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Diesel Pre-Start Checks

Visual Check

Check belts and hoses for cuts, splits or fraying and look out for oil or coolant leaks.

Raw Water Filter

Shut the cooling water seacock, remove the filter element and clean it if necessary. Replace the element, screw the lid back onto the filter body and open the seacock.

Engine Oil Level

Check the engine oil level with the dipstick and top up if necessary to keep the level between the 'max' and 'min' marks.

Fuel Filter

Some boats have a transparent water separator/filter in the fuel line. Inspect the bowl for water or dirt and drain off any visible contamination.

Gearbox Oil Level

Check the gearbox oil level with the dipstick.
Some gearbox oil levels can only be checked with the engine running. Many gearboxes need special oil: engine oil will NOT do!

Fresh Water Level

Some engines have fresh water cooling systems as well as raw water. Carefully remove the header tank cap and top up with water/antifreeze mixture if necessary to bring the level within about 50mm of the top. Replace the header tank cap.

Bilge Blower

If you have a bilge blower or engine room extractor fan, run it for a few minutes before starting the engine.


Make sure you have enough fuel for your intended trip, plus a reserve of about 20% of the tank's capacity.
The fuel tap on a diesel system should normally be left open.
In twin-tank twin-engine systems, the fuel management valves should usually be arranged so that each engine is drawing from and returning to its own tank, with the balance pipe or transfer pipe valves shut.

Battery Switch

Turn the battery switch on before starting. Do not switch it off while the engine is running.