impellar - water intake problem

Guys,

I dont know whats going on...every time i have something wrong with my boat it seems to be impossible to fix.

Engine started overheating. Took out impellar found missing several blades. Found ( i believe ) all the broken blades. Had two spare new impellars in the boat that were there when i bought it a year ago. Took off impellar housing..put in new impellar with no lubricant of any kind. Started boat...smoked from impellar housing. Took it back apart...impellar looked fine...put grease on tips and housing and re-inserted. No smoke but still overheats. Freinds came over and said i had the housing upside down and it was backwards. Turned it around. Boat worked...skiied two hours and was fine...then overheated on the way back home at 5mph.

Took it apart again...put in the second new impellar ( i year old in plastiv bag in glove box but never used )...still overheating. Primed it with gatden house...intermitantly works. Turned it over again...now wont pump water eithe way...upside right or upside down ( whichever way is right ...still cant tell ). Bought new thermostat and put in. Still overheats. Pull hose off top of impellar housing and its not pumping water. Wont pump water no mater which way i install the housing.

Can the housing be damaged? It appears to have a removable part inside the housing where it presses the blades tight..could that be bad? Could the old impellars have just been no good? I can turn the housing by hand and feel the friction of the impellar. I can take the hose off and see the impellar spinning...but no water. Checked the line all the way to the lake...no blockages. Can blow air from the intake hose where it attaches to the impellar and air blows out the bottom of the boat ( bubbles ).   I can suck on the hose from right where it attaches to the impellar housing and get water up through it all the way from the lake. Its clear....but the impellar does not pump water. Is it the housing? Th inner housing replacable piece? Could the old impellars just be bad? Could having them the housing backwards have ruined the impellars? Im at a loss. Any help is appreciated. Also if you could tell me how to tell if the housing is in upside right or upside down. Boat is 96 nautique with GT-40 ford 351 engine.

We had a similar problem with our 1982 barefoot nautique. Engine is overheating with a new impellar in place. We arrived at the conclusion that the pump is sucking in air via a leak in the rear of the water pump. With no seal the engine will suck in air a before it sucks in water. I would check to see if the water pump housing is 100% water tight. Unfortunately, we have to purchase a whole new water pump. Hopefully this helps.