I removed the check ball from my thermostat housing and found that there is no passageway from the ball's socket behind the ball into the water stream. It is my understanding that air trapped in the top of the block is supposed to flow past the check ball and when the air is gone and coolant tries to flow past the check ball the coolant lifts the ball and closes the port into the water stream. I dug around with a pick and cannot find any evidence of a clogged passageway behind the ball. It appears that the ball does nothing in the current situation. Am I wrong?

 

Should be a bhpass there some place...

 

its very common in large engines that when they are shut off hot, because the water pump is not moving, coolant through the system any more that coolant in some places will reach a point of temperature that produces steam bubbles and these bubbles need to reach the top tank of the rad to cool, this collection of bubbles displaces coolant, increasing pressure, forcing the rad cap to release so as not to expose hoses and radiator to high pressure, the check ball should just allow flow past the thermostat when the pump is not turning and or steam bubbles (that can't hold ball ) is present 1 gallon of water can produce 1,750 cubic feet of steam.

 

the passage is probably blocked with rust or scale I don't have a block handy to get a pic.

 

If there is enough heat to produce a steam pocket, the thermostat will still be open and you will get a small amount of convection induced flow. If you have an electric fan on a battery circuit instead of an ignition controlled circuit, it will cause a much higher convection flow and will cool off the shut down engine much more quickly then it would otherwise. Parking into the wind would give a similar effect.
To check the check ball passage, spray some carb clean down it with the can's straw. If it just shoots back at you then it's completely blocked.

 

Maybe I got my terminology wrong. The ball is trapped inside a cavity in the thermostat housing (water neck?) by a plastic ring. I assume air comes up through the hole in the block into the hole in the th/wn where the ball is. Is there supposed to be a hole in the cavity behind the ball that intersects the main water passageway in the th/wn- the passageway that the upper radiator hose connects to? If there's no hole there where does the air that comes out of the block go once it gets to the ball?

 

Yes, there is a hole ... Look in through where the hose connects and you can see it on a hump.

DO NOT drill a hole in the thermostat, it is about 2" to low, that is exactly why the housing is designed as it is, the current vent is at the top of the water jacket where the steam would build up.

EDIT
Remember to only use a Motorcraft E5TZ-8575-C or Navistar 1807974C94 thermostat.

-Enjoy
fh : )_~

 

OK, I just came into the house to get on the computer to report that I kept scratching around with a pick and awl and finally found the hole. It was completely clogged with rust but it is open now.

 

I had done that previously and it sprayed right back in my face. Passageway is now open.

 

Not to hijack this post but, how important is it to even have the ball in there? I've heard of people just removing it

 

With the ball removed there will be a continuous bypass around the thermostat. How much water can bypass through a 1/8" (maybe less) hole? Obviously IH/Navistar engineers thought too much water could bypass and put the ball in there.

 

Personal experience, on the other hand, says that it works just fine without it. It warms up quite nicely in the winter(<5 miles = warm air, 190F at 12 miles of highway), and doesn't seem to be too different to my other truck which isn't modified.

It makes it a /lot/ easier to bleed the air out of when draining/refilling with antifreeze, too.

 

The ball is there to prevent flow when the water is flowing, when the water stops the ball drops allowing any trapped air to escape.

This is a common issue with over heating on freshly filled systems, if the ball sticks closed the air/steam becomes trapped in the top of the water jacket ... And because the thermostat is about two inches down it cannot escape there either.

Thus nearly impossible to get the air out of the top ~two inches of the water jacket.

Does it harm to remove the ball, I've never heard of it doing so, I have never heard of anyone removing it either ... I have not heard everything!

The coolant bypass is actually the heater lines ...

-Enjoy
fh : )_~