Thermostat Spring & Check Valve 40hp 'rude

[Intermediate Mariner]

Good Morning!

I am working on a 1962 Evinrude 40hp (M#35530).

Inside the thermostat chamber, below the thermostat, is a spring and plastic ball (check valve). What are you guy's thoughts on these... I hate to impede water flow - does anyone know what purpose these serve or if they are important?

Thanks!

Shawn T
Wichita, KS

 

[F_R]

Re: Thermostat Spring & Check Valve 40hp 'rude

Yes it is VERY important. People insist on throwing all that stuff overboard, then wonder why their motor won't pump water.

When the thermostat is closed, water pushes that ball off the seat and returns to the water pump for recirculation. This goes on till the 'stat opens, then the ball remains seated and water is discharged through the open 'stat.

Note that the discharged water goes into the exhaust housing. That also means that if something didn't prevent it, exhaust could backflow into the system and down to the water pump--killing the pumping action.

The spring/ball check valve prevents that.

 

[Intermediate Mariner]

Re: Thermostat Spring & Check Valve 40hp 'rude

Thanks FR,
You are the man!
Shawn