Winterize Your Boat Motor (Inboard / Outboard) | Easy Guide

How To Winterize Your Boat Motor ( ALL Types ) | Easy Guide

Last Updated on July 20, 2020 by Amit Abhishek

Winter is about to come and as an responsible boater you need to winterize your boat motor. Winterizing your boat means protecting your engine, accessories and equipment from freeze damage due to extreme cold. Your boat motor need special attention as if not winterized; condensation happens in fuel tank, gunk develop and cooling lines freeze or crack in winter.

Whether you have an inboard or outboard boat motor we need to prepare the engine and your boat for long period of disuse. We need to drain the fuel, flush the tanks, disconnect any electronic equipment’s and remove the battery. In event of doubt or confusion follow the instructions and procedure mentioned in the users manual.

You can start to winterize your boat motor by adding fuel stabilizer for the Gasoline engine or fuel biocide for diesel engines. This must be then followed by adding anti-freeze and spray of fogging oil into carburetor. The last thing we do is to change over the engine oil and inspect hoses, openings and exhaust system.

Before you finalize the process and make arrangements to store your boat for the winter; make sure you have flushed the system and drained the cooling water line. While you can pay ($200-300) to get things done professionally. You can simply follow the instructions below; to do it yourself and save some money in exchange.

How To Winterize Boat Motor ( Inboard Stern-drive Type )

The process to winterize your boat motor involves simple few steps; which once learned you will never have to ask someone for help or refer to the user manual or guide such as this. In fact, the whole process is simpler than most people think but in lack of self-trust or time, we usually prefer to get this done professionally.

1 ) Preparing Your Fuel Tanks As You Winterize Your Boat Motor

Moisture builds up inside tanks if not properly cared which leads to fouling of fuel oil during the course of time. Thus it is wise to fill up the tanks with fresh oil. A full tank leaves little to no space for moist air to enter and thus protects against unwanted consequences. If not filled moisture will enter into the tanks causing fouling of oil due to microbial formation; that leads to serious trouble for the engine.

Now based on the type of engine you need to buy fuel stabilizer for gasoline engines or fuel biocide for diesel engines. I would suggest using Fuel Ox Marine – Complete Fuel Treatment ( Check Price On Amazon ); as it works well for both gas and diesel engines. Being a military grade stabilizer it prevent buildup of water, carbon and microbe in oil for long period of time.

It allows your boat to sit idle for long period of time without worrying for the degradation of fuel oil. Follow the instruction marked on the back of container or your boat manual; for adding sufficient amount of stabilizer solution to your fuel tank. For example 1OZ of solution treats 80 gallons of diesel or gasoline.

While you are done with adding stabilizer to the fuel tank; do not forget to run your engine for a few minutes for the stabilized fuel to run into the lines, carburetor and fuel injectors.

Winterize your boat motor - fogging oil

2 ) Spraying Fogging Oil Into The Engine

If remained idle for too long metal corrode and chip’s off and later cause trouble with the engine when reused in next summer. So its important to spray fogging oil into the engine; basically cylinder, air intake or carburetor. Basically we can use any of the three to do the job but for better accuracy we do it all.

The fogging oil lubricates and protect the engine against corrosion by sticking to the cylinder wall and other engine surfaces. This act as a film that avoid direct contact in between the metal parts and moist air. Basically it will protect your engine from any damage during the winter when it sits idle.

Now to do this process you first need to access the carburetor by removing the flame arrester. You can equally do the job by removing the air intake filter. Start your engine with your boat muff’s on and rpm elevated slightly and maintain the speed. Now slowly spray fogging oil into the carburetor in form of short burst of spray.

Continue the process till dark smoke starts to appear of exhaust or the engine dye down of its own. To be double sure of the protection you might also considering repeating the process; with injecting fogging spray this time through the air intake filter. For the process i would suggest to use STA-BIL FOGGING OIL ( Check Its Price On Amazon ).

