Boat Diesel – Cooling water leaks

A leaking water pipe can often be temporarily repaired by wrapping the hole or split first in several layers of tape – ordinary electrical will do – and putting a hose clamp round the ‘bodge’ as a get-you-home measure. Ideally a spare, correctly-angled hose should be carried, or a length of reinforced hose cut over-long to avoid kinking.

Water leaking from a hose or fitting over the engine can cause extensive long-term damage and soon affect the operation of electrical equipment. Very little electrical equipment fitted to engines is truly waterproof and terminals are especially vulnerable to corrosion and failure.

To make matters worse, drive belts tend to pick up the water from any leaks and throw it liberally over the engine compartment.

If you see signs of a leak, first try tightening the fittings. If a hose has failed, replace it. Or, if you don’t carry a spare, patch it up as best you can for the time being until a replacement can be obtained.

Always take special care with any fittings sealed with low-friction PTFE tape. They can easily be overtightened, and perhaps cracked. As an alternative use a jointing compound or face seal. It is also difficult to remove PTFE from female threads, and tiny amounts can be scraped off when the fitting is tightened. PTFE debris then circulates in the water system and may block an orifice – often in the thermostat.

The filler cap on fresh water cooling systems should be removed and the water level checked when the engine is cold. It should be just below the neck of the cap. There is invariably some water loss after the header tank is initially filled up as the engine reaches working temperature. After a few checks the normal cold level can be established. If the header tank needs frequent topping up to maintain this level there is a leak in the system, which should be traced and remedied.

Leave a Reply

Your email address will not be published. Required fields are marked *