Re: 4.3 mercruiser water pump problem
Water is only circulated through the engine by the circulating pump.
The raw water pump just provides water (under slight pressure) to the T-stat housing to be added to that water that is already circulating when the t-stat opens.
If water is indeed NOT circulating through the engine (although I am not sure how you would know this), it would or could be due to a failed circulating pump (impeller rusted away) or the cast iron passages completely blocked with rust either in the pump itself or the mounting pads in front of the engine........In this case, actual water flow THROUGH the system, which ends up discharging out the risers, would be unaffected.
If the pump is not turning, it should be very obvious.
I had a circulating pump in a 98 Taurus fail from corrosion a year ago. The stamped metal impeller had corroded(from electrolysis) so completely, it looked like a saw blade!! It stopped moving coolant altogether.
I don't think this happens very often with marine water pumps. Maybe you have an automotive circulating pump on the engine. If your engine is a salt water engine you may have severe blockage in the water pump, heads and block too.....
Things to check!
regards,
Rick
