Waterpump 9.8 Mercury Outboard

[mklein@iowatelecom.net]

Hello, Today I am having trouble with my 9.8 Mercury Outobard. The last time we were out the waterpump quit. Last season it worked fine... I replaced the impeller, but it still is not pumping in my tank... I have taken it back out again. Everything looks ok... I have blown out all of the passage ways... I'm stumped...

 

[Winkfish]

Water pumps do go out, even after changing the impeller. Do you have a water pressure gauge? What does Mercury say about the frequency of changing the water pump?

 

[mklein@iowatelecom.net]

I have changed the impellers out on both my 7.5 and 9.8hp Mercury's. The 7.5 only has exhuast gases coming out of the tell/tale weep hole. So far I have made sure it was in deep water in a 55 gallon barrell. I can blow through the copper pipe both directions. I have straightened the copper pipe in order to help get more compression seal on the seals, wich only resulted in collaping the seal in the top of the water pump. The SS wear plates look good with no signs of grooving. I do get hot exhaust gasses through the tell/tale weep hole. I do have the proper sized impeller and the key is in place to drive it. Where is the exhaust gas coming from? What do I try next? Thanks! Mark

 

[Winkfish]

I understand from another outboard motor forum that for Mercury motors, the water from the pee hole actually goes through the top cylinder head, so it has already circulated through the engine. If there's no water coming out, and if the pee hole tube is clear, then you've got a restriction/problem somewhere internally.

Is it possible when you pulled the lower unit to change the impeller that the water pump hose wasn't put back quite right?

 

[Barnacle Bill]

For sure you have to make sure that when you put the lower unit portion of the shaft back on the upper portion of the shaft, you have to connect the rigid tube to the right hole, or the water from the pump will not circulate through the engine and properly go out the exhaust port. This is easy to forget if you don't do this a lot.