View Full Version : Anybody winterize their 7.4 Mercruiser with Bravo III?

King High Full Boat
10-25-2005, 06:06 PM
I know I have beat this topic to death :oops: but it seems there are several different ways to winterize? Do people recommend that you drain the block then pour the antifreeze into the hoses or that you run the engine and let the engine pull the antifreeze in through the lower unit?

I will say the Mercruiser book that came with the boat doesn't explain winterizing at all. :roll:

Thanks again for your help!


10-25-2005, 06:28 PM
This was posted on another forum, but I have always kept it around. Everything you ever wanted to know about winterizing but were afraid to ask [smilie=whip]

THIS IS NOT MINE< I stoled it [smilie=011.gif] :roll: [smilie=1074.gif]

WINTERIZING - the full way!
OK, i had a list of step by step things to do on winterizing a boat.....it got ruined when i spilled something on it and so i had to redo it best i could from memory.....This should be printed out for those wishing to do-it-your self. enjoy and please add comments if i have missed anything so we can all have a complete list. Granted some of these can be in different orders but this is how i do it most times and works great for me.

Winterizing Boat:

1. Add fuel stabilizer to recommended amounts for your size of tank. Top off tanks full to prevent condensation.

2. Lube all grease fittings ie. Tilt/Trim, steering, control cables, drive coupling, etc...

3. Clean and degrease engine and bilge area. (reason i do this now is that you can see if you have any leaks on a clean engine and the engine dries its self off when you run it later)

4. Inspect wiring, hoses, belts etc....for softening/cracking/bulging etc...and replace or repair as necessary to be ready for next season. Better to do this now then try and remember to do it in the spring when the fever hits!

5. Get the anti-freeze ready.....either premix the green automotive stuff of have the pink ready to go.

6. Run engine up to operating temps, and let it run for a little while longer to be sure to get the mixed sta-bil gas though the system.

7. Shut engine down and hook up the anti-freeze mixture. The quicker you do this step the less likely the engine will cool enough for the thermostat to close.

**NOTE** to be 100% safe you can also at this point drain the block and any other onboard options that are cooled by "lake water" ie. risers, power steering cooler, oil cooler etc to make sure that the anti-freeeze will get to all parts of the engine for complete coverage. But it does not have to be done if you feel the cooling system of the engine is working properly***

8. Start engine and switch over onto the anti-freeze mix...run till you have the anti-freeze mix coming out of exhaust thus knowing its has gone thorough the entire system.

9. At this point you can go one of two ways:
9a. You can spray the fogging spray down the throat of the engine while under idle till she chokes
9b. You can take the fuel/water filter off....drain about 1/2 out and fill it with 2cycle oil and put it back on...and run it till its smoking good.

10. Once engine stops or is smoking good shut it down and proceed to change oil. Here i just change oil and leave the oil filter on the engine (i figure since you will be changing oil again in the spring there's no need to waste a good oil filter) Have the new oil filter on hand and leave it in the boat with the new oil so you don't worry about that come spring time.

11. Changing the fuel filter/water separator now is also a good thing.

**OPTIONAL** Remove spark plugs and inspect. Spray some fogging oil into cylinders and turn engine over once with kill switches removed to coat cylinders. Again have new plugs onboard ready for spring time startup.

12. By now the engine compartment should be mostly dry from running the engine and is a good time for any touchup paint work that may be needed on engine or in bilge.

13. Spray a corrosion inhibitor on engine. (T-9 is a good one)

14. Drain any onboard tanks like fresh water, waste tank, shower etc and add the biodegradable anti-freeze. (DO NOT USE THE GREEN AUTOMOTIVE STUFF!!!)

15. also make sure to protect the AC system. Either blow out the water in the lines with compressed air or disconnect the line and run anti-freeze though it while the AC is turned on.

