By: Grid Michal
I replaced the thermostat in my 1998 Mercury 75 hp outboard, and it has worked fine almost all season. It has had a firm, steady stream from the port all summer. Last trip out, the stream was not nearly as steady as it has been. I ran some fresh water through it when I got home, and it was the same as on the water. It is not a trickle or anything; it is just not what it was. Should I be concerned?
Since you indicated the stream is the same whether you’re in the water or force-feeding water under pressure, you should look for trash in the discharge hose or outlet pipe. If it’s totally clear, then replace the water-pump assembly (14 years is a long time). The installation of a factory water-pressure gauge should ease a lot of fear.