Burping Cooling System after Vacuum Fill

[Donald]

If you are patient a good sealed system will self purge the air out in a few cool/heat cycles. Technically it does not matter what the level in the over flow is as long as the bottom is covered in coolant so as to not suck up air on cool down. When the system is dead cold the radiator should be 100% full.

As the system heats up under pressure, any air in the coolant becomes dissolved in the coolant. As it is pushed into the overflow, which is not under pressure, the air undissolves. I've found replacing the overflow tube with clear tubing shows the coolant in the hose so you know the radiator is full. If there is air in the hose there is air in the coolant and more than likely some sort of minor vacuum leak on cool down.

Best thing they ever did is to go to those pressurized coolant tanks.

Not true in my Volvo Penta boat engine. But then again it has a heat exchanger and water cooled exhaust manifold. But the proper method (it's on a label I did not read at first) is to run the engine at 2000 RPM for 5 or 10 min. The water pump just does not move the water fast enough at idle.

 

[SHOZ]

Not true in my Volvo Penta boat engine. But then again it has a heat exchanger and water cooled exhaust manifold. But the proper method (it's on a label I did not read at first) is to run the engine at 2000 RPM for 5 or 10 min. The water pump just does not move the water fast enough at idle.

If it has a pressure cap and an overflow it is true. Just take s long time for those engines made with air pockets.

I always squeeze the hoses and I have top of the system small hose to use for filling if I'm picky.

 

[roaniecowpony]

If you are patient a good sealed system will self purge the air out in a few cool/heat cycles. Technically it does not matter what the level in the over flow is as long as the bottom is covered in coolant so as to not suck up air on cool down. When the system is dead cold the radiator should be 100% full.

As the system heats up under pressure, any air in the coolant becomes dissolved in the coolant. As it is pushed into the overflow, which is not under pressure, the air undissolves. I've found replacing the overflow tube with clear tubing shows the coolant in the hose so you know the radiator is full. If there is air in the hose there is air in the coolant and more than likely some sort of minor vacuum leak on cool down.

Best thing they ever did is to go to those pressurized coolant tanks.

After a quick bit of research, I think these charts have some specific information on soluability of air into solution at elevated pressures and temperatures. https://www.engineeringtoolbox.com/air-solubility-water-d_639.html

Note the first table or second chart. 0 psi at 60F and the 20 psi at 190F have the same soluability. At 20 psi, above 190F air soluability is less than air soluability at 0 psi at 60F.

 

[The Critic]

If you are patient a good sealed system will self purge the air out in a few cool/heat cycles. Technically it does not matter what the level in the over flow is as long as the bottom is covered in coolant so as to not suck up air on cool down. When the system is dead cold the radiator should be 100% full.

As the system heats up under pressure, any air in the coolant becomes dissolved in the coolant. As it is pushed into the overflow, which is not under pressure, the air undissolves. I've found replacing the overflow tube with clear tubing shows the coolant in the hose so you know the radiator is full. If there is air in the hose there is air in the coolant and more than likely some sort of minor vacuum leak on cool down.

Best thing they ever did is to go to those pressurized coolant tanks.

A few heat cycles is too long. The air pockets can cause overheating and damage components.