I might as well step on a few other toes while retaining water -
Quote:
Just curious about bench bleeding. If you fill and bleed the MC on the bench and then install it into the car you have to hook up open lines to it. Those open lines have air in them, isn't that defeating the purpose of the bench bleed?
|
No, it is not defeating the bench bleed.
Quote:
|
When you bench bleed you have a little air left at the end of the master cylinder where the line goes. You leave the line loose and have somebody push down on the pedal which forces that last little bit of air out of the master cylinder and then you tighten the line when the fluid starts to come out. From then on fluid will be forced down the lines and any air will be ahead of the fluid and pushed out. An air bubble cannot go anywhere but down and out.
|
If the MC is bench bled correctly, there will be no air in the MC.
The problem(s) occurs when the lines are attached to the MC and the fluid beyond the check valve(s) runs out while tightening the line fittings and there is resulting air introduced into the lines.
If you are really lucky, having someone slowly push the brake pedal slightly will force the air out while tightening the fitting(s).
Now in my world this is called taking a chance. The complete system needs to be bled at that point especially if the original MC was defective in such a way as it introduced air into the system. This will also flush the system of old fluid and possibly any contaminates in the system.
Air will always rise in a closed system. One good reason for reverse bleeding.