427_Roadster

I'm probably showing how little I know about this but is it possible to reverse bleed the brake system? Instead of letting air out the bleed screws, what about pumping brake fluid into them, forcing the air out the master cylinder? I know it would take a lot of fluid to do this, but it would garantee no air in the line. Would the fluid make it past the proportioning valve?
Thanks...
-Tom

rollavette71

I don't think that would work simply because the system is designed to have the fluid flow in one
direction only. But even if it would work, you would need a fitting to go on or replace the bleed fittings
so that you wouldn't be pumping air back in along with the fluid. Does such a fitting exist?

Also, I think you would have a hard time getting the fluid to flow backwards through the master cylinder.

And besides, done correctly, the conventional method should bleed the air out as designed. I've done it three times
without any difficulty.

Hank

Techno

You can put a vacuum pump on the bleeder screw. I've done this but I still manually finished. This is a good way if you want to change your fluid. You have to have the vacuum go to a bottle which catches the fluid. from the bottle to the bleed screw.
The problem I see on the pressuring system is the air bubble is at the top of the caliper. Also how do you know when all the bubbles are gone. I don't think the fluid can back flow because if the fluid gets hot it doesn't over flow the tank, it blows the brake line.

Rockn-Roll

That should bleed the system fine, cause the system is designed for fluid to flow unempeded back up into the master cylinder to relieve pressure or else the wheels would not free up...in fact a clog in the line causes some serious problems. It would not, however, detect leaks in the system which are small enough to allow air into the system, but not large enough to allow brake fluid out. If you use the brake pedal to pump fluid through the system you will be able to discover leaky lines, calipers, wheel cylinders, etc. It would be difficult to find a hose and clamp that is good enough a fit to seal under pressure to the brake bleeder valve nipple though.

rollavette71

Rockn-Roll,

But doesn't the fluid flow in "reverse" in response the brake pedal being released and creating a
vacuum in the system back to the MC? If true, then trying to bleed in reverse would be tricky
because you are (probably) not working the brake pedel during the process and so the fluid would
resist traveling through the MC into the resevoir.

Am I way off here?

Hank

Z-man

This should work fine, but I doubt if you could figure out a way to make a positive seal at the bleed screws. The fluid flows right past the proportioning valve and into the MC. You can see this when you remove wheels and calipers and push on the brake pads. The fluid just rises in the MC. However, in my opinion, this might be more work than bleeding them the regular way.

Bleeding the regular way removes all the air also. I bought the check-valve type bleed screws from Vette Brakes so bleeding my brakes was a one-man job. No air, rock-solid pedal...

Good luck :)