THE VALUE OF VISUAL INSPECTIONS

That impeller mishap in Alaska unfortunately wasn’t the only time that our lovely little Yanmar got a saltwater shower. The second time was about three years later, in the Marquesas Islands of French Polynesia.

Our trouble this time did not have to do with the engine, but with the propeller shaft seal. Ours is not a traditional stu ng box with flax packing but a mechanical dripless shaft seal. It has two polished surfaces, one that rotates and one that’s stationary, to create a seal around the propeller shaft. A bellows attached to the stern tube holds the stationary disc in place against the rotating doughnut.

The bellows on ours had grown old and brittle and had finally cracked, which we had not realized. When we started the engine, seawater sprayed all over the transmission and aft end of the engine. We quickly shut down and tried to clean up the mess.

Then we tackled the shaft seal. We couldn’t haul out—about 1,000 nautical miles northeast of Tahiti, the Marquesas to some extent remain one of those remote regions where cruising becomes fixing boats in exotic places. Little is available, and you must use all the ingenuity and spare parts you brought with you. So, we had to make the repair at anchor.

First, Seth unbolted the coupler to insert a bolt to act as a press. Then, by tightening the coupler together again, Seth was able to push the shaft aft and out of the coupler with his improvised press. That way he could slip the doughnut and the leaking bellows o the shaft.

Of course, this let water gush into the boat from the stern tube, so he had the new bellows standing by, ready to go immediately. Once that and the doughnut were on, he pulled the prop shaft forward and back into the coupler.

We don’t recommend this technique; it’s obviously much better and safer to do a job like this out of the water. This was certainly an illustration of the value of carrying lots of spare parts, but it was also a lesson in being careful with your visual inspections.

are available. If you have the space in the engine compartment and the money, I’ve heard good things about the Reverso oil change pump, although I’ve never used one personally. Because it is plumbed into the engine, it removes old oil cleanly, adds new oil, and can be adapted to service more than one engine or generator.

On Celeste, which is quite a small and basic boat, we stick to the tried-and-true manual method. Yanmar recommends changing the oil every 150 hours and the oil filter every 250 hours for our engine, and I start with plenty of oil absorbent cloths at hand and around the engine. I snake a pick-up tube on a little oil pump down into the dipstick tube, place the larger tube from the “out” end of the pump into an empty oil container, and pump until nothing more will come out. Then I pour new oil into the filler opening. I change the filter, which is a spin-on type on the side of the engine, every time I change the oil, even though that’s more often than Yanmar recommends.

It’s also very important to change the oil if you plan to leave your boat sitting for a long time and when you resume using it. Dirty oil sitting there can do a lot to hasten the demise of your costly and otherwise reliable engine.

One of the most important things to remember when you change the oil is to run the engine beforehand. This not only makes the process easier, because warm oil is much easier to suck out through that tiny pick-up tube, but it also makes your oil change more effective. All those contaminants you are trying to remove by changing the oil won’t actually be removed (or at least not well) if you don’t run the oil through the engine first. They will have separated from the oil like water separates from fuel, settled to the bottom, and will be left behind as the cold oil is removed. Then all your labor will have been for naught as those contaminants mix with the fresh oil the next time you run the engine.

While you have the engine accessible for these maintenance tasks, you might as well make a thorough inspection looking for leaks, rust, and things like cracks or wear. Check, clean, or possibly replace the air filter, the exhaust/water mixing elbow, the belts for the raw water pump and alternator, and the electrical connections. Check the coolant level and look at the fuel lines, making sure they aren’t chafing or hanging loose.

Although diesel engines on sailboats are auxiliary to the sails, they are supremely useful machines, and it’s worth putting in the effort to keep them in good shape. If you keep to a regular schedule, it becomes second nature, and every oil and filter change is easier and quicker than the last. With regular maintenance, you can have a dependable engine working for you as long as you own your boat.