Winterizing your Atomic 4

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  • Don Moyer
    • Oct 2004
    • 2823

    Winterizing your Atomic 4

    Here is a rather free paraphrasing of Chapter 9 (Winterizing) from our service and overhaul manual:

    Winterizing an Atomic 4 should not require more than an hour or so. A list of tools and materials is shown at the end of the procedures.


    Moisture-related damage and cracked castings caused by water freezing in water jackets are by far the biggest threats during winter lay-up. While the potential for cracked castings is rather easy to visualize, moisture related damage is somewhat less obvious.

    Moisture can lead to corrosion on points which will almost surely cause hard starting in the spring. Moisture also can condense out of the atmosphere within partially filled fuel tanks and cause corrosion in carburetors, pumps, fuel lines, etc. And, even more troublesome, moisture can corrode valve stems enough to cause sticking valves by the time winter has run its course.

    In areas where moisture is known to be excessive, it is sometimes necessary remove the plugs and turn the engine over on the starter while adding a bit more Marvel Mystery Oil (MMO) to the combustion chambers to prevent sticky valves in the spring.


    Step 1: Drain oil. Draining oil at this time will set you up for an easy spring startup, since you shouldn't have to drain oil again until next fall (unless you exceed the recommended oil change interval of 50 hours).

    NOTE: The next step assumes that there will always be approximately a quart of oil remaining above the intake of the oil pump after draining. If, as you are running the engine in step 2, oil pressure should drop from normal, add a second quart of Mystery oil.

    Step 2: Add one quart of Marvel Mystery Oil. Run engine for about a minute to circulate the MMO-rich mixture throughout the oil swept section of the engine. I followed this practice for years to prevent internal corrosion (mainly on bearing surfaces, cylinder bores, and valve stems) and to facilitate re-commissioning in the spring when you need only to add enough new oil to bring the level to the full mark. It will save some time if you can look ahead and set up to accomplish Step 1 of the cooling system section while running the engine in this step.

    NOTE: In the years since we originally wrote these procedures, some folks have expressed concern over the use of Marvel Mystery Oil (MMO) in the crankcase on a continuing basis. While we still see no downside to leaving up to a quart of MMO in the crankcase during the winterizing process, if an engine is used very little, following our procedure could result in a concentration of MMO in the crankcase (over several seasons) which could exceed "one quart per oil change" as listed in the instructions on the MMO container. In all cases, if oil pressure ever lowers below what has been normal for a particular engine, or if you suspect that you may have more than one quart of MMO in the crankcase, the oil (whatever the mixture) should be removed and the crankcase refilled with straight viscosity 30 weight detergent oil.


    Step 1: Check all filters, paying particular attention to sumps which can (and should) collect free water if any is present. If any water is discovered, I would definitely take the precaution of draining the bowl of the carburetor as well as the main jet passage. Any moisture in the carburetor will surely turn into a chalk-like muck by spring and cause all kinds of trouble throughout the next season.

    NOTE: It would be good to manually operate the fuel pump to refill the carburetor before trying to restart the engine so as to limit starter cranking. All mechanical pumps have a "U" shaped lever hinged below them for this purpose. If that lever feels completely free when you try to pump with it, it simply means that the engine stopped with the cam shaft already deflecting the diaphragm. All you have to do is run the starter for a fraction of a turn and you should then be able to manually operate the pump. If you have an electric fuel pump connected directly to the positive terminal of the coil, you can fill the carburetor by simply leaving the ignition switch on for a few seconds (maybe 10 or so) before attempting to start. If you have an electric fuel pump with an oil safety switch, there's no easy way to refill the carburetor except to bypass the oil safety switch electrically while the ignition switch is on.

    Step 2: Top off the fuel tank. Add Mystery Oil as usual and if you've had any moisture problems, you may consider one of the moisture inhibiting fuel additives on the market.


    Step 1: If you operate in salt water, draw in at least one 5 gallon bucket of fresh water through the "T" fitting (which you should have previously installed between the raw water intake and the intake to your engine driven water pump). When the hose cavitates as the bucket empties, race the engine slightly for a second or two to partially evacuate the block and, more importantly, the exhaust system. This few seconds of running, after the bucket empties, will leave less water behind within the engine to dilute the antifreeze when you draw it in later. If you've installed fresh water cooling, proceed to step three.

    Step 2: Remove the two drain plugs in the side of the block behind the starter and alternator, and the single plug in the rear of the exhaust/intake manifold. If crud has settled out behind any of these plugs, it's best to take a wire and open up the area behind the plug holes so as to reestablish drainage. Reinstall drain plugs.

    NOTE: In engines with raw water cooling, I always felt it necessary to remove the thermostat prior to step 3 and to temporarily squeeze off the bypass hose to the thermostat housing. This precaution insures that antifreeze has to flow through the block.

    Step 3: Draw at least one gallon of recreational type antifreeze in through the "T" fitting previously used to draw in fresh water, or until you see antifreeze come out the exhaust.

