Service/Maintenance

Engine: Yanmar 6LPA-STP2
Hours: 800-850
Age:

I'm contemplating tackling a couple of jobs and considering doing them myself.

Here are some of my thoughts on why I think I need to move in this direction. I bought the boat about 8 years ago. At the time I had the engine surveyed. Everything was great.

Exhaust Elbow

Cast iron elbow looks original. I'm just going with, I assume this is necessary preventative mainenance.

Heat Exchanger

When I first bought the PO had been using teflon tape on the threads of the zincs for several years. Also, I didn't realize I had been missing one of the two when I was changing them yearly.
As of right now, I keep filling my overflow reservoir and it keeps emptying. Very slowly, but it's happening. I suspect i'm leaking AF into the exhaust water discharge.

Clean Turbo

Fuel Injectors

Lately, I'm getting a decent puff of blue/grey smoke in my exhaust at start-up. The engine also seems to be putting out a lot of what looks like white steam when running, however it definitely has a string diesel exhaust smell.

When I first bought the PO had been using teflon tape on the threads of the zincs for several years. Also, I didn't realize I had been missing one of the two when I was changing them yearly.
As of right now, I keep filling my overflow reservoir and it keeps emptying. Very slowly, but it's happening. I suspect i'm leaking AF into the exhaust water discharge.

No idea when the turbo was cleaned last. I'd guess never. The previous owner and I both run it at around 2400. 3200 is WOT. Turbo IS spinning, I can hear the whine.

I'm guessing the exhaust issue is likely either Turbo or injector related.

Questions:

1) Are these doable as DIY for someone who is reasonably able to do mechanical things (Hip bone connected to the leg bone, and I can read absorb manuals). I work in a highly technical field.

2) Am I on the right track with my thinking regarding these issues?

I'll be happy to open a parallel thread to discuss the technical aspects of a specific item if we end up going in depth on any one of them.

I bought my essentially identical 6LPA-STP in 2015 after decades with my twin Ford-Lehman 120s. Except for the time the port engine had to be pulled in 1987 due to the number six piston performing clanky sounding S-turns in the cylinder due to saltwater intrusion on the PO's watch. Until I sold the trawler in 2015, I performed all other routine, and some no so routine, maintenance on those two engines.

The 6LPA is nowhere near as accessible as the almost walk-around Lehmans were, and I am a lot older and better supplied with funding than I was back then, and the turbo being new to me and the high RPM of the Yanmar gave me pause. Thus, after a bit of study on the Boatdiesel.com Yanmar forum, I elected to have a professional I know and trust come to pull and service the intercooler and to exchange the timing belt while I watched. The engine was ten years old with less than 500 hours on it, but I felt the chronological age dictated catastrophic damage prevention measures. A leaking intercooler tube nest is sending saltwater into the cylinders for eventual disaster, and a broken timing belt can destroy an engine instantly.

I have elected to keep an eye on the fuel, oil, tranny coolers and the heat exchanger rather than pull them (yes, I would likely do them myself) because the PO was regularly running a freshwater rinse through the engine every time it was lifter out of the water and put on the shelf of the boat barn where it lived, a practice I have continued as well as an 18-month cycle of running Barnacle Buster through the seawater cooling circuit. Their aluminum anodes (zincs to some) are pulled and checked every 90 days with the lowest one being replaced most often at 6-8 months - all the others drain dry through the Tides shaft seal when the boat is lifted out of the water in my lift behind the house.

The engine is nearing 1,000 hours now and running well with all the regular maintenance performed by yours truly.

As to why you are losing anti-freeze, well, there are other reasons than having it run out a tube nest pinhole in the heat exchanger, but a pressure test on it while you have it removed is a good way to confirm. However, I would suggest you also get a compression test while the injectors are out to check for a blown head gasket/cracked head.

My exhaust elbow is SS. I used to change the elbows on the Lehmans at five-year intervals. I would change out the one you have for new. There is a lot more stress on a 6LPA elbow than the old naturally-aspirated Lehmans.

Have the turbo clearances at both ends checked to decide whether more than just cleaning is needed.

I think MOST of these things are DIY, but I would not attempt a diesel engine compression test. Gas engines ok, but not diesel.

