Tractor Repair: kubota 28hp diesel, full radiator, water pump

Question
flow of antifreeze /water by water pump. should the flow be noticeable when you look into a full radiator?how do you test a water pump? thanks a bunch.

Answer
Hello,

  It's pretty hard to tell sometimes by looking into the radiator if the coolant is circulating or not.  It depends on the construction of the radiator, crossflow radiators seem to be a little easier to see the flow.  It also depends on how full the radiator is, if the radiator is clean inside, how hot the engine is, the engine speed, etc.  Every machine is different.  In some, you can see the coolant moving quite easily, and in others you can't.  If the engine is overheating, it can be assumed that the coolant is not circulating properly, or the air flow through the radiator is restricted.  There is no test for a water pump.  If the bearings in it are still good and it doesn't leak, the pump is OK.  However something that does control the circulation and that can be tested is the thermostat.  If someone had lots of spare time and had the desire to do so, the thermostat and a thermometer can be put in a container of water on a stove and heated to see if and at what temperature the thermostat opens.  Obviously this is for a do it yourselfer because of the time involved.  A repair shop would just replace the thermostat and not bother testing the old one because the labor cost to test it would be many times more than the cost of a new thermostat.  Our shop labor rate is $85 per hour and a thermostat costs about $10.

                              Arnie