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Winterizing Your Boat Engines

If you’re a boat owner who lives in a region that experiences harsh winter weather, you know the importance of winterizing your boat engine. Even if you live in a more temperate climate that doesn’t often get hit with snow or freezing temperatures, that doesn’t mean you’re exempt from this preventive practice, as freeze damage can still occur.

You can protect your boat from cold winter temperatures by winterizing your diesel marine engine through this comprehensive step-by-step guide.

Winterizing a Diesel Marine Engine

Fall is finally here with winter following right behind. If you are planning to store your boat this winter, for less than 6 months, follow these short-term storage procedures to protect your engines.

1. Change the Oil 

To begin the winterization process, start by changing your oil. Drain the oil out of the sump, replace it with the appropriate diesel engine oil, and change the filters. Start your engine and operate it long enough to pump fresh oil throughout the engine, approximately five to ten minutes. 

Using the right type of oil and changing the oil and filter at the proper intervals helps prevent sticking piston rings, piston seizure, accelerated wear of the in-cylinder components, and bearings. Refer to the owner’s manual for the correct procedure, viscosity and amount.

2. Drain the Cooling Water 

Drain water and sediment from your fuel filter/water separator – and from the fuel tanks, if possible. Then, replace the filter. Removing the water from your engine prevents the liquid from expanding and damaging the engine when it freezes.

Consider using a biocide in the main fuel tanks to prevent the growth of bacteria. Follow the biocide manufacturer’s instructions carefully. Too much biocide can harm the fuel system.

3. Replace the Secondary Fuel Filter 

Remove and replace the secondary fuel filter on the engine. Switching out your boat’s fuel filter ensures that your fuel system remains clean, operational, and free of damage. When your secondary fuel filter is clean, it can catch any contaminants the primary filter may have missed. Be sure to replace it with a manufacturer-recommended fuel filter.

4. Fill the Fuel Tanks 

Top off the fuel tanks with clean, fresh diesel fuel. Use the priming pump to completely fill the primary fuel filter/water separator, secondary fuel filter, and fuel injection pump housing with clean-treated diesel fuel.

Keeping your fuel tank full during the winter prevents condensation from forming in the tank and causing the lines to freeze. A frozen fuel line will prevent the diesel from reaching your boat’s engine when you use it next, causing it to stall or preventing it from starting at all.

5. Take a Coolant Sample 

Check the freeze protection of the coolant mixture. A quick coolant sample can tell you how well your engine is protected against freezing temperatures and corrosion. If the results of your analysis indicate that your engine isn’t adequately protected due to contamination, improper pH, or glycol concentration, it’s time to replace it.

6. Check the Zinc Rods 

Your boat’s zinc rods are responsible for preventing the electrolyte currents in saltwater from corroding the engine by taking on the corrosion themselves. When zinc rods begin to rust, they protect the metal engine components, keeping them intact.

Check your engine zincs to prevent galvanic corrosion. Remove and inspect the zinc rods in the cooling system and replace them if necessary. It’s a good rule of thumb to replace them after they’re about halfway depleted.

7. Inspect the Pump Impeller 

Assessing your boat’s pump impeller is an important part of winterizing a diesel engine, as this component prevents the engine from overheating. Inspect the seawater pump impeller and replace the pump cover gasket and impeller if it shows signs of damage or excessive wear. At this time, also inspect the seawater pump drive belt for damage or wear. Replace the belt if necessary.

8. Replace Rubber Hoses 

Inspect and replace all rubber hoses as necessary. These hoses are essential for keeping your boat afloat. You’ll know it’s time for hose replacements when they show signs of wear such as cracking, crumbling, mushiness, or excessive hardness.

9. Change the Marine Gear Fluid and Filter 

It’s vital to ensure that your marine gear is functional and in good shape so that it can transmit power from the engine to the boat propeller. Start by changing the fluid and filter in your marine gear. Drain and fill the transmission with the appropriate oil. Do not overfill the gear.

10. Clean the Filter Element 

Clean the air cleaner filter element to ensure that it adequately purifies the air entering your boat’s diesel engine. Clean or replace the filter element as necessary. The crankcase breathers should also be cleaned at this time.

11. Clean the Engine

One of the most important parts of winterizing a diesel engine is cleaning the engine itself. Use an appropriate cleaning solvent to remove all oil and dirt from the engine. Be careful not to allow the solvent or water to enter the intake system through the air cleaner. Allow the engine to dry and touch up your engine and marine gear with paint as necessary.

Winterize Your Boat Engines at Gregory Poole Today

If you have any questions or need to purchase any oil, coolant, or filters, give us a call. We’d be happy to assist.

Service 252-504-2640 Parts 252-504-5104