Mastercraft Winterization Procedure


Mastercraft Winterization is a process that requires immense care and utmost importance to avoid damage under any circumstances. If not dealt with earnestly, one may face difficulties while reactivating their boat. So make sure you follow the instructions carefully to complete the winterization process without any complications.

Treatment for Fuel System:

If you are storing the boat with alcohol-free fuel, begin with filling the fuel tank with fresh fuel and a sufficient amount of Sta-Bil gasoline stabilizer. However, if you will be storing it with fuel that contains alcohol, then it is necessary to drain the fuel tank entirely and add Sta-Bil gasoline stabilizer to any fuel left in the tank. Moving ahead, start the engine and bring it to normal operating temperature. Run the engine around for about 15-20 minutes so that the stabilizer enters the engine‚Äôs fuel system. Now carefully loosen the flame arrestor, just enough to insert the tube of the fogging oil can. After spraying 4-6 ounces into the carburetor, turn off the engine. Remember to reattach the flame arrestor and seal it using low tack tape. Now you can perform the annual maintenance. Don’t forget to loosen the accessory drive belts!

Keeping the flame arrestor intact:

It is advised not to operate the engine without the flame arrestor as it can increase the possibility of an explosion in the presence of gasoline. If however, the flame arrestor is not secured, and one must be extremely cautious and make sure that no leaks are present. It is vital to keep the engine compartment well ventilated when not in use to avoid any accidents.

Winterizing Process for all Engines:

Start by draining the exhaust manifolds. It is highly recommended by the manufacturers to leave the drain plugs out, and the hose uncoupled when the boat is being placed in storage. Next, remove the raw water pump hoses from the front of the engine and drain the remaining water. Now remove the raw water pump impeller from the pump housing. If it is already prone to wearing, discard it. Otherwise, you can lubricate it using soap and store it in an airtight bag. Lastly, remove the hose from the lower end of the transmission cooler and clean any dirt or debris present.

Specifics of Winterizing Raw Water-Cooled Engines:

To treat the raw-water-cooled engines, you have to remove the petcock and drain plug from the engine completely. It will be handy if you store the drain plug in a plastic bag and hang it over the steering wheel. That will remind you of reattaching it back in the spring. Now, use a piece of stiff wire to clean the drain hole and remove any rust from its surface. Finally, you have to disconnect the large diameter hose and drain the remaining water.

Specifics of Winterizing Fresh Water-Cooled Engines:

For fresh water-cooled engines, you have to begin the process by removing the water inlet and outlet hoses from the intake side of the heat exchanger. Next, you have to measure the strength of the coolant on the freshwater side of the heat exchanger by using a specially designed antifreeze tester along with propylene antifreeze. If the level of coolant in the heat exchanger is low, you must add a sufficient amount of coolant mixture to fill it.

Read the instructions on the container thoroughly and prepare the coolant mixture using the appropriate amounts of distilled water and propylene glycerol antifreeze. However, if the coolant is not strong enough to protect the engine from the lowest predictable temperature, then feel free to get the coolant replaced by the dealer.

Drive train preparation:

When winterizing the boat, it is essential to clean the filter screen and change the transmission fluid as it will keep the drivetrain well lubricated. One must remove the attaching hardware from the propeller, separate the flanges and grease the surface of drive train entirely to prevent any damage.

General Power Package Preparation:

These few steps are vital for the preparation of a general power package. Firstly, clean the painted surfaces of the engine, transmission, and drive train from any dirt or grease. Next use multi-purpose grease to lubricate the throttle, cables and shift linkages. Remember to spray the entire engine with a corrosion protectant. You must also remove the battery cables and the battery from the boat. Charge the battery and store it in a cool and dry place. Be extremely cautious and keep it away from any fire or explosives.

Basics on Outdoor Storage:

Start by attaching a hose to the starboard side ballast hose. Get a gallon of non-toxic RV type antifreeze and place the other end of the hose into it. Now turn the pump on to empty and fill the system with antifreeze until it comes out of the thru-hull side. Lastly, turn the pump on to fill and pump the antifreeze back into the container.

Basics on Outdoor Storage:

If the boat will be stored outside, it is important to secure it from the changes in weather e.g., rain, snow, and hail. For this, one must prepare support and cover it from the outside, so no damage is done to the body or internal engines. The most convenient way to solve this is by securing it with a two inch PVC plumbing pipe. Not only is it easy to work with, but also, is available at general hardware stores.

Essentials of Mastercraft Winterization:

Following are a few steps you must consider while winterizing your boat to prevent any damage:

  • After taking the boat out of the water, remember to remove the bilge drain plug. Also, to allow the maximum amount of water to drain from the bilge, raise the bow of the boat higher than the stern. This will surely do the trick.
  • It is easier to clean the boat right after you take it out of the water. But do leave it to air dry for a few days to prevent moisture from trapping within the interior.
  • If the boat is equipped with a heater or shower, make sure to drain the pipes as freezing in these areas can be damaging for the engine.
  • Seal the exhaust flaps using duct tapes to prevent the dirt from entering.
  • To prevent the V-belt and hose from getting damaged, ensure that they do not get tangled in the process.
  • Apply a generous coat of wax on the entire surface of the boat and cover it with a tarp or boat cover.
  • It is extremely important to get an oil change performed before the storage process to avoid damage to the engine.


If you follow all these instructions down to the dot, rest assured your Mastercraft winterization process will be as smooth as ever, and the results will exceed your expectations.