Purging Air
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Senior User
Joined: Sep 2017
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From: Downriver,Mi
Purging Air
So, I think I'm calling bull scat.... we've all heard and we've all turned our heat on high while purging air out of our radiators. But, why. We're not moving any sort of a mechanism tied to the fluid your trying to remove air from. So why do we do it? Sure to feel the nice and toasty air but why else?
Cargo Master
Joined: Jul 2009
Posts: 2,541
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From: Des Moines
1) The air flow across the heater core draws heat from the antifreeze, lowering it’s temperature and pressure in that area of the system. This creates a pressure difference which causes the hotter/higher pressure antifreeze to flow towards the cooler/lower pressure area of the system. That’s how flow through the heater core is created. There is some flow through the core without the fan on, but it’s minimal - the pressure difference is what really gets it moving.
2) Air always rises to the highest point in the system. On many vehicles, the heater core is the highest point. With the pressure difference created by running the fan on high, flow through the core is at its fastest and the chances of bleeding the system more completely are increased.
2) Air always rises to the highest point in the system. On many vehicles, the heater core is the highest point. With the pressure difference created by running the fan on high, flow through the core is at its fastest and the chances of bleeding the system more completely are increased.
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Senior User
Joined: Sep 2017
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From: Downriver,Mi
Jake, no offense what so ever.But, this is exactly what I'm saying. WE ALL do it. But, your heater controls operate a blend door and a fan. NOT a water mixture valve.
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Senior User
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From: Downriver,Mi
1) The air flow across the heater core draws heat from the antifreeze, lowering it’s temperature and pressure in that area of the system. This creates a pressure difference which causes the hotter/higher pressure antifreeze to flow towards the cooler/lower pressure area of the system. That’s how flow through the heater core is created. There is some flow through the core without the fan on, but it’s minimal - the pressure difference is what really gets it moving.
2) Air always rises to the highest point in the system. On many vehicles, the heater core is the highest point. With the pressure difference created by running the fan on high, flow through the core is at its fastest and the chances of bleeding the system more completely are increased.
2) Air always rises to the highest point in the system. On many vehicles, the heater core is the highest point. With the pressure difference created by running the fan on high, flow through the core is at its fastest and the chances of bleeding the system more completely are increased.
The heater core while not primary gets a fair amount of flow. The late 90's and early 00's Taurus's had a heater bypass line because it was very difficult to bleed the system. The heater core since it was removed from prime flow would get obstructed with contaminants when the car got some miles on it.
Cargo Master
Joined: Jul 2009
Posts: 2,541
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From: Des Moines
I put my vehicles up on ramps also.
The heater core while not primary gets a fair amount of flow. The late 90's and early 00's Taurus's had a heater bypass line because it was very difficult to bleed the system. The heater core since it was removed from prime flow would get obstructed with contaminants when the car got some miles on it.
The heater core while not primary gets a fair amount of flow. The late 90's and early 00's Taurus's had a heater bypass line because it was very difficult to bleed the system. The heater core since it was removed from prime flow would get obstructed with contaminants when the car got some miles on it.
The process was developed at a time when static filling of the cooling system was pretty much the only way to do it. There are fillers now that pull the cooling system into a vacuum and then coolant is sucked into the system, eliminating the need for bleeding in most cases.
Laughing Gas
Joined: Oct 2014
Posts: 946
Likes: 186
From: Carnation, Wah
I just drive around and top off the reservoir bottle as needed.
No water valve in the heater circuit, huh?
I never looked.
But the water pump has to do something for flow,
even if it can't generate enough pressure to actually bleed the high spots,
as I'm usually adding coolant 2 or 3 times, not 30.
t
used to a positive flow system, too.
No water valve in the heater circuit, huh?
I never looked.
But the water pump has to do something for flow,
even if it can't generate enough pressure to actually bleed the high spots,
as I'm usually adding coolant 2 or 3 times, not 30.
t
used to a positive flow system, too.
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Elder User
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The only motor i ever had an issue with was the 300-6. Even that was short lived after a 1/2hr drive. All the other motors never caused any grief.
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