Guide · Parts

Preparing a marine engine for the season

Before the season, inspect or replace the seawater pump impeller, the fuel filters and water separator, the oil and oil filter, the anodes and the belts, and check the cooling system and the engine mounts. Order parts a few weeks before launching, and keep a spare impeller and fuel filter cartridges on board.

Shipping: all of Croatia, islands included
Filters: Donaldson, Fleetguard, Racor
Warranty: 6 months

Preparation checklist

Part	What to do	Why
Seawater pump impeller	Remove and inspect, or replace; new cover gasket	Rubber ages even when the engine is idle. A cracked impeller means overheating.
Seawater intake strainer	Clean, check the cover gasket	A blocked strainer reduces the flow of cooling water.
Fuel filters and water separator (e.g. Racor)	Replace the cartridges, drain the water, bleed the system	Water and contaminants in the fuel damage the pump and injectors.
Engine oil and oil filter	Replace if not changed when laying up	Old oil contains acids and moisture.
Oil in the gearbox or Saildrive	Check the level and appearance, replace as the manual says	Milky oil means water is getting in.
Anodes	Inspect and replace worn ones	They protect the engine, shaft and propeller from corrosion.
Belts	Check condition and tension	A snapped belt stops the water pump or the alternator.
Cooling system	Coolant level and condition, hoses, hose clips, heat exchanger	Overheating is the most common cause of failure at sea.
Engine mounts	Inspect the rubber and bolts	Worn mounts transmit vibration to the gearbox and shaft.
Batteries	Charge, clean the terminals	Starting after the winter.

The scope and intervals for your engine are in the manufacturer's manual. The list is a reminder, not a substitute for the manual.

The impeller: the most important small part

The impeller is the rubber wheel in the seawater pump. When the vanes crack or take a permanent set, the water flow drops and the engine overheats. Pieces of a broken-up impeller can end up in the heat exchanger.

Many owners replace the impeller every season, regardless of condition. Check the interval in the manual.
When replacing it, find all the pieces that have come off the old impeller.
Keep a spare impeller with a cover gasket on board.
To order, send the engine model, or the pump model and number from the plate.

First start after the winter

Open the seawater valve.
Check the oil and coolant levels.
Start the engine and immediately check that water comes out of the exhaust.
If there is no water, stop the engine and check the valve, the intake strainer and the impeller.
Let the engine run and inspect for oil, fuel and water leaks.
Check that the gearbox works ahead and astern, at the mooring and with care.

Engine mounts and the gearbox

The engine mounts hold the engine and damp vibration. When the rubber cracks or separates from the metal, vibration goes to the gearbox, shaft and bearings. Good mounts protect the marine gearbox.

We offer mounts for Yanmar marine engines, for example for the JH and GM series and engines with Saildrive SD20, SD25, SD40 and SD50, and for other engines. For Twin Disc marine gearboxes we offer spare parts. See Engine mounts and Twin Disc.

What to order in good time

The impeller and the pump cover gasket.
Cartridges for the fuel filter and water separator, the oil filter, and the air filter if the engine has one.
Engine oil and gearbox oil. We offer oils from Fuchs, Shell, Mobil and Yamalube, and special oils for two-stroke marine Detroit Diesel engines.
Anodes for the engine, shaft and propeller.
The belt or belts.
Engine mounts, if they are worn.

Before the season everyone prepares their boats at the same time. Order a few weeks before launching, so that the parts arrive while there is still time to fit them.

Shipping to the islands

We ship parts and oils to your location across Croatia, islands included. With your enquiry, send the make, model and serial number of the engine (for example Yanmar, Volvo Penta, Deutz, Iveco-Aifo or Kohler) and a list of parts. If you need a repair, we will refer you to experienced service technicians. More about the programme on the Marine engines and equipment page.

Frequently asked questions

How often should the impeller on a marine engine be replaced?

The interval is in the engine manufacturer's manual, and many owners replace the impeller every season. Rubber ages even when the engine is not running, so keep a spare impeller on board.

How do I know the impeller is not working?

There is no water at the exhaust, or very little, and the engine temperature rises. Stop the engine and check the seawater valve, the intake strainer and the impeller.

When should anodes be replaced?

When they are worn, as the engine and drive manufacturer's manual says. Inspect them every season; very fast wear can point to a problem with the boat's electrical installation.

Do you deliver parts to the islands?

Yes, we ship parts and oils to your location across Croatia, islands included.

What should I send to order marine engine parts?

The make, model and serial number of the engine, and for the gearbox also the gearbox model. A photo of the plate and of the old part helps us confirm the part before shipping.