From the Atomic 4 FAQ’s
“... How should I prepare my Universal engine
for below freezing temperatures?
Boats sink on the first warm day of spring because the owner made 2 mistakes
at the same time. He/she failed to close the engine sea water
through-hull sea-cock when the boat was left for the winter, and water
was allowed to freeze in the sea-water side of the engine cooling
system, which ripped a section of the sea-water hose or cracked an engine cooling
system component. Once the ice melted it allowed sea-water to flow into the boat through the open valve and the damaged hose or component.
Remembering to close the sea-cock but failing to properly freeze-proof the engine will likely mean only massive engine damage and not a boat full of cold water too.
If you live in a place where there is any chance the temperature could go below freezing during the winter, you need to freeze-proof your engine before winter weather
arrives to make sure the engine and components are not damaged by freezing temperatures. There are 3 ways to ensure water can't freeze in the cooling system and crack or distort engine components. You can drain all the water out of the cooling system so there isn't any water to freeze, you can circulate antifreeze
through the cooling system so the water in it can't freeze, or you can use heaters to keep the engine and cooling water system warm enough so they don't freeze.
Draining: Even if drains can be opened without snapping off a seized drain plug
, they frequently are hard to get at, and they quite often get plugged up with bits of rust and dirt which stop the flow of water when they are being drained, giving the impression the component is empty when it is not. If water is not completely drained from every section of the cooling system it can cause freezing damage in one or more individual sections which may not be evident until years later when the component fails.
: The optimum solution for maximum engine antifreeze protection (good to -60C) is 60% ethylene glycol antifreeze and 40% water. In order to ensure an engine cooling system is properly protected the antifreeze solution must be cirulated to every part of the engine water jackets, heat exchanger
, water lock exhaust
or water jacketed exhaust
pipe, and sea-water intake valve, strainer, and hoses. Because it is possible for the antifreeze to reach only some of the engine water jackets unless the engine is fully warmed up and the thermostat has opened, it is necessary to rig up a system to recirculate the antifreeze solution through the engine while the engine is running while the engine grows hot enough for the thermostat to open, or to remove the thermostat before circulating the antifreeze.
Heaters: Heaters work well, as long as they are capable of maintaining the engine, engine coolant
hoses, exhaust system, and through-hull valve at a temperature higher than freezing, and as long as nobody pulls the plug
or causes a power failure. In latitudes north of Florida
using a light bulb for a heater is asking for trouble, since the light bulb doesn't put off enough heat to prevent freezing damage when temperatures start to go below -10 C. If a heater is going to be used, make sure it is connected to a temperature switch so it will turn on automatically when the temperature drops close to freezing, and that it can actually keep the engine and coolant/exhaust system warm. Ensure that the power supply is very reliable, and that a backup heater is available ...”
Here ➥ Atomic 4 Frequently Asked Questions
Don Moyer of Moyer Marine
is the A4 guhru. His website is full of useful information:
➥ Moyer Marine Atomic 4 Engine Rebuilding and Parts