[justatroll]

Originally Posted by Poodles

Because it's NOT a closed system. Even if it was, it builds it's own natural pressure!.

Part of this discussion keeps revolving around some misconceptions obout HOW these systems work:

You stated the following:

Originally Posted by Poodles

BS. Cooling system works because it's pressurized. Lose the pressure and it causes localized boiling, massive over pressure, and very rapid overheating. Pinhole leak is all it takes to lose pressure.

When talking about a cooling system, there are TWO kinds of "pressure".

The system may (or may NOT be) under an increased absolute pressure with respect to atmospheric pressure. The system is (by definition) "Closed" as it is allowed to have an absolute pressure that is different than the atmosphere. It is also "closed" due to the fact that the system's water pump does not have to pump against any "head" (there is no uphill vs downhill). Another condition of a "closed loop" system is that it's working fluid volume remains constant during operation (if you let any coolant escape, it doesnt get replenished).

The system most definitely MUST have a differential pressure which is completely different than absolute pressure.

For the system to provide cooling it requires differential pressure (provided by the water pump) to circulate the water through the cooling passages and through the heat exchanger (radiator).
No differential pressure, no flow, no cooling.

The fact that the system pressurizes due to the water reaching boiling temperature has absolutely nothing to do with the operation of the system EXCEPT: If the system did not maintain a CLOSED LOOP SYSTEM during steady state operation, the coolant would boil away and leave you with no working fluid.

So does the system need to be "pressurized" wrt to atmospheric pressure to operate?
NO.

Now what are we talking about wrt burping and why can the system stop "pumping" and overheat badly?

What can stop the cooling system from operating?
1 - The heat cannot move from the heat source (engine) to the working fluid
2 - The heat cannot move from the working fluid to the heat exchanger (radiator)
3 - The heat exchanger cannot transfer heat to the heat sink (atmosphere).
4 - The working fluid cannot move from the heat source to the heat exchanger (pump not pumping)

So now that we have that cleared up, we can refer to the 4 conditions above when trying to figure out why the system stopped working.


And lets not forget that there are three possibilities occurring in the OPs case:

A - The Engine is fine except the cooling system is malfunctioning
B - The Cooling system is fine but the engine is producing too much heat and the cooling system cannot handle the heat load.
C - The engine is not really overheating but the temperature indicators are malfunctioning.

OR....
Has anyone suggested checking for:
Oil in the water?
Water in the Oil?
Inability of the cooling system to maintain pressure under a pressure test?

Because any of those things could indicate a blown head gasket.

Or you could just stick your HEAD IN THERE and LOOK for a blown head gasket.....

Originally Posted by extrashaky

LOL. Let's start with this:
In your quest to make this easy diagnosis as complicated as possible, you're missing the simple fact that it isn't necessary to heat up and cool off the motor to poke your noggin under the car and visually inspect for leaks of not-invisible coolant.

And YOU are too dense to realize two simple facts (no really they ARE FACTS, but extra will work overtime to say otherwise):
some leaks (such as a blown head gasket) will only present themselves when the system is under pressure
it is infinitely easier to stick your head in an engine bay and look for coolant leaks when the engine is not running and cold as opposed to running and HOT.