Generic Question Regarding Thermostat Housings

[jon_allen]

Hi Guys,
I have a generic question regarding thermostat housings that have the spring loaded balls inside of them. What is the purpose of these balls and how do they work? Also what symptoms are present when they fail?







Thanks in Advance,
Jon Allen

 

[makomark]

If you are referring to a raw water system, the topic is the famous Poppet Balls!

The easiest way to describe their purpose is they provide variable resistance to the cooling water flow as it exists the system. At idle and low speed/low loads, the springs keep the balls mostly closed. This limits the water leaving the block so that the block stays full and no hot spots develop (and a few other things, too). At wide open throttle, they are mostly open and are really not necessary as the water pump has 'excess' capacity.

Symptoms depend upon the failure mechanism(s) in play...generally there are cooling issues and they can run the whole gamut.