Thermostat water port is blocked

[tfishingnut]

I have a 1975 25 horse johnson outboard and finally decided to check the thermostat after many years of owning it, only to find out that the previous owner took it out. My concern is there is a plastic plug in what appears to be a port for water. Should I remove this before installing thermostat

 

[Bosunsmate]

Re: Thermostat water port is blocked

Whats the inside of the lid look like?
Does it actually lead anywhere that hole?

 

[tfishingnut]

Re: Thermostat water port is blocked

It has a raised surface that mates with the gasket of the thermostat and two channels cut into that surface, one which lines up with the plastic plug and one 90 degrees from that. Sorry I have no picture of that right now but will post one later if you need it. It does appear to be there for a reason but was just not sure if it was something optional or what since I have no clue as to how a thermostat on a boat works to maintain water temperature. I am assuming that the previous owner put it there when he left thermostat out, just not sure why and do I need to take it out if I put thermostat back in

 

[Will Bark]

Re: Thermostat water port is blocked

Someone else will chime in but that could possibly be the pressure relief valve and would be part of the thermostat assembly. Don't take it out just yet.

 

[boobie]

Re: Thermostat water port is blocked

Back in those years the plug was put in to get the motor temp up due to plug fowling. There was an OMC service bulletin on it.

 

[boobie]

Re: Thermostat water port is blocked

I sent you a PM.

 

[F_R]

Re: Thermostat water port is blocked

boobie, that plug is news to me. Maybe we didn't have the problem here in FL? Well, we did too, but there were other reasons besides that. Can you share the bulletin?

 

[boobie]

Re: Thermostat water port is blocked

I've got bulletins going back to the prior 80's and looked today and I'll be damned if I can find it. I did do some motors up in Northern WI and it was supposed to be for plug fouling. I'll keep looking 'cause now it's got me bugged too. What were the other reasons ??

 

[tfishingnut]

Re: Thermostat water port is blocked

I was just wondering, if that hole is plugged and the thermostat is not open, is there any water cooling the engine before the thermostat opens?