Engine Maintenance

Engine maintenance and the number of operating hours have a linear relationship. Traveling great distances, it is important.

Yanmar 3YM30AE and SD25 Manuals

Before departure or monthly

In general, before leaving for a long-distance trip, or else monthly, there are a number of easy steps to take to avoid problems. Have a look at the steps below:

  1. Measure the oil level when the engine is cold, insert it all the way in. Make two photos, with date and location, one of the engine hours and one of the dipstick, move it to an album Maintenance. Nice way of keeping track whether or not you are using oil if you do a lot of motoring.
  2. The color is brown to almost black. Gray, creamy or too thin (drip) are all not good. Two causes Water in the oil, diesel in the oil. Both require a repair.
  3. Check the gearbox oil level, take care not to tighten the screw cap/dipstick when measuring. Hand-tight is enough.
  4. Check for spray, mist deposits in the engine compartment, from mini leaks to leaking rubbers of hatches, floor connections, etc, valves. If you have a clean space you will see the change.
  5. Coolant, enough in reservoir, if not top up on the heater exchange. The mixture is clean water and 30-60% LLC.. Coolants from different brands do not go together, then only water.
  6. I look, always empty the water-diesel separating filter and look at the weed filter. (why can’t they be completely transparent?). I don’t open it by default and try to do as long as possible with the o-ring, a little Vaseline prevents drying out and false air. Hand tight.
  7. The check for tension on the V-belt, turn it a quarter turn on the long piece between alternator and drive shaft between 2 fingers. If that is too easy or further, the V-belt is too loose.
  8. I always check the contents of the diesel tank on the gauges. Usually I write the position in the log along with the engine hours. Water inlet is open by default and after starting I always check the outlet.
  9. Before long trips I drain the diesel tank to dispose of any sludge or water collected at the bottom.

Initial 50 hours of Operation

Most vital one in maintenance. And difficult because you need to park the Seawind on the beach or on the hard. Changing the oil in the Saildrives (and the engines) is necessary. New equipment generates debris, factory faults with o-rings etc, tighten bolts to the right torque. All important. Plan your route to be somewhere with facilities.

Annual or after 250 hours

Annual engine maintenance is real work. And in places that are usually more difficult to reach. My Yanmar 3YM30AE operation manual contains a maintenance schedule, oil types, quantities, instructions and so on. And you also need spare parts and a few tools. A small logbook with a pre-standardized checklist where you make some notes, helps enormously at the next turn.


Always change oil and filter all at ones. Again, there are a few handy things to arrange in advance. How much engine (gearbox) oil do you need? That is the amount that comes out and that you have to absorb. Collecting everything at once in an empty 5-litre oil container is convenient. Not switching during the tapping prevents a lot of mess.

An vacuum oil pump is required for an oil change and there is one included with the engine. I prefer a small (1.5 ltr) hand pump, 1.5 meters of drain hose makes it easy to use. Another handy thing is a rectangular funnel, remove the filter for topping up oil.

  1. First warm up the engine, about 5 minutes, hand warm on the oil filter (30-40 C);
  2. Remove the dipstick, put in the drain hose. If you put the hose in too far, it will curl up internally. Loosen the top-up cap to make it easier for the oil to flow back to the sump pan, lowest point;
  3. Pump off, take the last remnant with you by moving the hose, dipstick back in the opening
  4. Unscrewing the oil filter is often too tight. I don’t have any special band clamp pliers but use an old screwdriver as leverage.
  5. Lubricate the rubber of the new filter with some old oil. It must slide when tightening, otherwise the rubber will shift or tear and you will have an oil leak. Date on the label, handy.
  6. Tighten by hand until the rubber touches the housing. Then another 3/4 turn. Hand tight.
  7. Top up the oil with the right kind and then that rectangular funnel is a world invention after all.


V-belts are often placed behind a protective housing. Screw it off. Check the V-belt for damage and check the tension. Tightening a V-belt is done by moving the alternator further out. Nowadays there is often also an adjusting bolt that moves the alternator outwards. And then secure it properly.

Engine Maintenance - V-belt
Engine Maintenance – V-belt

Fuel Filters

Fuel filters, replace the filters with a new one every 250 hours. Always replace filter and o-ring. Close the fuel cock. First loosen the bleed screw slightly, then loosen the ring of the filter housing. Always take a look at the filter, the remainder in the filter housing. Wet the contact side at the top of the new filter and the o-ring with a little diesel so that it slides when tightened. And don’t forget, you should always bleed after a filter change.


Impeller, check every 250 hours but certainly replace every 500 hours. Engine maintenance without checking the impeller is a missed opportunity. The impeller of the water pump circulates the cooling water. An overheated engine is often the source of all kinds of malfunctions and problems. With modern engines you have a closed cooling system with Long Life Coolant that is cooled by your cooling system. In that case, the salty cooling water will not enter your engine, nor will any broken pieces of the impeller.

Engine Maintenance - The impeller of the seawater pump
Engine Maintenance- The impeller always turns clockwise
  • Loosen the bolts on the housing, some housings have a mechanical seal, others a classic O-ring. Then always place a new one, grease with a little Vaseline
  • A small flashlight is your friend, checking the impeller for cracks, worn spots, discoloration, missing pieces etc. Check the housing and seal for wear. Also always replace.
  • Trick: make the impeller smaller with a small tie wrap before installing it. Grease with a dash of Vaseline.
  • If you have a closed cooling system, you sometimes have an second impeller!
  • Brush the water inlet on the outside clean, and that is best more often than annually.


  • Air filter, every 250 hours, remove the air filter cover and wash the filter with soapy water. If you where in a sandstorm and cleaned the entire boat, don’t forget to clean your air filter.
  • Drain the diesel tank to dispose of any sludge or water collected at the bottom. At least once a year, but if you don’t trust the quality of diesel, then more often, always before long passages.
  • Throttle cable and the cable to the clutch, little to maintain. They stretch a bit in the first year, then tighten it a bit. A Teflon-pray or even a little Vaseline keeps it a little greasy on the transition shaft, cable.
  • Electrical connections, check every 250 hours. Look out for light corrosion loose bolts, clamps, clamp connections that come loose or rust. I find contact spray easy and a nice product.

After 500 hours

  • Exhaust manifold, check for cracks and clean every 250 hours and the indication is to replace it with a new one every 500 hours.
  • LLC or Log Life Coolant for the closed cooling system, drain and replace every 2 years or 500 hours. Pay attention to different brands, species can react chemically with each other. Never mix, 30-60% LLC, the rest just water.

Preparations and circumnavigation of a Seawind 1260