    Step 4: For early models with thermostat, I recommend drawing in one gallon of antifreeze with the thermostat installed so as to get antifreeze circulated throughout the block and manifold, and then a second gallon with the thermostat removed and re-circulating hose pinched off so as to force the antifreeze through the exhaust system.


    Step 1: When all other reasons for running the engine are past, remove all spark plugs. Put several "squirts" of Mystery Oil in each spark plug hole. Attempt to aim the Mystery Oil toward the center of the engine (away from the manifold side of the engine) as opposed to straight down from the spark plug holes, which would be toward the valves.

    Step 2: Start the engine and run for just a few seconds. The goal is to shut the engine off in time to let the valve stems coated with Mystery Oil. If you have any RV antifreeze left, you may want to draw it in at this time as in step 3 above. Some antifreeze will be pumped out during the several seconds of running in the final step of the procedure, but this loss of antifreeze won't have any negative impact, since any air left behind cannot freeze.

    Needed materials include:

    Two quarts of Marvel Mystery Oil.

    "Squirt" type of oil can (with Mystery Oil).

    Five-gallon bucket.

    Two gallons of recreational antifreeze.

    Several gallons of fuel, as necessary, to top off tank.

    Three 7/16" hex-headed brass 1/8" pipe plugs to replace whatever style of plugs were previously installed in water jackets.

    Normal hand tools plus a needle-nose vise grip (in case any of the drain plugs stick).

    Best regards,

    Don Moyer
  • slunga
    Frequent Contributor
    • Oct 2006
    • 9

    antifreeze in the block

    Is it possible to remove the rear block drain plug and the thermostat housing and pour antifreeze directly into the block until it comes out the plug and then retighten? Just a thought.


    • brakauskas
      Frequent Contributor
      • Oct 2007
      • 9

      Winterizing cooling system

      I have a 1977 Columbia 8.7 with a later A4. I have some questions on the steps for winterizing the colling system. I have a raw water system in which the past owners would just put the intake hose in a bucket and run antifreeze through the system. I notice that you have extra steps such as removing the drain plugs and and removing the thermostat. If these steps are bypassed what could happen to the engine? If the thermostat is not removed and drain plugs are also not removed will I have water in the block and risk a crack upon freezing?


      • tenders
        Afourian MVP
        • May 2007
        • 1452

        If the thermostat isn't removed, yes, unless you're sure it's wide open when the antifreeze goes through, it won't circulate in the engine -- it will go straight through the bypass.

        With a block properly full of antifreeze, I don't think the drain plugs are so critical. I've never removed mine.

        I engineered a special winterizing cap for jugs of antifreeze by mounting a barbed plastic nipple onto one. I install that on the raw water intake, screw a full jug of antifreeze onto it, tip the jug upside down, poke a hole into the bottom of the antifreeze with a marlinspike, and run it through the engine. This gives the antifreeze a little bit of a "head" so the pump doesn't have to lift it out of a bucket.


        • bputney
          Senior Member
          • May 2006
          • 21

          Winter layup without starting engine?

          Hi Don,

          I intend to follow your winter lay up procedures tomorrow morning on my boat, which is out of the water and on its cradle. In case we have trouble getting it started, how would your instructions be altered to accommodate that? Will the hand crank at the front of the engine suffice to “pull” the antifreeze through the engine?

          Brett Putney
          1964 Columbia Defender 29'


          • Chip Hindes
            Senior Member
            • Aug 2007
            • 59

            Probably, but why hand crank when you can crank with the starter?

            Pull the fuel line first so you don't keep pumping fuel and you can make it really easy by pulling the plugs.

            Limit your cranking to no more than about 30 seconds at a time to avoid overheating the starter & wiring or running the battery down too much. If you need to crank more, let everything cool down for five miniutes or so before cranking again.+
            Chip Hindes
            '74 Newport 30' S/V "Scarlett"


            • Augustman
              Frequent Contributor
              • Jan 2008
              • 7

              Winterizing Engine

              As an alternative to the formal winterizing process, I was wondering if anyone out there in warmer climes has simply put a light bulb in the engine compartment and started the engine once or twice a week and let it run to temperature. We live 5 minutes from where we intend to keep this boat (if we end up buying it) and thought this might be an easier and less labour intensive alternative.

              Is this too risky, or can this work?


              • Chip Hindes
                Senior Member
                • Aug 2007
                • 59

                Visiting your boat once or twice a week to start it is less labor intensive than winterizing it? Sure, if your winter lasts about two weeks. Seriously, for how long do you intend to do this and exactly how long do you think winterizing will take?

                Starting a motor frequently just to bring it to temperature without putting it under some load is about the worst thing you could do for it.

                I believe using a light bulb for heat is asking for trouble. It's a fire hazard and what happens when it burns out the day after you've visited your boat?

                How "modest" is your winter? West Marine (and others) have fan driven pancake dehumidifiers that you can leave on indefinitely, but they're not designed to put out a lot of heat and might not be enough if a cold snap hits. Personally, I wouldn't count on freeze protection without a real heater, controlled by a thermostat.
                Chip Hindes
                '74 Newport 30' S/V "Scarlett"


                • swokrams
                  Senior Member
                  • Dec 2007
                  • 112


                  Why is it bad to run an engine and not put a load on it? I do this.

