Hello all. The heater coil leaks so I bypassed it by going with a short 3/8 hose between the water pump and radiator and the water pump end of the hose leaks. Afraid of over tightening the clamp at the water pump end. Does someone sell a coupler to connect a 5/8 and 3/4 hoses or is there a way to stop the leak at the 5/8 end? Thanks for any replys.