it turns out, the turbo and exhaust manifold on the engine were from a 4JH-2TE. It's not clear whether or not this had any effect on performance but it certainly wasn't factory correct. The only difference we could determine in the exhaust manifolds was the 2TE manifold has an extra coolant supply barb that cools the turbo. The TE version has no such barb so after cleaning my existing manifold thoroughly I put a bronze plug in the hole. It seems to work. 

Upon removing the oil cooler, to my shock and horror, I found that the bell housing covering the flywheel had corroded through. For a moment I thought it was "Game over, man" but then realized I hadn't been losing any oil nor transmission fluid. I tried as best as I could to use an endoscope to see if I could see anything but once again endoscopes leave a lot to be desired. I decided to move forward since it does not seem to be a problem at the moment. Before any extended cruising I suspect I'll separate the engine and transmission to get a much better look to see if anything needs to be addressed. Using a combination of dremel tool bits I cleaned up all the corrosion and then wiped everything down using alcohol wipes.

I used Steel Stick from JB Weld to fashion a plate to cover the hole.

Wearing latex gloves, I let it set up in my hand enough so that it would not sag significantly and then molded it into place. I had tried MarineTex but couldn't get it to work for me. I suspect I could have needed some fiberglass matt but I've never done that work before. The Quick Steel seems to have worked pretty well. It sagged a little bit before hardening completely so as a test I turned the engine manually using a wrench on the main pulley. It was surprisingly easy to turn. 

I then painted all the rusted areas using rustoleum followed by Yanmar Grey. 

Jeff also strongly suggested pulling the exhaust manifold core and soaking it. So with much effort I pulled that. I ended up having to use a 2+ inch dowel to hammer the core out. I sprayed the ends with Kroil penetrating lubricant and let it sit for some hours before trying. The interior of the exhaust manifold was incredibly dirty. 

So I removed the manifold as well and took both home to soak in descaler that I picked up from West Marine. I also soaked the end caps, the radiator cap and the cross pipe from the front of the engine. After this I spray painted all of them. For the manifold and end caps I did a base layer of rustoleum followed by Yanmar grey. For the new water pump, which was green, I just sprayed and the copper pieces with Yanmar Grey. 

While I had everything apart I took the time to clean up a significant amount of previous owner wiring mess which is covered in a separate project:

Yermo

5 days ago

Project (291437)

Yanmar 4JH-TE Wiring Harness Fiasco

The wiring harness for my Yanmar 4JH-TE is a serious mess of previous-ownerin' nonsense. It was difficult to figure out how everything was wired with all the splices, stacked connectors, and bundles of unrelated wires wrapped together in electrical tape. 

With everything apart I had much better access to the bilge so I took the time to thoroughly clean the buildup of years of grime and accumulated oil using a ton of Dawn dishwashing liquid, too many paper towels, and a sacrificial toilet brush which seemed to work pretty well. It was nevertheless a multi-hour project. 

Putting everything back together was much more painful than I imagined. Getting the oil lines to line up with the oil cooler and turbo took forever and was very draining. There's an uncomfortable amount of torque on those pieces. Otherwise reassembly went well. 

Unfortunately disturbing the engine wiring harness caused a number of electrical gremlins so I bypassed the panel so I could test the engine. I'm replacing the engine panel and harness as it is so a temporary bypass was not much of an issue.

And after all this work, the smoking problem is not improved. The engine seems to run a bit stronger but will still not turn over 3000 rpms and spits out black smoke. The next things to test will be the injectors (again), and a compression test followed by a leakdown test. 

The real fear is that maybe a ring or valve is bad which would require very time consuming and expensive repair work. However, there is no smoke or coming out of the PCV valve hose. Oil and/or smoke coming out of the hose would be an indication of worn rings letting compression pass by into the crankcase. I've seen video of people pulling the oil fill cap and letting it sit on the engine and it just now dawned on me that this would be a way to see if there's excessive pressure in the crankcase. I'll have to give that a try.