THE MOST common mistake folks make with the B 7100 is thinking they have a water pump. The device located where most engines have a water pump is actually the dynamo . The B7100 depends on the heat of the water to provide engine circulation and cooling ,absolutely imperative that the radiator is kept clean all the time including the lower corners. Most B 7100 failures are for overheating due to clogged radiator air flow not water otherwise outside not inside.
Jerry Watkins