Exhaust in cooling system.
 

1999 150 Johnson 60 degree block

Noticed running temp a few degrees above normal. Checked thermostats for opening temperature. 1 opens @ 145 the other @ 148: good reading.

Before reinstalling them, I figured I would start the engine and see what kind of flow i have @ the thermostst holes. Upon initial firing, exhaust came out of the holes before seeing any water. Plenty of flow.

This test was done in a tank not on muffs, so there was exhaust back pressure. I've never done this before and with limited outboard mechanical expierence (except for this motor ) my knowledge of closed systems says this shouldn't happen. Is it different with an open system??

Blown headgasket(s).

Richard, one or more of the plugs will look like new if water
is getting into that cyclinder.
Simple compression test will tell you where you stand..

Concur with Frank on the blown head gasket..

Good luck...

Rich, when salt water enters the crankcase, things need to be spinning soon and for a good time. Heavy fog.

Thanks for the replies fellas. I forgot to post my own answer to the problem the other day. I found out that everything is ok except for a temp sending unit.

In the process of elimination I found the temp gauge sending unit to be off a little by borrowing a buddies thermal sensor or what ever its called. Nice tool to have.

I also found out that water and exhaust does mix at some point because water exits the exhaust idle relief ports as it always has; It would be nice for a confirmation on that Sandy. Go crank yours up and see if a little water comes out of those 2 holes beside the pee hole.

Thanks again for the replies...Richard

Water comes out the ports. First time I saw it freaked me out. Been thinking about replacing the head gasket o rings and " milling" the heads on some thick flat glass w/ 220. I am also concerned about the rubber t stat seats because they are a tad swollen and want them to open easily. What year is your motah Rich?

99. O-ring change is easy as long as head bolts don't cause problems. The old seats need to go

My list gets longer.