4.3 t-stat housing nylon balls

[Baylinerchuck]

1990 4.3 L LX D428255. I changed the thermostat tonight in my motor. The PO obviously never changed it as it still had the copper sleeve installed as opposed to the nylon replacement. I cleaned years of rust and slag from the housing. It took me about 2 hours to scrape away enough crud to properly seat the new o-ring, t-stat and sleeve. My question is, the starboard side nylon ball was completely seized in the housing. I had to use a punch to knock it out. I spent a considerable amount of time cleaning up the seats so it's free and working properly again. What purpose do they serve, and what are the ramifications of one side being stuck closed?

Thanks in advanced for building my knowledge base!

 

[72GT160]

Being stuck closed there will be no water flow to manifold. Purpose is to stop water from being pushed back.

 

[Baylinerchuck]

Interesting. Could that cause an overheat situation? Who knows how long the starboard side was stuck closed. Could there be any permanent damage? Pardon my ignorance as I try to come up to speed.