Yanmar 2QM20 Diesel Maintenance

We aquired our 1980 Morgan 323 Mariola (then El Caribe) in June of this year. Among some of the many discoveries during the last few months, one was that our salt water cooled Yanmar 2QM20 diesel engine had anti-corrosion zincs that require replacing. When we purchased the boat it was in decent shape but you could tell it was on the downhill slide in regards to maintenance. It was at the point where a decent amount of $$ and elbow grease was needed, probably the reason it was put up for sale. I guessed since the outside of the boat and engine needed cosmetic work, so did the inside. So the other day Cannonball and I put on our greasy clothes and went to work.

Let me just say a few things about my mechanical ability, because there’s really only a few things I’m good at. Taking things apart and leaving them that way. For some reason the deconstruction part is much easier than getting it back together without left over pieces. I mean, I know righty tighty – lefty lucy, there’s no such thing as a metric crescent wrench, WD-40 is magical, you know - the basics. At least diesels seem to be pretty simple, no distributor or electronic ignition wires protruding everywhere.

We now return to taking stuff apart, already in progress.
There are 3 zincs in the motor, two in the front, one in the back. They came out quite easily and were, I think, just ready to be changed. As I peered up into the head, I couldn’t see any salt buildup or corrosion. The only mess was right around the zinc and it scraped out with a little effort. They really seem to do their job. The previous owner had left a bucket load of new spare parts on board and there were 3 new replacement zincs in the inventory. Just to be safe I had picked up two replacement gaskets for the engine plates at Mastry Engine so we had everything we needed. We didn’t however, get the zincs back in that day. As long as the engine was exposed and apart, we decided to embark on a starter problem. See, things tend to stay apart.

Low Conductivity
Since the day we bought the boat it has had this interesting starting quirk – you push the start button and nothing happens, sometimes a faint “click” and sometimes nothing at all. You get nervous, look around for an oil tanker bearing down on you (this is when it happens), push it about 5 times and then the engine turns over. This drives me nuts. I either want something to be busted, or work 100% of the time. I hate not knowing if the engine is going to start. Let’s face it, when you need the engine, it’s usually because there is manuvering to be done. Back to making me nuts – while I was at Mastry picking up my gaskets, I explained the delayed starting problem to the parts guy and asked if it was the solenoid or “magnetic switch” on top of the starter. He said they either work, or they don’t.  Plus they cost almost $200 so killed my idea of just replacing parts until it worked – dammit. He then told me since the boat is 30 years old, it’s a probably conductivity issue. WTF? Old wires don’t carry as much juice. He said that I could purchase a “booster kit” for $110. I think I will just run new wires if need be. Sounds fishy to me – maybe he’s trying to win the company pool for “dumbest customer”, I showed him.

Still not completely believeing that wire loses it’s ability to carry current over age (I mean, come on! it just sits there!) CannonBall and I worked, checking all the connections, volts coming through, etc. Everything worked perfect, volts were 13.5 - the push starter switch, fuses, grounds, battery connections, etc. were good and making connections. What we couldn’t measure was the load being pulled when we tried to start the motor. Finally we just ran a new wire right to the starter and it turned over every, single, feaking time. Had the fellow at Mastry not told me about conductivity and old wires, I doubt we ever would have figured it out. He wins and I owe him some beer. Now, I guess this means I will be doing a lot of rewiring on the boat as well.

Humpty Is Back
Finally the other day I found some time and put the plates that hold the zincs back on. When I started her up (yes, first button push) she ran so cool I could put hand anywhere on the motor. A few days later I degreased and wire brushed the engine, primed and spray painted the rusty spots – now it looks dang good. I bought some type of fancy spray lube that I’m going to hose her down with and hopefully that will keep the exterior rust at bay. I plan on changing the oil – just as soon as I figure out the best way to avoid an environmental disaster.
 

Tagged as: diesel, engine, Yanmar 2QM20