New Thermostat Opening and Staying Open

[MotorlessCSJ16]

I just replaced all of the gaskets on my '98 Mercury 25 2 stroke, did a complete water pump job, and replaced the thermostat. In the process, I removed some corrosion from the powerhead at the thermostat housing bolt holes. I had to used a gasket maker in conjunction with the dry gasket to seal the water cover.

The motor is pumping water good but now it doesn't open and close like it used to. It is initially closed, opens, and stays open. I don't know why it's doing this now. It doesn't seem to be running hot but, then again, I haven't checked with a temp gun.

Any thoughts?

 

[Bifflefan]

Re: New Thermostat Opening and Staying Open

even new parts can fail.
exchange it for a different one where you bought it. recheck, and things shoud be good.

 

[MotorlessCSJ16]

Re: New Thermostat Opening and Staying Open

Just pulled it out and tested it in boiling water on the stove. Opened and closed fine. So part is probably good.

Any other thoughts?

 

[MotorlessCSJ16]

Re: New Thermostat Opening and Staying Open

Anyone?

 

[MotorlessCSJ16]

Re: New Thermostat Opening and Staying Open

Also, is it normal for the compression to fall fairly quickly when doing a compression test. It'll go up to 115 at 5 pulls and start falling when I go to look at it. I feel like I can't get an accurate reading when it falls this quick. Although, it is even compression on both cylinders.

Could it be a malfunctioning tester? Or something with the engine internals?