Winterizing Inboard & Stern Drive Engines (Updated 05-28-06)

Old 10-06-03, 08:52 AM
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Arrow Winterizing Inboard & Stern Drive Engines (Updated 05-28-06)

Winterizing Inboards & Stern Drives

Well, the time has come to put your inboard boat away for this year. There are some things that need to be done at this time of the year to prepare your boat for storage for the winter months.

The first thing you need to do is to fill the gas tank, and add enough Stabil to condition the fuel for storage. After you top the fuel off, and add the stabil, you will want to hook up your water supply hose to your "ears" and attach them to the lower unit.

The "ears" I’m talking about are the same ones you would use to flush/run your outboard with. You need to use these to prevent damage to your engine, while warming it up.

Why are we warming the engine up you might ask, well we need to change the oil, and warm oil drains much easier than cold oil, and saves time as well, plus your pulling fuel into your carburetor with stabil in it.

Now your motor is warmed up to operating temperature. It is time to change the oil and filter. In your owners manual it will show you the location of where to pump out your oil. Most are through the dipstick pipe but there are some that have a special pipe just for this, so look in your owner’s manual to be sure.

If you don’t have a drill driven pump, you can get one from most hardware stores or farm and fleet stores. You need to make sure that your hose that runs down the pipe is well into the engine sump pan.

Once you have the oil pumped out, change the filter. There are several different absorbent mats that you can purchase to lay below the filter to catch any oil drippings. One thing I want to mention, and that is do not scrimp on engine oil or the filter.

Buy the best you can, as this will protect your investment. Make sure the oil filter has a check valve in it to protect your engine from oil draining back through the filter. Most inboards require 30-weight oil, some say you can use an alternative multi-grade, but make sure you look in your owner’s manual for the right oil for your engine.

Now that that is done, make sure your bilge area is clean, your right there, so you might as well clean it out if it is grimy. Make sure you start your engine and let it run a few minutes, then shut it off and wait a few minutes and check the oil and look for leaks around the filter. I also check the fuel filter/water separator, and look for any fuel leakage or oil leakage on any oil/fuel lines.

OK, so now the oil and filter is changed, we need to think about "fogging" the engine. First you want to pull the air cleaner/flame arrester, and start the engine again. Then as you increase the engine RPM’S to around 1500 RPM, hold it in this RPM zone, start pouring, or spraying the fogging oil into the carburetor until the engine slows down to about 1000 RPM, by doing this it insures that the maximum amount of oil has entered the combustion chamber.

It is important to coat the intake valves, cylinder walls and pistons from corrosion while it is in storage, and it helps to make sure your engine will not seize up while in storage. Once you see the white smoke coming out of the exhaust, continue pouring the fogging oil into the carb. And take the choke linkage and close the choke plate until the engine stalls, now your done with the fogging part of the engine.

Next we need to drain the water out of the block. To do this, check your owner’s manual for the location of the drain plugs or drain valves, whichever there are. I can tell you that on the in-line 4 and 6 Cylinder. engines there are 2 drains, one on the manifold, and one on the block.

On the V-6 and V-8 engines there are drains on both manifolds and in the blocks. Make sure you have located your drains using your owner’s manual, so you know for sure that you in fact have a drain plug, not something else.

Next we need to locate the main water line hose that runs from the water pump in the lower unit and runs up to the thermostat housing on the engine. You need to remove this hose from the thermostat housing. Now some of you don’t do this next step, because your book doesn't’t tell you to do this, but if you want more protection for your investment I would do this. You need to get some BAN-FROST2000 Marine Anti-freeze and mix it 50/50.

Next get a funnel and pour anti-freeze into the hose until it comes out of the water-up in the lower unit. By doing it this way you push out any water left in the line, and you also flush out the power steering cooler, and the water pump all in one shot.

Now you need to remove the two hoses at the exhaust manifolds that goes to the thermostat housing. After you do this you need to pour anti-freeze into the hose until it comes out of the manifolds drain, then tighten the drain plug, continue to fill the manifold with anti-freeze until it comes out of the prop, remember you need to do this to both sides.

Next you need to pull the large hose from the thermostat housing that hooks to the engine water pump. Fill this hose with anti-freeze until it comes out of the drain, tighten the drain plugs, and keep on filling until the block is full. Put the hose back on, and tighten the hose clamps.

After you have done this, if you have a shop vacuum, suck up any water/anti-freeze that may have spilled and any debris that may have entered the bilge area as well. I also would recommend spraying your engine down with WD 40 to prevent corrosion on exposed metals.

Well, we still have a ways to go, so on to the next step. We need to drain the lower unit oil. Make sure the lower unit is in the down position. Look in your manual for location of your drain plug or plugs and drain the oil from the unit. I cannot stress enough that you follow your manual for this procedure, by not doing it as your manual tells you will result in lower unit drive failure for certain!

