Water pump 92 100 GT

[Ma87k5]

I have a 1992 100 hp GT Johnson. The water pump isn't pumping like it should. I dropped the lower unit and checked the water pump. The impeller looks fine. So I thought maybe the pipe from pump to the squirter is clogged some where. I blew air from squirter and I didn't see anything come out. So I put water hose to pipe and the squirter squrited like it should. I also have about 1/8" holes on the starboard side of lower unit. I don't think the holes should be there. And thinking that the holes are taking away from the water pump pressure.

 

[Bosunsmate]

Re: Water pump 92 100 GT

Those holes could be just the drain holes.
Post a pic if you can.
Check the water pump housing for wear and that grommet 0320943 is on top of water pump.
Does it get better or worse with engine speed?

 

[Ma87k5]

Re: Water pump 92 100 GT

no change with engine speed. All parts are there.

 

[Bosunsmate]

Re: Water pump 92 100 GT

The top right and bottom left holes a normal
Hows it not running right? Not enough water pressure or inconsistent?
Overheating or is the telltale not flowing enough? Have you run some wire up telltale, they block extremely easily

 

[emdsapmgr]

Re: Water pump 92 100 GT

It's common for the telltale line/nozzle to plug with debris and not function normally. Esp if it's been used in shallow waters where the pump can suck up sand, mud. Once the engine is running, you can blow compressed air back up the telltale nozzle to clear it. Or just run some nylon string trimmer line up the nozzle and hose-to clear it.

 

[Ma87k5]

Re: Water pump 92 100 GT

I called the telltale the squirter. Using the water hose I put it up water pump line to the engine and the telltale pumped strong. Well I'm gonna put the lower unit back on and see if in fact there was something slowing the telltale. But When the engine was running with water hooked up to it. The telltale wasn't strong. It would spit to drip.

 

[Ma87k5]

Re: Water pump 92 100 GT

not enough water pressure.

 

[emdsapmgr]

Re: Water pump 92 100 GT

You've done a good comparison test on the telltale. Good thinking. Your tests should show strong telltale from the garden hose test and also when the lower unit is installed. Something is not correct. You did not mention replacing the impeller.. Though the impellers on these OMC's may look good, they do take a set after many years. And their pumping capability slowly goes away. When was it last changed?

 

[Ma87k5]

Re: Water pump 92 100 GT

That is a good question. While I have it apart I might as well change the pump.

 

[Ma87k5]

Re: Water pump 92 100 GT

update. I took a chance and put the lower unit back on. Well there must of been a clog. The pump works fine. Thanks