Master Cylinder Question

[54olds]

I just had my master cylinder re-built for my '54 Olds 88. I bled both front brakes, but I'm still having trouble getting the brakes to work. With the engine off, the pedal is fairly hard. When the car is started, I get almost no pressure at all, and the pedal goes to the floor. Also when I press on the pedal, there is a slight change in engine RPM. I know I have yet to bleed the rear wheels, but I have a few questions that have been bothering me:

1) How can I tell if the vacuum canister is working properly? Could this have anything to do with the problems I've been experiencing? How can it be tested?

2) I am using a Mi-Ty-Vac to bleed each wheel with. Do I need to pump the brake pedal at all?

Thanks for any help!

[ozoneblue]

the rear is the hardest to bleed as it has high spots in it that trap air, Start with RR first .You might have the diaphragm leaking in tour booster. Send some pics of your 54 ,We also own one,

[Oldsguy]

You might want to check if the booster is leaking, that's what it sounds like to me.

[54olds]

Thanks for the tips - I'll check the booster and see if the problem might be there. Can you test whether or not it's the booster by disconnecting it and plugging the vacuum line?

Here's a couple of pics - I just painted it this fall.

[Oldsguy]

I like the color. Buy a vacuum tester and see if it holds vacuum. You might notice that the tune is difficult to get right on too because of the vacuum leak. Solving one problem might solve two.

[ozoneblue]

You still need to get the pedal up. By bleeding .With the car running the pedal should push easy,but not to the floor,With no Vac the pedal should be hard to push,The Bendix Tredalvac system parts are available at Kanter.This is a very different type system as the master cylinder uses no plunger so to speak it works on volume so you must make sure the cap is screwed on tight .Nice looking car from the pics ,if you need more info, you can send a PM larry@vintageozarks.com

[54olds]

Thanks. I plan on bleeding the rear wheels this afternoon, so I'll see if that has any effect. I noticed a solenoid attached to the vacuum reservoir. I took it off, took it apart and cleaned and tested it. It is basically a valve that opens or closes the reservoir from the rest of the brake vacuum lines. Here is a pic:



Is this supposed to be activated when the brake pedal is pushed? I'm going to check for voltages later, and I'm wondering if 12v. is sent to the solenoid only when the brake pedal is depressed.

Thanks!

[Olds64]

SWEET CAR! You know, I don't know if it will have anything to do with your problem but you might not want to bleed your brakes with the Mi Ty Vac Tool. I have never had any luck with these. IMHO the best way to bleed brakes is with a buddy. Plus you can hang out and drink beer afterward.

[54olds]

LOL - thanks! That there's good advise!

[ozoneblue]

WOAH according to your pic not the sane system as mine & I think Kieths is also a tredalvac . My vacuum reserve tank resembles , as Keith said a scuba tank along the frame Ask the guys who re built your MC what system you have . Cant get to my books right now but Bendix made other systems also .Does your pedal say POWER BRAKE ? Is the master cyl bolted on the back side of the booster?

[54olds]

Here is a pic of the type of master cylinder I have (mine has the filler tube and dual vacuum connections):


Yes, the vacuum reservoir does look like a scuba tank. The solenoid is attached to the reservoir by a short piece of vacuum tube, and has a ground wire and a hot wire connection. When I took the solenoid apart, it has a rubber stopper which, when activated, pushes against the inner port and blocks air flow. The brake pedal does say POWER BRAKE.

[54olds]

I've drawn a quick diagram of how all this fits together (hope this helps in understanding my system)

[ozoneblue]

Yes is the same as mine Just dont remember the solenoid. I will check mine as soon as snow is gone.Un fortunately shop isn't big enough for customers cars & mine! I would guess it gets power when brakes are applied ( you can never have a shop too big )
.