3 ) To Drain The Coolant And Adding Antifreeze

The last thing that you will want being a boat owner is to let water freeze into the cooling chamber and its lines. The water will expands not just to cause stress on the structure; but can also rapture or break into the pipelines. So adding antifreeze solution is considered one of the key aspect to winterize your boat motor.

To drain the coolant out of the engine we first disconnect or close the sea-cock while removing the hose pipe on the cylinder block, outside of raw water pump and riser / exhaust manifold. Before you drain the coolant of the engine flush the system for a minute or two with fresh water and then drain it in a bucket to later flush it out of the boat.

Now using a plunger pump or pouring directly into the hose pipe connecting the cylinder block; we need to add the antifreeze solution into the system. Flush any extra solution back to the bucket and reassemble the hose connection. Now repeat the process for the exhaust manifold and fill the lines with antifreeze solution.

This solution prevents any residual water in the lines to condensate or freeze. For safety reasons many owners also dismantle the propeller; and drain the cooling lines using the drain plug after completing adding the antifreeze. Do not forget your engine should be in near warm condition when you complete this process.

Recommended: Star Brite Non-Toxic Anti-Freeze ( Check Price On Amazon )

How To Winterize Your Boat Motor ( ALL Types ) | Easy Guide
Author: Potiy ( Via Wikimedia ) Year: 2010, License: CC BY-SA 3.0

4 ) Drain Or Changing The Engine Oil

It is important to drain off the old engine oil before you winterize your boat motor. Not just that gear case oil is also drained and replaced. This is done because the old dirty oil gets thicker as the time pass if kept idle; thus restricting normal startup of the engine in the next summer.

That is why most people just drain the oil and prefer to replenish it with the new one; only during the spring time inspection. But many including myself prefer to replenish it now; while your engine is still warm and can be done easily. To start open the drain plug under or below the engine or use a pump to suck out oil from the dipstick line.

Now allow the dirty oil to drain slowly for next 10 to 20 minutes. Now locate and replace the oil filter usually found on the lower side of the engine. Once done refill the engine oil back into the system using the oil fill, funnel and fresh new oil. Similarly we open the drain plug for the gear case to drain gear oil.

Now to replenish it with the new gear oil we recommend you to use “Star brite Lower Unit Gear Lube Kit” ( check price on amazon ); which came with a marine pump. To do it refill first open the vent on top of the stern drive and connect the pump outlet to the lower drain. Now using your hand pump in oil into the system till it starts to came out of the vent. Close the vent, remove the pump outlet and seal the lower drain.

5 ) Place Your Battery Under Tickle Charge

Do you know battery discharge on their own slowly overtime if not used? And if it become deep discharged its overall life decrease drastically; or even may never charge again. When you have an expensive battery on board no one want’s to be that happen each boating season. So its one of key thing to protect when your boat sits idle during winters.

So invest some money in tickle charger and connect your battery with it. Or you can also use it back home for other odd jobs and charge it regularly. No matter what method you choose make sure your battery is not deep discharged or kept idle for too long. This will help maintain your battery life saving you from unwanted investments.

How To Winterize Your Boat Motor

How To Winterize Your Boat Motor ( Outboard Type )

It requires a few steps to get your boat ready for the winter – While a majority of steps remain similar for both outboard and inboard motors. It’s the few steps and their procedure that set’s it apart from the steps followed for the inboard stern type engine. While winterizing your boat gets a little tricky for stern-drive; its rather simple and easy for outboard motors.

1 ) Flushing The Engines – Warming Up!

Flushing the engine means running it with muff on so as there is continues flow of water and the engine does not run dry. This complete process involves covering the water inlet with muff and connecting them with water supply. Make sure the water fall from the top when start; if the water does not came out from the upper exit port you need to find and rectify the cause.

Never try to run your boat motor dry or otherwise you will damage it. Keep on flushing the engine for 5 to 10minutes till the engine’s warm-up, and is ready to undergo winterization procedure. For the process maintain the engine rpm at the slightly elevated condition and remained unaltered during the process.

