Thread: Still stumped with water pump

GOJO works good too

Thanks to all who are trying to help.
Tonight i went back through the steps.
Prop to pump rotation - good
Impeller vane position - good
Correct parts - good
Key in position - good

The impeller definitely getting hot. Steam comes from the telltale just before dying. When i removed the lower unit a small amount of water dripped out and the inside surfaces are wet and a tanish goo. Looks like contaminated oil. Thinking i might have a blockage in the cooling flow.

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A blocked intake or output is the only thing that makes sense.

I had a raw water cooled diesel, that the heat exchanger had slowly clogged with scale. I chased cooling issues and replaced multiple impellers, until I figured it out. It was a tough old engine.


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Originally Posted by silverside

Thanks to all who are trying to help.
Tonight i went back through the steps.
Prop to pump rotation - good
Impeller vane position - good
Correct parts - good
Key in position - good

The impeller definitely getting hot. Steam comes from the telltale just before dying. When i removed the lower unit a small amount of water dripped out and the inside surfaces are wet and a tanish goo. Looks like contaminated oil. Thinking i might have a blockage in the cooling flow.

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How are the water intakes? Good and clear? If you haven't, take the grates off and flush them out.

I'd think if there was a blockage the vanes would just deflect and bypass, not destroy themselves.

You running the engine on muffs or in a barrel?

The only reason you should lube the impeller is to ease installation, it will not burn up if you don't, they're designed to be lubed only by water. I've never lubed one and have no issues.

Might be a good idea to drop the lower unit in a bucket and spin the driveshaft with a drill, see what it does. If it pumps good without an issue, you know the problem is in the power head.

With the lower unit off, you can put compressed air through either the water tube or the pee hole, but to really flush it out good you may have to remove the thermostat.

I tried the 4th impeller today. Everything, did I mention everything, was correct. As always I tested it at one of the ramps near home. It worked as expected for a few minutes. No tell-tale flow while warming up. Then, after about 4-5 minutes steam came from tell-tale, motor overheated and shut down. I pulled the lower unit to find a completely unharmed impeller. I have blown air and water through the system and the flow is not obstructed. Next move is to remove the thermostat even though I tested it and it works fine. It seems as this dude is possessed

Maybe I missed it some where, what is year,make, hp, and 2 or 4 stroke. I'd like to pull up some diagrams and see if I can see anything.

Originally Posted by Cray

Maybe I missed it some where, what is year,make, hp, and 2 or 4 stroke. I'd like to pull up some diagrams and see if I can see anything.

It is a 1982 Merc 110 9.8 2 stroke. Very low hours on motor so im surprised at the trouble.

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Have looked at all the diagrams I found on this motor. Could find no thermostats. Check this diagram. Look at 7-8-10. Appears number 10 is some kind of bleed valve. If water flows through these lines to cool block that valve could be stuck not letting water flow. I'm sorry I can't be more help but just never worked on one and don't have one to put my hands on. I'm going to pm you a phone number to a local guy that is a merc guru and that's all he works on. Very nice guy and usually very helpful.