Flathead Engine Storage

Fech

Member
Hello, could you please advise on the best way to prevent rust in the original 1939 flathead engine during long-term storage?

Should I drain the cooling system completely, or is it better to leave coolant in the engine? If coolant should be used, what type do you recommend?

The local climate is mild, with spring-like temperatures most of the year and only a few months of low humidity.
 
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Install a coolant that has rust inhibitor in it and change it about every 3 or 4 years (its effect wains after a while). I use Preston. It also has a di-elect additive in it which is a benefit to deter metallic corrosion if there are different metals in your cooling system. If you simply drain your coolant out and you do have a sprit of freezing temps, you run the risk that there are pockets of ineffective coolant left in the engine which may freeze and cause damage.
 
Thank you for your response. The temperature here never drops below 32°F, so freezing is not a concern. Is it okay to simply drain the coolant and leave the cooling system empty?
 
I think there’s more chance of rust without the rust inhibitor in the anti-freeze. A little oil in the spark plug holes and turn it over very slowly a couple times before you put the plugs back in. Drain the fuel out of everything………Mark
 
I use this, spray in each cylinder and thru dipstick hole, rotate the motor a few turns, do once a year.
 

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... rotate the motor a few turns, do once a year.

I've done the this too. I would rotate with a wrench to a new point in the firing order every three months or so. I had a piece of paper and the date along with the 90° rotation ending position. My thoughts on this were to along with insuring free movement, were to have the valve train springs in a new state of compression.
 
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