2 ) Add Fuel Stabilizer To Your Fuel Tanks

Yes, whether its an inboard or outboard boat motor we need to add fuel stabilizer to the fuel tanks; to protect it from future degradation or developing gunk during the time its kept idle. For the process i would suggest using the “Star brite EZ Store EZ Gas Storage AdditiveCheck Its Price on Amazon.

You need to add 1oz of stabilizer for each 5 gallons of gasoline fuel. It not just protect against fuel degradation but also avoid corrosion or condensation of moisture within the system. Once done run your engine with muff on for around 10 to 20 minutes to allow the fuel oil to circulate around the lines, go to carburetors and finally to the engine cylinder.

3 ) Fog The Carburetor Intake

Although most recommended modern EF-i outboard engines does not require adding fogging oil solution before long storage. These engines itself are made in such a way that; with just normal flow of advanced fuel stabilizer it can remain intact while the winter season. To fog first open the top cover and slowly spray the fogging oil solution into carburetor with the engine running.

Spray the solution on a short burst till the engine starts to emit smoky exhaust or die down on its own. The extra thing that is done in case of outboard engines is to remove the spark plugs. It is then sprayed into the cylinder though these ports while the flywheel is slowly rotated with the hands.

4 ) Inspection & Cleaning Operation

Proper inspection and cleaning is also key aspects to winterize your boat motor. Inspect major parts of your engine motor while spraying silicon anti corrosive spray over it. This will protect and prolong your engine life and physical condition while protecting against the environmental forces. You can use “Yamaha ACC-SLCNS-PR-AY Silicone Spray Protectant“; Check Price On Amazon!.

Inspect the parts for signs of corrosion and wipe them with a clean cloth using your hands. Also inspect for any signs of damage or cracks on propeller, shaft and the seals. Remove and inspect the condition of fuel filter and replace if required. Usually its best practice to change fuel filter with a new one each year.

5 ) Drain And Refill Engine + Gear Oil

Drain the engine oil out of the system by opening the drain plug on the bottom left side of the motor. Store that waste oil in a bucket and allow the oil to drain properly for next 5 minutes. Once drained close the drain and fill in the new oil using the funnel in the oil fill. Now much like the inboard motor drain the gear oil out of the system.

Once drained using a gear lube pump fill in the line with the gear oil till it starts to came out of the vent. Now leaving the outlet of the pump connected to the gear oil drain; close the vent and then slowly remove the pump outlet and secure the drain port. Once done run the engine for a few minutes to allow the engine oil to circulates within the system.

6 ) Drain The Cooling Lines And Store The Motor

The final step to winterize your boat motor is to drain the cooling lines and stores the motor in upright position. To drain the water remove the muff and disconnect water supply. Let the water to drain out through the suction ports while keeping the motor in upright position. Once the water stops to came down crank the engine using hand to drain further water.

Once done take a final look at the motor, put the top cover back in position and put a little polish on the boat exterior. Your boat is just being ready to store it for long term. Just make sure you remove the battery and try to move the throttle in once in a while to avoid getting it hard to move by the next summer.

Complete Checklist For Winterize Your Boat Motor

  1. To winterize your boat motor; first, place the boat on trailer with muffs on.
  2. Fill the fuel tank up to 80 to 90% of its total capacity.
  3. Add fuel stabilizer to the fuel tank and let your engine run for 10 to 20 minutes when you winterize your boat motor.
  4. Flush the engine with fresh water.
  5. Open the engine cover and inspect for any sign of damage, corrosion, or cracks.
  6. Add antifreeze solution to the coolant system and drain the excess coolant within.
  7. Change and replace the engine and gear oil.
  8. Remove not necessary instruments, accessories, and valuables from the boat.
  9. Apply fogging oil to the carburetor and the engine block.
  10. Spray silicon anti-corrosive spray on the engine parts.
  11. Remove the battery and put it on tickle charge somewhere safe at home.
  12. Dismantle propeller and apply grease on the propeller shaft
  13. Cover and store your boat.
  14. Relax! You have done with how to winterize your boat motor and its accessories.
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