tssteph

Is the water pump on the front of the engine a standard automotive water pump or is it a "$pecial" marine pump? mine is dripping from the weep hole under the bottom.

Thanks

Dennis Moore

It is special, it has a stainless steel backing plate and a brass impellor for corrosion protection. An automotive pump will have a stamped steel impellor and backing plate that will corrode very fast, even in fresh water.

Because a Mercruiser with a Bravo seawater pump will create as much as 30 pounds of water pressure in the cooling system (an automobile engine will only make 16 pounds maximum), the marine water pump needs to be assembled carefully with a high quality water seal. You can not purchase a low quality, rebuilt water pump and expect it to last long. The pump will start leaking prematurely out of the weep hole like yours is doing.
Dennis Moore

mopower

The circulating pump is on the front of the engine and it is "special" in that it has a stainless back plate and usually a cast impeller not a a stamped steel one.
You can usually get away with a few years in fresh water , but forget about salt water , an auto pump won't last any time at all.

tssteph

Thanks Dennis, for all I know the one on my motor is probably a automotive pump. What about eliminating it and using a crossover?

Brian

homan

If you don't have fresh water cooling you don't need the circulating pump get a crossover and you'llnever change a pump again

Dennis Moore

See if a magnet sticks to the backing plate. It may be stainless steel. If it is, remove the backing plate (new gaskets are available) and see if the impeller is stamped steel or cast brass. Easy to determine.
You really should use the pump along with the thermostat housing. A bypass to circulate the water through the engine before the thermostat opens is necessary. The bypass is the hose from the intake manifold to the water pump on a Big Block Chevy.
Dennis Moore

H2Xmark

crossovers are some work to get them set up right, most of the time the back two cylinders will run hot if not set up right with the right size bypass, I would buy a merc water pump and get the newest part # it is improved, has a 1 at the end of the number if I remember right