halfmoontrail

Can the master cylinder be "bench-bled" in the car? Existing master cylinder/power booster, new steel lines and hoses, rebuilt calipers.

Trying to gravity bleed, starting with right rear inner. No fluid after hours (and hundreds of pumps on the pedal).

I tried removing the bleeders on the MC, no fluid, even after numerous pumps.

Both the front and back reservoirs of the MC have gone dry in the past.

1. Do I need to bleed the MC?
2. Can it be done in the car?
3. About how long during a gravity bleed on new lines/empty calipers for fluid to make it to right rear? Hours? Days?

Thanks in advance,

Steve

Durango_Boy

#1: & #2: Yes. Buy some barbed nipple fittings with the same thread diameter as the brake line bungs. Thread them in instead of the brake lines. Slip some clear tubing onto the barbed nipples, and insert the end of the tubes into their respective res. Then, pump until you can't see air coming out any more. Rap on the master with a rubber mallot or a deab blow hammer.

#3: Attach the brake lines, and open the bleeders at the calipers. I have seen a gravity bleed take up to 48 hours foro just the rear two. I would do only rear, and then only front. If you have help, you can do the pressure bleed method, where you keep a bleeder closed, have someone pump the pedal, and while he holds it, you release and tighten the bleeder.

If after all that, you still get no fluid to the calipers then you may have a bad valve or crushed lines.

halfmoontrail

Thanks, Durango. All excellent suggestions.

But...I still have a question! What are the bleed screws on the MC for (above the lines out, below the reservoirs)? When are they used, and should I be seeing fluid at them?

Steve

Durango_Boy

Yes, they go directly to the plunger bore of the master. They are for bleeding at the master, and I too have a master with them. They are hard to use, as they will suck air in unless you buy a good set of over-sized bleeders. They are best used after the rest of the system is bled. I replaced every bleeder with check valve bleeders, found in Autozones. They ake bleeding a lot easier, and faster. I even replaced the ones at the master.

Once you have fluid at all calipers, bleed until you no longer get air at each wheel. Go in this pattern:

Driver's Rear
Passenger Rear
Passenger's Front
Driver's Front.

Once you do that, then you can bleed the master using it's bleeders. Remember, installing check valve bleeders will help stop air from being sucked in, and don't bother doing any of the bleeding until the master has been purged of air and hooked back up to the braking system.

halfmoontrail

Thanks! Very clear and helpful direction.

Steve

Durango_Boy

No problem...just take it slow and one step at a time. Good luck.