If your lower unit is filled incorrectly an air pocket will form inside the drive housing, and when you turn the unit over in the spring you will have an air pocket on top and no oil to the bearings, and gears. If this happens you’ll spend a lot of money on repairs.

If you don’t feel comfortable doing this, have your dealer do it for you. It is not hard to do, but you need to make sure all the air is out of the lower unit. This is so very important, you must follow the procedure to the letter!

Now you need to put oil in the unit. Read your owners manual for your specific type. If you don’t need special oil, I would recommend using a synthetic oil or blend. As this has been prov-en to reduce bearing and gear wear, better than conventional oils.

I would recommend you get an inexpensive pump that fits into your oil bottle and you pump from the bottle with no mess. These pumps can be purchased from your local marine dealers which carry these pumps at certain times of the year, normally in spring. Marine dealers have them all the time.

Next, you want to take your batteries out. Don't leave them in your boat. After you take the batteries out, clean the battery storage area in your boat. If you take some cable ties, you can tie up your cables, label the wires, and make a very neat harness, instead of wires just hanging out to get broken.

OK, so you have the batteries out and you are wondering where to store them. If you have not done this before, all you need to do is to keep them in a dry place. The old myth that you can’t put them on a concrete floor is just that, a myth. I have found a product that really works in your battery to preserve the life of it and to keep it in new condition and, no corrosion anywhere.

All you need to do is to take out 2 oz. of battery fluid from each cell and replace it with Therm-oil, and refill to the proper level if it is still low. Make sure you use distilled water when bringing the water level back to normal. If you use Therm-oil in your battery you won’t have to worry ever again about corrosion. You can forget about checking water levels, because you won’t need to.

Next I will pull the wheel bearings, and the seals from the hubs. Before you reinstall the bearings, put in new seals in the hubs, don’t reuse the seals your just asking for trouble, and seals are not expensive.

Next I will clean the bearings with a recommended solvent never use gasoline as a replacement for a cleaning solvent. Than dry them off and inspect them for wear. I also look at the spindles to check for wear and pitting. If pitting has started, you can use emery cloth to take out the pits and smooth the surface.

If I see any amount of wear I replace the bearings and the races at the same time. Never put new bearings in and use the old races. Next I repack the bearings. I bought a bearing packer a long time ago at an auto supply store, and I don’t miss the mess of hand packing them.

Adjust the bearings as to the manufactures specs. And reinstall your bearing buddies if you use them. If you don’t have them I suggest you get some, as this is the best way to put grease in your hub for bearing protection and to keep the water out. Make sure you don’t over fill the hubs with grease as the hubs will run hot, you don’t want that, and you don’t want to pop the rear bearing seal either.

Just fill it until the spring-loaded surface comes to the front of the hub and a small amount of grease comes out. After you use your rig next spring, check your hubs again as I’m sure you will need to add some more grease.

Next check your winch rope or strap to make sure it is in good shape. Put a small amount of grease on the gear teeth, don’t gob it on; just a small amount is all that is needed. Put a small amount of grease on the tongue hitch mount as well. Check your rollers if you have them and make sure they are all in good condition. If you find a crack in one replace it.

Lower the motor to the run position for storage this will drain out any water left in it. Next I will take the prop off, check the splines, and put a light coating of grease on the spline before putting the prop back on. Make sure you check your prop for nicks and cracks. If it needs fixing, now is the time to get it done.

Next check mounting bolts, and any of your electronic cables such as your locator's and speed/temp cables to make sure they are connected securely to the boat.

I will also take out the drain plug and clean any water intake filters for the live wells, and reinstall. Make sure you blow out your live well drains, and bilge pump line, as water left in a line can freeze and you will have a real problem come fishing season.

Next I wash and wax the boat and trailer. I vacuum out the inside of the boat, including the live well, and I leave the live well covers open, and I clean the windshield with warm soap and water.

I also use a vinyl cleaner/conditioner on my seats and dash, and I remove the locator's and store them in a dry place. I also wipe down my trolling motors with WD40 and make sure they are unplugged. Some of you do not have this equipment. I check all my antennas and either fold them down or push them down and out of the way. I also make sure all drain plugs are pulled out.

So now we are ready to put the cover on the boat, but before you do this I recommend that you go to your boat dealer and get what is called mold and mildew bags, and put them in your boat. This will solve your problem of smell and extra cleaning in the spring. Make sure your cover is not torn and in good shape and that it has a snug fit.

Well that covers your winterizing! Now it’s a waiting game counting the days until the ice goes out. One last thing I want to mention, and that is your drive maintenance.

I would not recommend you attempt this service. Let the Pro’s do this at your dealer. Be sure to have the u-joints greased, the Gimbel bearings greased and checked.

Stern Drive Help & Info With Illustrations:

Marine Engine Flushing Informational Web Site:

DIY'S Boat Pages:

Regards, Good Luck & Safe Boating.
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Last edited by Sharp Advice; 10-06-06 at 10:48 AM. Reason: Updating Information

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