Help Master Cylinder Puking

[blewbyoutobad]

Found brake fluid under my car today from the master cylinder. The rear chamber was almost dry and the master cyl was wet on the bottom. Using silicone fluid and the master cyl is about 10 years old but less than a thousand miles. Anyone have experience with this kind of problem.
Thanks FABO

 

[dartfreak75]

My guess is the seals in the bore are shot.
Check and see if there is any fluid running down the firewall.

 

[Brooks James]

If it’s 67-72 a body drum brakes I got one I give I’ll give you

 

[blewbyoutobad]

Firewall is dry. Running down front of master where rear chamber is and dripping.

If it’s 67-72 a body drum brakes I got one I give I’ll give you

I have discs on the front, thanks anyway. I'll go ahead and order one.

 

[Dana67Dart]

is there is a bolt under the mc to keep the rear piston from moving too far?

Might be leaking from there.

 

[blewbyoutobad]

is there is a bolt under the mc to keep the rear piston from moving too far?

Might be leaking from there.

I will check when I pull it. If its on the outside there is nothing there.

 

[blewbyoutobad]

Got the new master cylinder. Some differences. How does the rod come out of the old one. Do the screw and keepers stay in place on the new one when installed? Has a screw on bottom of cylinder. Best way to bleed before install.
Thanks FABO

 

[Dana67Dart]

Rod should pull out, there is a rubber keeper in the rearmost piston.

It is reported to take a bit of force to get it out.

Don't toss the old MC it is rebuildable.

 

[blewbyoutobad]

Finally got it out. What a bear! Yes I have a core charge. Everythings up and running except I bent the switch bracket so gotta make sure brake lights work in the morning.

 

[Dana67Dart]

Everythings up and running except I bent the switch bracket so gotta make sure brake lights work in the morning

Streighten it up then if need be adjust it with the bolt from the pass side of the column.

If the core charge is small keep the core or sell it to someone who wants to have an OEM to rebuild.

 

[BillGrissom]

I hope the new MC came with a new rubber bushing to put on the end of your brake rod to secure in in the MC piston. If not, it might be possible for the rod to come out so you can't brake. I don't know if the pedal can pull it back far enough for that. Looks like you have a power brake MC you are using for manual brakes. Manual MC's should have a dust-bellow bolted to them, which also secures the piston in the bore as those keepers did. Most manual MC's come with the rod and bellows installed (check rockauto photos).

I always bleed the MC in-car, using the brake pedal. You might need 50 strokes to sweep all the air bubbles out. Also would have been easier to pop out the brake rod while the old MC was in-car, using the brake pedal as a lever. Remove the brake switch first so you don't bang it. That switch always needs adjusting afterwards. It should sense pedal motion but not affect it, i.e. pedal shouldn't bottom-out on the switch.