                  I'm in Vriginia the winters aren't too cold (except maybe right now), so I keep the boat in the water. As soon as it hits 50 degress or higher, I take her out for a short spin. But sometimes I just run the engine.

                  I have sea water cooling. I use a T valve to suck up anti-freeze before I turn it off. I figure if I run the engine at least once a month and refill with anti-freeze all will be well. The rest of the boat is winterized and stays that way.

                  Any thoughts?



                  • MikeB.330
                    Senior Member
                    • Jun 2006
                    • 249

                    The engine will never get up to operating temp. with out load on it. Even with a load it will take 45 min-1hr. to be fully warmed up. The cooling side will warm (temp gauge will come up) up but the oil and the lower half will not. By running the engine for only a few minutes at the dock moisture is allowed to enter the crank case. Because it never gets hot enough to cook out the moisture it will condense inside the block. Moisture on the inside on an engine is never a good thing.

                    I once had an air cooled Ducati Motorcyle with a sight glass to check the oil level. after a week or so of short hops around town the sight glass woudl start to get milky. The oil was fine but there was moisture on the inside of the glass. If on the other hand I ran the engine for 1 hr. or more it would clear right up.

                    Drawing in cool and damp winter cabin air into the crankcase must be worse than the air my Duc sucked in.

                    there are other reason as well such as carbon build up on the pistons /valves
                    ect. but the oil would my issue.

                    you would be better off installing a block heater with a timer on it but like you say VA isn't too bad.



                    • Chip Hindes
                      Senior Member
                      • Aug 2007
                      • 59

                      Pretty much what Mike B said. The motor will come to temp more quickly and more evenly if you run at idle in neutral only until it runs smoothly with the choke off, then move out and run under low to moderate load until it comes to full temp. The only exception to this would be if, because of wind, current, traffic or whatever, you'll be forced to run full load, max RPM as soon as you drop the lines. In that case, warm it up fully first.

                      It never occured to me your boat was in the water. Makes a little more sense than before. You could put it in gear and run it against the lines to speed the warmup under load, but my personal feeling is if you're not going to run it for real, you'd be better off winterizing it and leaving it for the season.

                      Does the water your boat is floating in freeze? The motor will be at most only a few degrees colder than the water around the boat, so if not, antifreeze may not be required. In this case as well, one of those WM pancake dehumidifiers may be all you need, and they're pretty inexpensive. If the water around the boat does freeze, then you will need freeze protection; as I noted above I'd do the winterization and be done with it for the season, but if you insist you need to start it up frequently, I'd go for the block heater controlled by a thermostat rather than constantly blowing out and replacing antifreeze.
                      Chip Hindes
                      '74 Newport 30' S/V "Scarlett"


                      • Augustman
                        Frequent Contributor
                        • Jan 2008
                        • 7


                        It's not in the water yet, but here in SE Virginia, we keep 'em in the water year round pretty much. It is extremely rare for the water at the dock to freeze. Maybe in water too shallow for an Alberg 30, but generally that doesn't happen.

                        Some friends of ours that used to own an Alberg 30 with an Atomic 4, suggested an electric radiator heater in the cabin. You can tie it off so it doesn't tip over. And also, take the boat out for a motor spin when you can.

                        Since there are still opportunities to go boating here in the winter, it seems a hassle to winterize the boat over and over again with antifreeze every time you come back in.


                        • vabiker23518
                          Senior Member
                          • Feb 2007
                          • 78

                          I did

                          I keep my Columbia 8.3 at Queens Creek in Williamsburg. Just last week we had two sub freezing days (down to 18!). I'm glad I ran the anti-freeze (I have fresh water cooling so it was for the heat exchanger/exhaust) and keep a heavy duty light at the back of the engine. I think that cold snap could have been a disaster! It takes less than 2 minutes to run the antifreeze thru the heat exchanger and insurance I think!


                          • Mr. Close Reach
                            Senior Member
                            • Feb 2009
                            • 51

                            leaking antifreeze on winterized engine?

                            First post - BIG thanks to Bill and the whole knowledge base here as I get to know my A4.

                            The boatyard winterized the engine a few months ago, and when I stopped by the boat last week I noticed that there was a greenish color in the bilge water. I pulled off the engine cover sure enough there was antifreeze at the spark plugs and puddled under the engine. No evidence that the tube from the overflow resevoir had come loose/leaked etc.

                            The boat engine does have an MMI-installed freshwater cooling system.

                            Any thoughts? I'm guessing that the yard didn't bypass the thermostat, but not sure if I have a big problem or a little problem on my hands.

                            Photo attached.

                            Attached Files
                            1975 C&C 33
                            A4 with FWC


                            • rigspelt
                              Afourian MVP
                              • May 2008
                              • 1252

                              Could it just be spilled antifreeze that did not get cleaned up?
                              1974 C&C 27