Water Pump Problems on 7.5

[mercurymark]

I have a 1975 7.5. At idle, I get a little water shooting out the tell tale hole and what appears to be some exhaust gas. When I rev it up a little, I get a good stream of water. It seems to me that somewhere the exhaust is overpowering the water pressure and that is causing the spurts I'm getting at idle. Then, when the speed is increased, the water pressure overcomes the exhaust and you get a steady stream. The question I have is where could the exhaust be getting to the cooling water? I changed the impeller last year and it does the same thing with a new impeller.

Any help would be appreciated.

 

[Harker]

Re: Water Pump Problems on 7.5

I think the only place exaust could get in would be through the powerhead to mid section gasket. Take a hose and spray up through the water tube while the lower unit is off and see if it blows anything out. Are you running in salt water? Could be deposits in the passgeways. It isn't hard to pop the powerhead off the midsection and replace that gasket and clean out the waterways. The other thing it could be is a poor seal of the watertube at the pump and it's only overcome with rpm's.

 

[mercurymark]

Re: Water Pump Problems on 7.5

Only fresh water. I'll try the hose and see what happens. As for the pump housing, I changed the rubber piece in the housing where the tube fits in. It was hard sledding, though. The rubber was really tight and the tube didn't seem to want to go in too badly.

 

[mercurymark]

Re: Water Pump Problems on 7.5

I dropped my lower unit and hooked the motor up to the hose. I got a GOOD stream out the tell tale hole, and also got a lot of water running out of the leg. Is that normal?