bn cooling

if bn dont have water pump how does it stay cool to keep from frying motor hope some one con anser this for me i found one for sale cheap but dont know if i can run bellymower with it with out buning motor up

Thermosiphon system, works fine.
http://en.wikipedia.org/wiki/Thermosiphon

You can run a belly mower all day with one. Mine spent years spending whole days cultivating without overheating.

The system without the water pump is called a thermosiphon. Basic concept is this. As the coolant is heated in the water jacket around the sleeves and in the head it rises. At the same time the hot coolant in the radiator is cooled and, as it cools, it falls. The heating in the motor raises the hottest water to the top. The cooling going on in the radiator draws to the bottom. It's a natural circulation/convection. On a tractor that's been working hard, you wouldn't want to rest your hand on the upper tank of the radiator, but the lower tank will be warm but perfectly comfortable to the touch.

It's all aided by the fact that the radiator and fan suction of air across it are all over size for the heat the motor produces. I've cited many times here about being at the house on the farm listening to my BN out in the field. What cold be heard from the house was not the exhaust (apart from the governor grabbing every now and then) but the howl of the fan.

It's efficient enough that another common post around here is from folks who have temp gauges and think they don't work because they never move. They will move if you work the tractor hard for a while, but just running around and light work, it might take hours to budge the needle.

Bottom line, don't let the lack of a water pump worry you. It was made to work and work hard without one.

Hi the "B" has what is referred to as thermo siphoning this was common on many tractors of that era (John Deeres, Earthmaster, MH Pony) for a few. They cool very well if the radiator is clean there will be no cooling problem.
GB in MN