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Freeing up a flooded and corroded diesel

Jan 1, 2003

The eight-horsepower diesel engine in Pelorus, my 20-year-old Paceship 26 sailboat, has been a reliable, valued asset over the 10 years I've owned it. Previously, my boats had outboards, which I hated, and I had resolved that my next boat would have standing headroom and a diesel.

During the summer I change the lube oil every 35 to 50 hours according to the engine hours gauge, replace the fuel filters at 10 hours, then 30 to 60 hours, depending on the vacuum gauge, which I also installed.

Each winter, like most boaters, I winterize the engine by running fresh water through the system and finishing off with a slug of anti-freeze. Finally, I shut down the fuel line at the tank, change the lube oil, and clean the filter. I am somewhat fanatical about this, and do it religiously with the expectation that in spring the engine will fire up as it always has.

Usually I turn it over after a long period of inactivity with the hand crank before firing it up in order to get engine lube oil through the system and onto the rings and valves. Imagine my surprise this year when I tried cranking it by hand and it wouldn't turn over! At first I thought I hadn't released the decompression lever properly, but, no, the engine was seized.

Although the boat had been in the water for about six weeks, I hadn't noticed earlier because there had always been wind and I was on a mooring. I prefer sailing, and with solar panels producing a total of 40W, I didn't need to run my engine for electric at all. But with my vacation coming up in three weeks I knew I would need an engine. I had to make the long trip from N.J. to Martha's Vineyard and Nantucket, including the trip past New York City, through the East River and past Hell's Gate.

I grabbed the shop manual, a well-thumbed present from the previous owner. In it, among suggestions for why it wouldn't turn over, was "blockage." I couldn't think what was blocked, but out of desperation for what else it could be I removed the intake manifold (held in place by two easily removed bolts), opened the intake valve, and out poured about a cup or more of water, mostly anti-freeze. Hmmm! I then removed the water hose from the exhaust elbow, and out came another quart or so, siphoned back from the exhaust line.

The water muffler had overflowed and backed into the engine through the open exhaust valve at some point, and now the single horizontal piston was seized by its rings to the cylinder wall. What to do?

At first I panicked. After all, I was on a mooring, not in a marina. Getting the boat to a mechanic without an engine would require a tow. Although I have insurance from Boat/U.S., I'm reluctant to use it, but I thought I'd call the guy and hear what he suggested. The answer was, basically, several hours' tow at $155 per hour. Yikes!

However, a friend suggested the equivalent of a marine shade tree mechanic who had fixed my friend's engine after my friend dropped a wing nut into the air intake - while it was running. Anybody who could work such a miracle would be worth talking to. I called the number and got an answering machine. I kept calling and finally reached him that evening, at dinner time. He was a busy guy, but he offered to meet at the boat yard where I keep my dinghy - that evening!

His name was Doug. He was young and seemed quiet, knowledgeable, considerate, competent, and well equipped, working from a truck. It turned out he had learned from his father and took over his business when his father retired. He unpacked a heavy tool kit, and we went off in my dinghy to my boat on the mooring, about a quarter mile away. I showed him the engine and sat on deck out of his way.

There issued next a series of clanks and thumps as he worked on the engine. He was unable to free it immediately, but he adjusted the valves so that they were closed, removed the injector, filled the piston with something from a bottle called CRC, a liquid for freeing rusted parts, and told me it could take a few weeks. And, he said, try cranking on the handle every so often. He also suggested that even if he removed the head (my idea) the engine would still be seized. Best to wait for the CRC to work. Okay, I agreed, but the clock was ticking.

Next weekend, I sailed. And when I anchored, I cranked the handle. Nothing. For two weeks. Nothing. I couldn't stand it. I called him back, and he suggested, okay, try putting a 24mm wrench to the big nut on the main pulley at the end of the crankshaft. I could even try tapping it with a hammer - lightly. I found that an open 24mm wrench would almost fit. After three hours or so of light tapping, the nut resembled a wrecked car and the wrench wouldn't fit, but the pulley had turned about a half revolution. Visualizing the process, I imagined the piston seized at the bottom of the cylinder, with the cylinder walls full of rust, and highly resistant to motion, and that I had moved the piston to nearly the top. Perhaps at the top it would be easier to head back down the piston if the rust was freed. However, the nut was shot.

I did notice that the pulley had four evenly spaced and tapped holes, for a power take off, I thought. Using paper, I made a pattern of the holes, went to my local welding shop and had him cut a five-inch square plate out of 3/8-inch steel. He drilled a 3/4-inch hole in the center and bolted a nut to the top of a bolt and dropped that into the hole, welded it, and ground off the protruding threaded bolt, so that the bolt head and nut were on one side, and it was smooth on the other. I then drilled holes to match my pattern, slightly oversized because you never know. Back on the boat, they fit perfectly. I bolted it up, and, using a 1 1/8-inch socket on a breaker bar, I worked the handle back and forth, a little at a time.

After a total of one hour of trying, it jerked a quarter turn, then it was free! Somewhat unbelieving, I spun the handle through several revolutions to make sure it wasn't a fluke, and then called Doug.

The next day we met around five. We blew out the CRC by running the starter with the valves open and replaced the engine exhaust elbow as the old one was eight years old. He bolted the engine back together and reset the valves. Then re-tried starting it. At first, the engine would run for a few seconds, then die. It started okay, but sounded fuel starved. Each time we bled the fuel line. But each time it would run a little longer. Finally, after about 10 tries or so, it ran perfectly.

The culprit seemed to be the exhaust line. It should have had a loop from the water muffler up, then down to the transom. There was no loop. There may have been one, but who knows? Possibly it was the exhaust elbow, a hollow casting for injecting exhaust water into the exhaust for cooling it. Possibly the elbow burned through and the water leaked back into the engine. Doug suggested that exhaust elbows should be replaced at six or eight years anyway - about 700 hours in my case. The next day, I replaced the worn throttle cable, ran the engine for about five minutes, put it in gear, and motored a mile or so; then I went back to the mooring. Perfect! I replaced the lube oil and cleaned the filter. I'll do it again at 10 hours, to clean out any residual water.

This was an experience I wouldn't repeat if I could avoid it, but boy, do I know more about diesels now!