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During pre purchase test run, cooling water gradually stopped spewing from water exit hole.

Returned to Marina under fast idle power for 10 minutes in that condition. Engine did not over heat by touch.

Water pump impeller was found to have jumped the slotted shaft key allowing impeller to spin freely.

Need i be concerned that some other damage occurred during that operation?

Thanks.

Pete

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If you didn't get an overheat alarm, probably not. One thing to be aware of is if the impeller lost chunks, it very important that you find them, They can block water passages and cause damage that way.

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Thank you Duane.

I inspected the impeller myself and there were no "chunks" missing.

The impeller will be replaced.

I didn't know that there was an overheat warning. Good to know.

Thanks.

Pete

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Check that the tell tale, Exit hole, isn't clogged. I used a straightened paper clip to clean out the hole after getting into some mud. There was sand clogging the hole.

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Thank you, I did make sure the exit hole was open, remembering years ago that a mud wasp had clogged an outboard of mine.

Pete

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Impeller has been replaced by mechanic.

Not pumping as much water as I am used to seeing. Mechanic says this is normal due to the coldness of the Sea water, motor's temperature sensors are not calling for as much cooling.

Can this be?

Thanks,

Pete

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"Impeller has been replaced by mechanic.
Not pumping as much water as I am used to seeing. Mechanic says this is normal due to the coldness of the Sea water, motor's temperature sensors are not calling for as much cooling."

Pete, could be... The thermostats control the flow of water based on engine temperature. You mechanic could be right.

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Thank you Jon for that opinion supporting the mechanic's assertion.

It makes me a bit nervous not to see a steady stream coming out since I have never run a water cooled outboard that didn't throw a strong, steady stream of water, start up to shut down.

Could there be mud collected somewhere that keeps getting dislodged?

Thanks,

Pete

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"It makes me a bit nervous not to see a steady stream coming out since I have never run a water cooled outboard that didn't throw a strong, steady stream of water, start up to shut down."

I think your situation merits a little more investigation. You don't mention a specific engine, but to my knowledge, the tell tale stream is not affected that much by thermostat position or engine temp. You should see a steady stream regardless of engine or cooling water temp.

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What year and model 40 hp do you have? Something doesn't sound right. The impeller spins on a shaft based on engine rpm. The thermostat opens and closes to keep the engine at a constant temp. I'm not familiar with an engine whose water flow is based on cooling demands, but before I raise the BS flag, I need to know what it is.

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Pete, water should always be flowing out of the hole. It just may do so at different rates. Are you saying you see no water at all?

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Is this 40 an early 80s Evinrude? I had a similar problem on one where the tell tail was week a low RPM. The impeller came with 2 different size keys. And found the smaller key was used causing the impeller to spin on the shaft.

There should always be a strong tell tail, where it comes from is before it goes into the block or thermostat.

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Thank you all for your interest,

The motor is a 1998 40HP Mercury, 2 cycle.

Me and the mechanic went back to the issue yesterday, Sunday, he had me feel the thermostat, it was cool, about half strength stream of water coming from exit hole. We took it out and ran it and more water came out when we ran it hard but the strength of the stream lessened when we reduced throttle and they engine cooled. Mechanic insists this is normal with an engine with a thermostat in the cooling system. Gulf water temp is about 58 degrees.

Mechanic offered to change the thermostat if that would satisfy me.

The engine does not get hot. Stays a very nice warm feeling. Exit stream is not hot.

Mechanic did blow out, with air, the water exit hole to make sure nothing was obstructing that.

Pete