Bleeding the engine

James Stevens, author of the Yachtmaster Handbook, spent 10 of his 23 years at the RYA as Training Manager and Yachtmaster Chief Examiner

The modern diesel engine in a car is serviced by a technician in a white coat with a laptop, plugged into the engine’s computer.

Fortunately older marine versions of the diesel engine can still be maintained by an amateur and many of the common problems can be fixed on board without workshop support.

One of these is bleeding the engine. You will need to do this if you have run out of fuel and refilled the tank, or replaced the secondary fuel filter – any time air has found its way into the fuel system.

You have to be able to identify the secondary fuel filter. If you are coming at this with no knowledge of diesels at all, just knowing which part of the engine you need to work on is a challenge, particularly at sea, so it’s worth looking at the manual beforehand. Only one spanner is required, but it needs to be the right size, or adjustable.

You’ll need to find and operate the manual lift pump and have kitchen roll ready when diesel starts bleeding at the valve

The bleed screw on top of the filter is loosened a little, the lift pump is worked until diesel seeps out, then the bleed screw is tightened again and the engine should start. The instructions don’t tell you that even the strongest sailors can feel queasy working with diesel at sea so have plenty of kitchen roll and a bucket handy. Try to avoid spills into the bilge. Latex gloves are useful and a good tip is to put a smear of Vick’s on your top lip to kill the smell.

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