Vacuum Bleeding Power Steering Systems.

[George7941]

How does it work? How does subjecting the reservoir to vacuum eliminate air pockets?

The only explanation I can think of is any air bubble will expand a lot under 20 to 25 in Hg vacuum, let us say, ten times. Thus after system is subjected to vacuum there will only be 1/10th as much air left in the system. Does this sound about right?

Same question can be asked about vacuum filling coolant systems with Airlift to eliminate air pockets.

 

[George7941]

Here is a Youtube video showing vacuum bleeding a power steering system
http://www.youtube.com/watch?v=egzQYcxaPGU

 

[morris]

its just a simple hydraulic system. just have some fluid to refill the resavor. just run the engine and turn the wheel back and forth. then take it for slow ride. just keep it resavor . fill.

 

[George7941]

I have never had a steering system or cooling system that needed vacuum bleeding to eliminate air but, apparently, there are some vehicles where the trapped air is very difficult to eliminate. The Youtube video shows a car where even after repeated turns lock to lock, the pump is still moaning from trapped air.

I was just curious as to how vacuum bleeding worked.