Re: Hey Zane

Posted by zane on February 09, 1999 at 16:58:16:

In Reply to: Hey Zane posted by Turf Boy on February 09, 1999 at 14:44:26:

Turf Boy: OK. Here's the scoop. The tractor was a '39 JD A. It did not have a water pump, but, as did all early JD A's and B's, depended on "Thermo-Syphon" circulation of the coolant through the engine block and radiator. In order for this system to work, the coolant must expand (become less dense) when heated (by the engine) so that it tends to rise and displace cooler material in the radiator. Circulation in the cooling system is thus obtained. Such expansion is characteristic of water. This system was used with many early IC engines, including automotive. It requires an appreciable elevation difference between the heat source (engine) and the heat sink (radiator). Also necessary is the use of a coolant which expands when heated (like water) to stimulate circulation. Common antifreeze (ethylene glycol) is NOT (I learned!) such a coolant. In my case, I had drained the cooling system and then added a gallon or so of antifreeze, followed by enough water to fill the system. The antifreeze entered the engine water jacket but, when the engine started to warm, did not create circulation. Not suspecting a problem, I was not watching the tractor as I should have been. The engine got hot, no--HOT! After realizing what I'd done, I let the system cool, then drained the system again. I allowed the antifreeze to mix with the water and put it back in the system. It worked OK after that.

I should add that the tractor was (is) a toy and I didn't work it hard at all. Undoubtedly, ethylene glycol does not expand on heating and thus impairs the cooling activity (circulation) of thermo syphon systems. I found out later that JD recommended draining of their TS cooling systems during cold weather, rather than the use of antifreeze. Now I know why!

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