Trouble-Free Running

Despite relatively calm weather around the North Island of New Zealand last summer holidays, the Northern Region Coastguard experienced one of its busiest periods ever, and basic engine maintenance could have prevented many of the distress calls.

A lot of the call outs (often caused by a breakdown at an inappropriate time which may put the lives of those on board at risk) could have been avoided if the boat owners' had undertaken what I call basic and preventive maintenance on their power plants.

Regardless of its size, the mechanical machinery in your vessel requires basic preventative maintenance to keep it in optimum running order. This goes beyond checking the oil and water levels in the engine. Modern diesel and petrol engines are sophisticated pieces of engineering that work in a harsh salt water and air environment - so they require appropriate servicing.

FUEL SYSTEM
A good fuel system begins with having a high quality primary filter/water separation filter. The clearances of a fuel injection system are minute and any particles or water will rapidly destroy the most expensive components in the high pressure injection pump and injectors often leading to internal engine damage if not corrected early.

From experience I have found that a basic primary fuel/water separator unit is not adequate. A couple of years ago my own charter vessel took on 200lt of contaminated diesel from an Auckland marina in the port fuel tank only. The skipper had done all his pre-checks prior to starting the engines and motoring over to the fuelling jetty. The fuel was taken onboard and the vessel proceeded down to the bottom end of Waiheki Island and returned later back to its marina berth.

A few days later, I did all the engine room pre-checks prior to a three-day charter and found to my horror that the primary fuel filters for the port engine and one of the gensets (fuel feed from port fuel tank) were completely full of water. Further checking found the port main engine secondary fuel filter was more than half full of water.

Nearly $5000 later (after the injectors for the main engine and genset had been renewed, and the fuel tank emptied and cleaned out) the vessel was ready for its three-day charter. Luckily, no other engine damage was sustained. This was an expensive lesson for me, as over a 16-year period and 5000 hours running I had never had any symptoms of fuel contamination.

The fuel system has been upgraded to a level that now includes a more efficient Racor fuel/water separator filter along with vacuum gauges that tell you when your filters need changing and, more importantly, a water level alarm system that lights up and audio alarms at the helm station if the water level in the filter passes a set level.

This setup now gives me peace of mind that any future water contamination will be found long before any damage can be done to the engines. Check your fuel filters for blocking and water contamination regularly, and change them as (when) recommended by your engine supplier.

SALTWATER PUMP
Another critical part of your engine, it pumps saltwater through the heat exchanger where the saltwater cools the fresh water that circulates throughout the engine, keeping it to its thermostatically controlled operating temperature. On the way out from the heat exchanger it might also cool the gearbox oil, refrigeration system and the exhaust system.

Most saltwater pumps are of the Jabsco type, either belt or gear driven off the engine accessory outlet. They are simple pumps with a rubber impellor that must never be run with the saltwater supply turned off. On my own vessel I have had up to 2500 engine hours out of an impeller so I now check the impellers annually (by removing the pump front plate) and I change them at 2000 hours if no sign of breaking or wear is found at earlier checks.

If in doubt, change the impeller (the cost of a new impeller and fitting is minor compared to the damage to an overheated and seized engine). Belts on belt-driven saltwater pumps (along with alternator and freshwater pump belts) should be checked regularly and replaced if any sign of wear is evident.

Before the saltwater pump you should have a saltwater strainer. Ensure it's kept clean, as a blocked strainer will reduce the saltwater supply, causing a vacuum on the intake side and leading to premature impeller failure and engine overheating. The air cleaner on marine engines is often overlooked. I've heard people say that as the vessel operates in a dust-free environment the air cleaner/element will not be getting blocked up. Nonsense! Dust and dirt get tramped into the carpets, and you'd be surprised at how much airbourne dust is around, even at sea.

My own vessel has vacuum gauges on the air filters so it is easy to see when they should be cleaned or if damaged, replaced. If not replaced a blocked air filter will starve the engine of air, making it run “rich” (in the case of a diesel, you'll see black smoke out of the exhaust). Again check, clean and replace on an annual basis if required.

COOLANT
The coolant in the heat exchanger must be checked regularly not only for the correct level but also the condition of the coolant. Straight water is no longer acceptable in any heat exchanger. The water must have the appropriate level of anti freeze/coolant conditioner for the engine to cool properly and stop corrosion of the block and liners.

Follow the engine manufacturer's recommendations and either check the coolant condition by using an appropriate coolant test kit or change regularly on the basis of years in service or engine hours done since the last change.

If not kept at the correct level of concentration, the piston liners can be eaten away to the extent where coolant can leak in the sump contaminating the engine oil. Never top up your coolant with straight water as this will reduce the coolant concentration. Always top up your coolant with pre-mixed coolant conditioner.

Most marine engines have zinc anodes fitted in the heat exchanger, saltwater pumps and oil coolers (if saltwater cooled). Regularly check these anodes for wear and, if worn to half their normal size, replace them. A new anode is cheap compared with replacing a heat exchanger core that has been destroyed by electrolysis.

BATTERIES
Without them your engine won't start and you're dead in the water. Check the electrolyte levels monthly (if they're not maintenance-free models) and, if possible, keep them fully charged up as this will increase their life span. When running, ensure that the battery voltage doesn't exceed 14.2V (for a 12V system) and 28.4V (for a 24V system). Too high a voltage will make a battery's 'gas' excessive and shorten its life expectancy.

Don't overlook the hydraulic gearbox - it's an essential part of the drive train. Regularly (at least weekly) check the oil level (some models require the engine to be idling when checking the oil level), and change the oil and filter (if fitted) as recommended by the gearbox supplier.

If all the above is done, you should have trouble-free boating and a relaxing cruise. While underway, monitor your oil pressures (engine and gearbox), temperatures and voltages. Generally, any changes should be picked up at the helm station. Personally, I make it a policy when on a voyage of more than one hour to go into the engine room and check for leaks, belts, and anything that might be out of place. It's surprising what you'll find when the engine is working rather than shut down.

All the best for 2007, and happy, safe boating.