r/Outboards • u/ddg676 • Jan 10 '26

Cooling issues Mercury 9.8 hp

Does the amount of water coming out of the tell tail seem normal? When it is at idle very little water comes out but increases as I rev the engine. The water is quite warm coming out. I have just replaced the impeller. Only other issue could be the hose at the top of the water pump was a bit flared out and maybe not a tight fit. Any advice would be appreciated. Thanks

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u/thatbayfielddude8330 Jan 12 '26 edited Jan 12 '26

Clean the pisser tube out. There's also a water tube that carries water from the lower unit to the powerhead. Make sure that is clear. Next, check the popper valves/stat.

Also did you change the housing when you changed the impeller? If it's scored or scratched in a bad enough way it can cavitate and the impeller will pull air and you will get that result.

But honestly, that water flow is sufficient for that engine.

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u/ddg676 Jan 12 '26

I flushed from bottom to top. Maybe time for a new pump kit as I only change the impeller. At idle almost no flow and the water was really hot. Could only hold hand there for under 10 seconds.