A technical failure at sea is among the worst things that can happen and the inconveniences due to defective cooling are among the most probable and most damaging. Prevening them is not difficult, just use the right precautions to ensure the proper functioning of the cooling circuit, the water pump and the impeller. And if – despite this – anyway a problem should happen, just have the right parts at hand to eliminate the problem and restart the boat. HPS is always by your side, both to help you prevent any problem, both to give you the necessary and most suitable spare parts, to go on the safe side and solve everything on the first blow.
The maintenance of the engine passes dutifully for the control of the cooling system, which in its essential lines consists of a water pump and a cooling circuit, with a thermostatic valve and one or more sensors for temperature control.
The peculiarity of marine engines consists in having the cooling circuit open; this means that it does not have a water tank, but takes the water necessary for its operation from the sea and returns it to the sea at the end of the cooling cycle. Unfortunately, the water of the sea or rivers has no characteristics to preserve the circuit, far from it: it can be sweet or salty, more or less calcareous, can contain harmful materials in suspension, such as sand, soil, aggressive substances, abrasive, etc. That is why the status and operation of the marine engine cooling system must be constantly monitored, with more attention and frequency than is the case with land-based engines.
The water pump is a mechanical pump driven by the movement of the transmission shaft. Opening the body of the water pump leads to the impeller, a sort of plastic/rubbery fan, which must be replaced periodically. The impeller is a particularly critical element and it is good to replace it in advance to prevent it from failing during navigation, causing major engine trouble. Its wear is easily visible by observing the cusps of the blades, which are visibly consumed during rotation. Also the state of the rubber is important; if it loses elasticity and shows an unhealthy appearance (eg with cracks) must be immediately replaced. At the same time, it is important to check the status of the metallic body of the pump (upper and lower), checking for any signs of abrasion and in any case carrying out their regular replacement.
The maintenance of the water pump and the impeller is not sufficient: it is necessary to also take care of the internal cooling circuit, which could risk clogging due to salt accumulations, limescale or other impurities of which the water you sail is unfortunately rich. To reduce this risk, it is advisable to wash the circuit frequently with fresh water, using the washing connector provided by the motor. It is a simple but essential operation: a few minutes are enough for a prevention that can eliminate serious risks.
There are some signs that warn you of the decay of the performance of the cooling system. For example, if the spy jet suddenly drops when the engine idles or if the temperature increases abnormally, especially at low revs, it is necessary to intervene immediately. But it would be better to prevent these symptoms from occurring, because the malfunction of the cooling circuit and the anomalous differences in temperature between the various parts of the engine, makes the thermal expansion uncomfortable and therefore greatly increases the risks of cracking and breaking in general.
The maintenance operations or replacement of the water pump and the impeller are simple, but it is absolutely advisable not to run them in navigation or in any case in water. The best time for such operations, especially for pleasure boats and in any case for those that in winter remain dry, is therefore the end of the storage, because in this way, in addition to having all the time to perform maintenance in the most corrected way, it prevents the new impeller from deforming or sticking to the pump during the months when the motor remains stationary.