1960s Bleeding front brakes on 1966 coupe

[Cadillac George]

Hi,

Having trouble getting the air out the front break lines.  The back breaks bleed ok. This car has not moved for 20 years. The front brake look like they have been replaced and the brake cylinders are not leaking.  I have flushed the fluid and checked the solid lines.  I just get a lot of air in the bleed lines when I open the bleeder valve for the front breaks.  I removed the master brake cover and see the rear brake reservoir squirts up when I slowly press the brake peddle but nothing from the reservoir for the front brakes. 

At a lost of what to do!   Thinking of replacing the master cylinder but not sure.  Any suggestions would be appreciated.  Thanks

[TJ Hopland]

If everything was normal you should not see anything happening when looking in the reservoir and operating the pedal.  Maybe the MC lost its 'prime'?  I would be tempted to disconnect it and bleed it before just replacing it.       

You can still buy a 'master cylinder bleed kit' which is some plastic fittings that thread in where the brake lines go then a short section of hose that you loop back into the reservoir.  Some MCs even for older stuff are 'self bleeding' and come with plastic plugs that allow you to bleed them but it can be hard to tell if that is what you have or not but the hose system always works.

Bleeding the MC should give you an idea if the MC is decent so you don't end up wasting time replacing it or trying to bleed something that is broke.  One bleeding method that can help is good old gravity.  Open those front ones and let em go for a while possibly hours and see if gravity does the trick.  Keep an eye on the fluid level in the res.  If it ever gets low you have to start over.

Gravity won't usually do it all but may get things going enough that the tried and true 2 person method can finish things off.   

[The Tassie Devil(le)]

If you need to make your own MC priming kit, this is what I did.   I find that the factory-supplied ones made from plastic and rubber aren't as easy to control when doing it on your own.

Really easy to prime on the bench as it takes a bit of pumping to get it done.

This one is for Ford MC, but others use a different flare and nut.

Bruce.

[Cadillac George]

Thanks for the note on the MC bleed kit.  I was following the instructions in the manual that said open both fittings on the outlet side of the master cylinder then pump it 5 times.  I have never done this before but thought they know better than me.  I will see if I can get the MC bleeder kit tomorrow and try again.

[The Tassie Devil(le)]

The big trouble with bleeding the M/c whilst it is attached to the Vacuum Booster is that you WILL get messy brake fluid where you don't want it.   Especially in the engine bay, splashing everywhere you don't want it.

I have found that sometimes it takes a lot more than 5 pumps to get it right.

Bruce.

[Daryl Chesterman]

The big trouble with bleeding the M/c whilst it is attached to the Vacuum Booster is that you WILL get messy brake fluid where you don't want it.   Especially in the engine bay, splashing everywhere you don't want it.

Bruce is right about getting brake fluid everywhere.  You do NOT want to get brake fluid on any paint as brake fluid is extremely caustic to paint!  Brake fluid is an excellent paint remover!

The metal lines that Bruce shows is the best way to bleed the master cylinder. You can go to your local auto parts jobber and get 12" lengths of brake line with the fittings on them and bend them so that they recycle the fluid back to the master cylinder reservoir, enabling one person to do the bleeding of the master cylinder.

Daryl Chesterman

[35-709]

"Car hasn't moved for 20 years!" 
I would not attempt to drive that (or any) car on public roads until every brake component has been rebuilt or replaced and every rubber brake hose has been replaced also.  The rubber brake lines fail internally and can look OK from the outside but have deteriorated/collapsed on the inside.  Unused and unmaintained brake systems this old are NOT an area that a flush and bleed is sufficient.  That is a heavy car and (very) good brakes are essential.  The brake cylinders may not be leaking, but have they been inspected by pulling back the rubbers on each end to see what kind of corrosion is there? 
Actually, if it were mine, every wheel cylinder would already be off the car and rebuilt or replaced no matter what they looked like from the outside - same with the master.  Rebuild kits are cheap as are complete new wheel cylinders at NAPA, etc.  In my opinion, you are playing with fire and inviting disaster by trying to get away with a quickie brake job.  Brakes are the last place you want to save a little time and a few bucks.  Ever have a brake failure in traffic?  If you are lucky, your biggest problem will be trying to swallow your heart back down.  Worse, you could damage your car and someone else's, worse yet, you could cause injury or death.  If you are not familiar with brake maintenance and maintenance procedures, get someone experienced to help you - hands on.         

[Michael Petti]

Ditto! I had that brake failure.  Not fun. Rebuild as many parts as you can. New parts are all made in China and of dubious quality. I had a newer hose collapse on the inside. Also had a new wheel cylinder with a stuck piston and a new master cylider leak. Stainless steel brake lines are advisable too.

[TJ Hopland]

I was reading it as someone had more recently started replacing parts not that the replaced parts were at least 20 years old and sat the whole time.