If you do not have the Yanmar engine panel with the proper idiot lights and audible alarms, consider fixing that problem while involved in all this effort to preserve your engine's longevity. My boat came to me with only a single piezo alarm for any one of the six or more alarm conditions available. The oil pressure and the coolant overheat alarm could be checked by looking at the engine gauge cluster, but what about gear oil temp, exhaust overheat, low coolant level, and maybe boost alarm? It's a $33,000 engine (2023 price) before you buy the remove and install services; so, it's worth a darned good alarm system.

Shrew
As to what is DIY and what is not, your comfort level is the ultimate measure. If on the edge, you can start the project DIY and stop when you get to a "No Go" condition, but have your backup mechanic in place first.

HE is not the most likely culprit for a slow leak. a pressure test on the engine coolant system might sus out a different culprit, or even just a close inspection of all pipe to hose, block to hose, pipe to pipe, pipe to block, especially any that are hard to see. Pictures by your phone held down and back in those places where there is no room ore often the answer.

Exhaust elbows can fail early, so some do PM on them at short intervals, as suggested above. If yours is easy to inspect, even if you need to take it off to see the inside, you may be able to satisfy yourself before spending the $$$ on a new one. Corrosion is more of a time determined thing than a usage thing, so your 24 years makes that inspection or replacement a necessary thing. Mine were done at 30 years. One was ready to fail, the other not visibly ready, but a fresh start together made sense.

Your turbo shouldn't need to be cleaned. It will look the same 2 minutes after cleaning. If you pull the elbow for inspection, spin the turbo in place. If it doesn't spin freely, take it to a shop. If it does, leave it alone.

850 hrs in 24 yrs is 35.4 hrs/yr. I do that much getting out of the slip. Is your hr meter working?

Regarding the coolant leak, I would get a radiator pressure test device and check the freshwater system. While it may be going through a leak in the heat exchanger, you could have a slight leak at a hose clamp, gasket, or other place. Find the leak before you fix it. I had a leak on my charter boat where the leaking coolant was evaporating on the exhaust manifold at the head (no antifreeze puddle to trace).

I wouldn't condemn a heat exchanger with 800 hours without finding a problem. Most transmission coolers don't have an anode and usually last several thousand hours. I would pull the end caps if so equipped, and rod the tubes as they are likely partially blocked. Replace the end cap gaskets. While at it, rod the transmission cooler also.

Before doing the injectors, I would clean the heat exchanger, transmission cooler, inspect the exhaust mixing elbow, and inspect or replace the raw water impeller. Steam is a common occurrence when there's still enough raw water flow to cool the engine through the heat exchanger, but the water after the heat exchanger is too hot and being partially vaporized (steam) in the exhaust mixing elbow. If the steam gets too hot, rubber exhaust hose can deteriorate and stink.

Ted

Excellent advice from Keith and Ted, especially the cooling system pressure test. I keep a Stant pressure coolant system/radiator cap tester on hand, but my 6LPA-STP has a "mini" radiator cap/neck which the standard Stant package did not come with and required me to special order. Your engine may not have this issue. When I thought I was having a coolant loss, my Stant tester was most helpful in reassuring me. FYI, the adapters are model 3122 for the system and 3124 for the cap.

do the injectors run through any of the cooling jackets on that engine? possible to lose coolant into the cylinders there? just asking.

Bmarler said:

do the injectors run through any of the cooling jackets on that engine? possible to lose coolant into the cylinders there? just asking.

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No.

Many thanks. That is a lot to think about.

The issue I've been having is getting a diesel mechanic. I had two. One now tells me that if I'm not in his yard or marina, he can't take me. The other is just too busy to return phone calls.

Shrew said:

Many thanks. That is a lot to think about.

The issue I've been having is getting a diesel mechanic. I had two. One now tells me that if I'm not in his yard or marina, he can't take me. The other is just too busy to return phone calls.

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I feel your pain. Friend of mine lives just North of Tom's River, NJ. That area has an amazing amount of boating, comparable to Miami or Ft Lauderdale. He has to pay 2 to 3 hours of round trip drive time to get a qualified Yanmar mechanic to work on his boat. Outboard motors have taken over the sub 40' boat market and that's what the new mechanics are training for. This problem isn't exclusive to Yanmar.

Ted