By Phillip Harwick, Pamlico Diesel, LLC

The sailing season is just around the corner, but before you use your engine this year here are some steps that should be taken to insure reliability and full performance from your diesel engine and should apply to most gasoline inboards as well.

The first thing that needs to be checked is the cooling system. If the boat was properly winterized there should be no worry of freezing damage, if not then the cooling system should be pressure tested to ensure that no leaks have occurred as a result of freezing. There are two types of cooling systems, salt-water cooling and fresh-water cooling.

In salt-water cooling, salt water is allowed to enter the cooling passages in the engine block and cool the engine directly. In a salt-water cooling system that was properly winterized, the following items should be checked before using the engine this season:

1) Check raw water pump impeller for wear or broken vanes. If the impeller is on its second year, it should be replaced as most manufacturers recommend replacement after 1 or 2 years of service.

2) Check that the seawater strainer for the engine cooling is clean and that there is a basket or screen in place. If a strainer is not installed then one should be because dirt, debris and sea-life will plug up the vital cooling passages in your engine.

3) Check and/or replace zinc and anodes.

In fresh-water cooling, a heat exchanger is utilized to allow only a fresh-water and coolant mix to enter the engine blocks cooling passages. The heat exchanger transfers heat from the fresh-water system to a salt- water system much like a radiator transfers heat to air in a car. In the fresh-water cooled engine, salt water should never enter the engine. If it does, it is an indication that the heat exchanger may have failed internally. If, during your preseason check, you find the coolant level low or non-existent, this also may indicate a heat exchanger failure that should be fixed. In a fresh-water cooled engine, there are more checks that go along with the increased reliability that this system provides. Again if the engine was properly winterized, the following checks should be made before the season begins:

1) Check the engine coolant level. If there is any problem here, have the system checked with pressure testing equipment. If the level is fine then proceed to the next checks.

2) Check the seawater pump impeller for wear or damaged vanes. Like the salt-water cooled engines, if the impeller is on its second year, replace it. It is much easier now than cleaning little bits of impeller out of engines or heat exchangers after an impeller fails.

3) Remove end cover(s) or end cap(s) to the heat exchanger tube bundle and inspect the tube bundle for calcium deposits or plugging from debris. If you do not feel confident doing this, it usually doesn’t take very long for a professional to do this. This check will ensure that the engine will not suffer any overheating problems throughout the season.

4) If the coolant/antifreeze mix is two years old or more, replace it. As the fluid ages, it loses the chemicals that protect the metals inside the cooling passages from corrosion. The corrosion inhibits the performance of the cooling system allowing the engine to slowly overheat or create hotspots that accelerate wear. Replace with an extended-life product designed for diesel engines and you will be able to extend these replacement intervals to 3-5 years depending on the product.

5) Check seawater strainer to ensure that it is clean and that a basket or screen is installed. If no strainer is installed, install one. It will prevent dirt, debris and sea-life from plugging the tubes in your heat exchanger.

6) Check and/or replace zinc and anodes.

For All engines these checks should be made before beginning the season:

1) Check oil for water contamination. If any water is found, have the cooling system pressure tested. And the engine checked by a professional. If the oil is not contaminated but was not changed during winterization, it should be changed before returning the engine to service for the season. The engine will have to be warmed up to change the oil so leave this step for last.

2) Fuel filters should be changed before returning engine to service if they were not changed during winterization. Check primary filter/water separator for sludge or water. If any is found then drain. If problem persists or is severe then fuel tank(s) may need to be "polished" with a filter bank to eliminate water, algae and sludge.

3) Check batteries for correct electrolyte levels in all cells and that they are fully charged. If any batteries have cells that are dry or have plates exposed, they may have sulfated to a point that they will not accept/hold charge and must be replaced. If there are any other problems with batteries not holding current loading or accepting charge, they should be replaced. There are methods to reclaim batteries that have some sulfate damage but in a boat, reliability is more of an issue and such measures should be left to vehicles that can be parked if a failure occurs.

4) Lubricate control cables. There are kits available to introduce grease into cable assemblies. This is a maintenance item that should be performed regularly by the boat owner to extend the life of control cables and ensure ease-of-movement. Also lubricate all linkages and steering hardware at the same time.

5) Check marine gear/marine transmission oil level and quality. If oil appears discolored or otherwise contaminated or burned, then change it with oil that meets the manufacturers recommendations. If your drive is a "sail drive"(Yanmar, Volvo, etc.), then have the unit checked by a professional to ensure that all seals are intact. This should include a pressure test and vacuum test of sail drive unit while the boat is out of the water.

6) Check and adjust valve lash on engine. I have seen too many engines that this maintenance item is neglected on. Most manufacturers set intervals between 500 and 1000 hours but some are much smaller intervals. It cannot be done too often and does not take very long. This will ensure that valves do not "mushroom" their stems and that rocker arms do not "imprint" on the contact pads. On some engines with softer valve seat/valve head materials, not checking and adjusting valves will result in a burned valve or low compression as the valves wear. This is because lash clearance is actually taken up as these engines wear and valves will spend less and less time on their seats, where they transfer heat away from the valve head. After this check, reseal the valve cover(s) with a new gasket(s).

After these checks are made and all work performed, start the engine and warm to operating temperature. Do NOT use ether or any starting fluid. It will cause damage to pistons and compression rings although it may not be apparent for some time. Your engine should not smoke after starting and especially after warming. Some smoke upon start-up is normal for some engines but should dissipate quickly. If engine continues to smoke or run roughly/erratically then call a professional to troubleshoot/repair it.

After starting, make sure that there is adequate water flow from exhaust, all alarms are functioning, charging system is working properly, and all gauges are working properly.This should start you towards an enjoyable season with confidence that your engine is performing as well as it should. 

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If you have any questions about preparing your boat for the upcoming season or would like to discuss other issues with your engine further, please call Phillip at (252) 249-7223 or email at phillip@pamlicodiesel.com. For further information regarding Pamlico Diesel we invite you to visit their website at www.pamlicodiesel.com. Have a wonderful sailing season!