48 Cub

Sammy in Kansas · May 20, 2009

I have a 48 cub that I have owned for 8 years, and have used very little. I wanted to see about using it to mow yesterday, and it is using water. It looks as if it may be coming out of the overflow. Should this tractor have a pressure type cap or not. I am thinking the cap my be my problem, but have been told by some that it should be a presure cap and no by others. Please help me get the correct cap.

Lucien cyr · May 20, 2009

No pressure cap, The Cub 48 that I bougth 4 years add one on and I had to replace it with a non-pressure type.

ScottyHOMeY · May 20, 2009

Others can tell you for sure whether it takes a pressure cap or not.

What I'll add is that if you filled the radiator to the neck in preparation for running the tractor you should expect some overflow. It can be worse at first if you have any airpockets anywhere in the cooling system, as the air will expand more than the coolant as it warms and force coolant out. Can't hurt if you haven't already to run your Cub up a little bit of an incline to get any big bubbles up to the front of the motor and vented out the radiator.

Point is that the coolant will expand when heated and if you start with it absolutely full you will lose some. Perfectly acceptable as long as it settles down and finds its own level and stays there. That will usually be an inch or two below the bottom of the filler neck when cold.

Bigdog · May 20, 2009

A non-pressure cap is correct. The thermo-siphon system operates on temperature differential to circulate the water. There is a lot of water expansion with that system. It will spit out excess fluid until it reaches it's best operating level. As long as the tops of the core tubes are still covered when the system is cool you have plenty of fluid. The typical operating level is 1 1/2" or slightly more below the fill neck when cold. The water will expand to fill the space when hot. If you fill to the bottom of the neck when cold it will spit out lots of fluid for a while. I'd operate it and let it spit out the excess keeping an eye on the level for a while. Most likely it will spit out the excess and settle down to a level that just covers the core when cold.
A pressure cap will not affect this action but with an old system designed to operate with no pressure you may be asking for un-necessary pressure against old gasket surfaces.

48 Cub

Sammy in Kansas

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Lucien cyr

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ScottyHOMeY

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Bigdog

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