Johnson 15 hp 1975 blowing steam

[JoeK]

Outboard runs good and water c

Outboard runs good and water comes out the relief valve when running fast. When I throttle down though I get steam throught the relief valve at the back of the engine. Doesn't seem to overheat but lots of steam. When I take off again it starts spraying water gain.
Any ideas? Thanks in advance

 

[tommyg]

Its about time for a new water

Its about time for a new water pump...! Don't keep running it hot like that...steam means its to hot..!