hi i have a 1978 50 hp mercury blueband thunderbolt ignition 4 cylinder have put new impeller on motor but will not pump water to engine cant let it run for long byt steam comes out of pee hole instead of water can you help thanks john

john jones, April 2009

It sounds like a crimped copper tube at adapter plate under p/head.
The salt slowly crushes the tube causing a major restriction of flow.
Check by removing lower unit put hose pipe on copper tube and see how much water goes thru system.
I have had them so bad that virtualy no water will pass.

Brian, May 2009