16. Move drive to the down position so not to stress the bellows boot or the shift cable boot.

17. Remove batteries and store in a cool dry place. Check water levels if not a sealed type battery and add if required. Clean and grease all battery connections to prevent corrosion. Cable ties can be used to group cables together to ensure proper hookup in the spring. Make sure all switches are off. Place batteries on a maintenance trickle charger.

18. Now is also a great time to change drive oil. Doing it now not only save you the time in the spring but the main purpose is to get any moisture out before it has a chance to start rusting the bearings in the outdrive. This time also gives you a chance to fix any problems you find over winter so you are not faced with a big expensive surprise come spring!!! Check all zinks mounted on either the drive or Gimbal housing and on Trim tabs.

19. Remove props, cover opening of drive with a garbage bag to keep rodents out.

20. If you have a fridge onboard, clean it out, disinfect, and prop door open for air circulation

21. Clean the interior of the boat and put a moisture absorbing or mildew fighting container/device. Bounce dryer sheets spread around the cockpit/cabin and possibly some rat/mouse poision in the cockpit of the boat to help ward off any unwanted guest's and have the boat smelling fresh.

22. Check all built in coolers, storage compartments, anchor lockers etc for any standing water that may freeze and remove.

23. Remove any electronics that are not permanently installed and store in a warm dry place.

24. Wash and wax boat. helps repel dust and dirt during storage and its nice to come back to a clean boat in the spring!

25. Now is also a good time for trailer maintenence. Inspect the trailer coupler and latch assembly. Inspect the saftey chains and fasteners. Check condition of trailer wiring, lights and bulbs. R&R winch strap/cable. Inspect rollers/bunks, nuts, bolts and hardware. tighten or replace as necessary.

26. If trailer is equiped with brakes check fluid level and top off. Good time to check pads and rotors/disks.

27. If you can....block the trailer and remove wheels and store on theirs sides to avoid flat spots. If not removing tires, fill to recomended air psi. (check the sidewall of tire for recomendations) Good idea to place some sort of cover on tires to help avoid UV damage from the suns rays.

28. Loosen the tie-down straps to reduce stress on hull

29. Leave the drain plug out and tilt boat up for any water that may collect to drain out. You can put the drain plug in a clear sandwhich bag and tie it to the steering wheel so not to loose it.

30. Check license plates for up to date registration and renew if needed.

31. Put cover on boat and make sure if you are in the snow belt that the cover can support any snow that may accumulate on it without ripping! Better yet place another plastic tarp over your boat cover.....this will keep stains from birds and leaves off the cover and will let you remove any snow buildup if outside more easily.

**NOTE** during winterization is also a good time to change the sea water pump impellor for good measure. This one $20 item can save you thousands in repairs from overheating if changed seasonally.

**Parts List***

-Fuel sta-bil enough for your size tank
-Heat or any fuel moisture absorber
-engine anti-freeze
-biodegradable anti-freeze for fresh water tanks
-grease gun with marine grease
-new oil enough for two oil changes and 1 fresh oil filter per engine
-New fuel/water filter per engine
-new sparkplugs per engine
-touchup paint
-T-9 or equivalent corrosion inhibitor spray
-mildew fighter and/or moisture absorber for interior of boat
-Bags to cover drives
-Any cleaning supplies for interior and or fridge etc...
-Bounce dryer sheets
-Rat/mouse poision
-Sea water pump impeller
-tire covers
-Tarp the size of boat
-Brake fluid for trailer (if so equiped)
-Misc electrical supplies for repairs
-2 stroke oil
-Holding tank deodorizer (head)
-Bowl and seal cleaner (head)
-Zinks if need replacement

10-25-2005, 09:43 PM
I do the first eleven steps.

I hook a bildge pump to a garden hose. Garden hose to the muffs. Stick the pump in a five gallon bucket which will be attended by another person. He hooks the pump to the battery and dumps extra anti freeze into the bucket. That person also tells me when the anitfreeze starts to come out of the exhaust. Then I dump the marval mystery oil to the fuel intake till it dies. Slow at first then more to kill it.