Mercruiser 470

[9nman]

Update on overheating Problem.

Update on overheating Problem. Finally bit the bullet and pulled the outdrive apart to replace the raw water pump. All the bolts were easy except for the sacrificial anode bolt which somebody had replaced with a regular steel socket head bolt. Had to call in reinforcements to get it out because the socket head was stripped.When we got it apart the lower half of the waterpump housing had gotten real hot and melted in the center. Two of the impeller blades were broken.
After we got it all back together we hooked the water up and she pumped like a champ. Bob

 

[troym]

"Pumps are lubricated and cool

"Pumps are lubricated and cooled by the fluid they pump. For that to have happened, flow had to have been blocked at some point, either at the suction (inlet screens) or somewhere down the discharge path (the engine or heat exchanger).
Have you come through that part or the problem?
It's pretty common for the impeller to start falling apart after a couple seasons, but the overheating of the housing is a little curious."