Master cyl. bleeding

[1960Bird]

I have installed a new master cyl. brake lines, all the tubing, shoes and drums...the whole nine yards. I now understand that I was supposed to bleed the master cyl. before it is installed (bench bleeding).
I don't ever remember bleeding the master cyl. before, although it has been 40 years since I did my last brake job. Is this master cyl. bleeding just needed for a dual brake system or do I have to do this too and if so do I have to remove the master cyl.from the car Then how in the heck do I bleed it?

Thanks for your help.

[RustyNCa]

I have installed a new master cyl. brake lines, all the tubing, shoes and drums...the whole nine yards. I now understand that I was supposed to bleed the master cyl. before it is installed (bench bleeding).
I don't ever remember bleeding the master cyl. before, although it has been 40 years since I did my last brake job. Is this master cyl. bleeding just needed for a dual brake system or do I have to do this too and if so do I have to remove the master cyl.from the car Then how in the heck do I bleed it?

Thanks for your help.

The bench bleeding is to get the air out of the master cyl, seems like you could do it on the car, even though it's probably easier on the bench. I have a bench bleed kit that came with a master cynl I did. You just insert that into the master cyl's outlet and run a tube back into the resevoiur and carefully pump the master till you no longer see air in the tube.

I don't remember being told to do it in the past either, but now that is what is done. I assume it's so when you are bleeding the system, you are only worrying about the lines and you have verified you don't have any air in the master itself.

[JohnG]

Since you already have it on the car, try bleeding it from there - nothing to lose.

You could fill it with fluid, disconnect the line from it and you or someone very slowly work the pedal in and out. Watch for bubbles coming up in the supply. Tap on the side with a rubber mallet now and then to dislodge air pockets. At some point you ought to be pushing fluid out the front opening at which point you're on the road to success. Make sure and put rags under it and wash the area afterwards as the DOT 3 will attack paint on you.

John

[1960Bird]

Thanks

Thanks for your help...

[rhertel]

Bleeding

The new method of bleeding a master cylinder is using a plug where the brake line would go in and pump the cylinder until it is you have no play left. With the bird type, you would need to but the fitting with the stop light switch onto the cylinder and plug the brake line fitting. The a little plastic threaded plug. They are very cheap, any good part store would have them.

Rich Hertel
Master A.S.E. Certified Technician

[Dan Leavens]

Steve JohnG's suuggestion about putting rags under the cylinder is a very good point, if you don't want your paint on the firewall to come off with the DOT 3. This is nasty stuff, as I had to to get my firewall redone from the dripping and the master cylinder repainted ( argent ) when I had them bleeded. Lesson learned

[1960Bird]

Plug the master Cylinder?

Rhertel,
Are you saying that all I need to do is to plug the Master Cylinder brake line fitting and then pump the master cylinder and watch for the air in the reservoir, then when the brake pedal is hard...I'm done. Then I do not need to hook a hose up and run brake fluid back into the master cylinder?

Either way can I do it on the car or must I remove?

[KULTULZ]

Are you saying that all I need to do is to plug the Master Cylinder brake line fitting and then pump the master cylinder and watch for the air in the reservoir, then when the brake pedal is hard...I'm done. Then I do not need to hook a hose up and run brake fluid back into the master cylinder?

Either way can I do it on the car or must I remove?

On the car and gently depress the brake pedal so as not to create more air bubbles. Once you have a hard pedal, reconnect the brake line and bleed the line. No need for return hoses to the reservoir.

[JohnG]

best case have someone pump the pedal for you and stand look down at the resevoir. Have them move it in and out very slowly. You should see streams of bubbles come up to the surface. That's when you're making progress. When you get to the point when the pedal has firmness, you have essentially won. The rest of the exercise is getting air out of the system , but now you have a funcional pump (which is all the pedal and master cylinder really are) to drive new fluid through the system.

What do you guys reading this like for an order to bleed the individual brakes?? My guess would be passenger rear first, then driver's rear then passenger front then finally driver's front. Any thoughts?

John

[protourbird]

The ONLY way you can reliably bleed the master is to bench bleed it with a bench bleed kit. You can pump the pedal until you're blue in the face but if there's air in there only a bench bleed will get it all.

[rhertel]

bleeding

You have to remove the master cylinder and do it off the car.

The bleed procedure for non front wheel drive and non abs brake vehicles , you alway start the farthest wheel from the master cylinder and finish at the closest.

Rich

[1960Bird]

Thanks Everyone...

I'll let you all know how it goes.

[KULTULZ]

The ONLY way you can reliably bleed the master is to bench bleed it with a bench bleed kit. You can pump the pedal until you're blue in the face but if there's air in there only a bench bleed will get it all.

Please explain (to me) how a master cylinder can only be bled on the bench (as long as it is at level on the chassis)? I understand the return line kit, but not the bench. I am dumbfounded here...

[Guest]

You might need a helper but you CAN bleed this on the car????????????

[KULTULZ]

Let me try this again...

The MC is more easily bled off the car if being replaced. But it can be bled on the car say if one runs it out of fluid while bleeding the system.

There are quick kits available that replace the actual brake lines (nylon fittings and tubing) and return the expelled flushed fluid from the MC back into the reservoir bowl(s). One can also fashion a similiar device out of an old brake line. Try to keep the return line below the actual bowl fill line so as not to make a mess and not to ingest air on the return stroke.

Once the hard pedal is realized, you simply remove the adaptor and connect the brake line(s). Bleed the lines again to insure no air was ingested while replacing the brake lines.