Tinker

Engine Service

Engine Service — photo 1
Engine Service — photo 2
Engine Service — photo 3
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Annual service on the Yanmar 4JH2-TE: filters, oil, impeller, and all the checks that keep a sailboat diesel reliable.

Every year before the sailing season, Coelacanth's Yanmar 4JH2-TE gets a full service. It is a straightforward job if you have the right parts ready and follow a logical order. Here is the checklist we use.

Material

  • V-belts
  • Fuel filter / water separator Parker Racor S3208P
  • Fuel oil filter Yanmar
  • Oil filter Yanmar 129150-35170
  • Impeller Yanmar 29470-42532
  • Vaseline
  • Oil, about 5 litres (depending on your climate zone: 15W40 for northern Europe)
  • Diesel: 5 litre canister
  • Cooling fluid (e.g. red Yanmar engine coolant)
  • Diesel additive (e.g. Grotamar)

The service

First, check and set the tension of the V-belts for the alternator and the freshwater cooling circuit.

Then we change the filters and prime the fuel system. Place a salad bowl below the old Racor water separator and unscrew it. Fill the new filter with diesel from the canister and screw it in. Next, unscrew the engine-mounted secondary fuel filter, placing a rag underneath to catch any fuel. Fill the new filter with diesel as well. Prime the fuel line using the manual lever on the Feed pump.

Start the engine – it will often need several attempts because there is air in the fuel line. Rev up a bit with disengaged gear. Make sure water spits out of the exhaust. Then, let the engine run for about 15 minutes with engaged gear, this warms the oil for easier extraction. Then stop the engine.

Take out the oil dipstick and attach the oil extraction pump. Generate a vacuum in the pump to extract the old oil through the dipstick tube. Unscrew the old oil filter and screw in the new one. Fill in fresh oil and check the level with the dipstick.

To change the impeller, close the sea water intake seacock. Open the impeller pump cover and check the lid for wear. Make sure all old vanes are accounted for – a broken-off piece can lodge in the heat exchanger and restrict cooling flow. Grease the new impeller with Vaseline and insert it, pressing and turning simultaneously. Reattach the cover and open the seacock.

Additional checks

  • Inspect the exhaust mixing elbow for corrosion and clean it. A corroded elbow can let sea water back into the cylinders – one of the more expensive failures on a sailboat diesel.
  • Check the gearbox oil. It should look like honey; replace if it doesn't.
  • Check cable pulls running from throttle to gearbox.
  • Check the oil level of the drive shaft.
  • Check the cooling fluid in the closed circuit and refill if needed.
  • Check and clean the sea water strainer. In winter: fill the raw water circuit with antifreeze.
  • Bunker diesel and add additive to prevent diesel bug.