67 DeVille brake booster and master cylinder

[lou-q]

The pedal was almost to the floor when we started bleeding the right rear but I did not see any air come out. When I could see clean fluid and the pedal was coming up I moved to the left rear and while doing it the wrench slipped off the bleeder when she was releasing the pedal and also sucked the reservoir almost dry.
So we started all over and now I can't get the pedal to come up at all. It lets fluid out when I open the bleeders but not as much as before.
Could the master or booster have failed?
This car was a barn find that was stored at least for 12 years, but probably longer.
The wheel cylinders are not leaking.
I bled 3 or 4 ounces out of each of the rear brakes with no air bubbles and no improvement.
Should I start by buying a new booster and master cylinder.
Cadillac used Delco Moraine and Bendix in 67. If you are replacing both does it matter if you use either?
Thanks in advance,
Lou

[Evan Wojtkiewicz]

The pedal's on the floor and won't pop up at all? I'd say master cylinder. There's a spring in the master that acts as the pedal return. I got my new Bendix-style (not reman) master cylinder from O'Reilly. It seems to work well. You could have yours rebuilt if you really want.

Seeing as how the booster/master cylinder are the only differences in brake parts for our cars, I don't see why you couldn't change out Delco for Bendix if you're doing both. Hopefully somebody can confirm this.

Good luck!

[lou-q]

The pedal's on the floor and won't pop up at all? I'd say master cylinder. There's a spring in the master that acts as the pedal return. I got my new Bendix-style (not reman) master cylinder from O'Reilly. It seems to work well. You could have yours rebuilt if you really want.

Seeing as how the booster/master cylinder are the only differences in brake parts for our cars, I don't see why you couldn't change out Delco for Bendix if you're doing both. Hopefully somebody can confirm this.

Good luck!
The pedal springs back up, just no resistance when you step on it and you hear a wooshing noice when you step on it.
Also the brake light comes on when the pedal goes down 2 3/4".
Lou

[Evan Wojtkiewicz]

Maybe you just have a bleeder screw loose? All I know is that it took me an entire day and a lot of fluid when I bled my brakes a few months ago. To be fair, it was my first time doing brake work of that caliber or caliper (ha ha). I don't look forward to ever having to do it again.

If the bleeder screws are tight (especially the ones on wheel cylinders you're not bleeding at the moment), That probably means there's air in the line somewhere? Maybe you have a pinched line somewhere? It happened to me.

[lou-q]

Thanks,
Back on it tomrrow.
Lou

[76eldo]

I'd try the master cylinder.  The master cylinder will pump fluid through the system, the function of the booster just makes it easier.  When I recently worked on a 60 master cylinder I was surprised at how much fluid needed to be bled through in order to get a normal feeling pedal. If that doesn't work, go to the next step. Remove the master cylinder first to determine if you have a Moraine or Bendix style.  Then get a rebuilt one.  Both styles are available and relatively inexpensive.

Here's a recent post that may help regarding a 1960 I worked on.

http://forums.cadillaclasalleclub.org/index.php?topic=138856.msg320680#msg320680

Brian

[DBDB]

Very simple , you mention , barn find , pumping the pedal completely down , meant that the piston in the master cilinder went down all the way and the rubber in the master cylinder is damaged because it came at the end of the cylinder where it was not in years and where the cilinder wall had probably some rust or was not clean .

[DBDB]

In fact anytime you bleed brakes on a car with brake system untouched since long time running or not NEVER push the brake pedal completely down otherwise you have a big chance to damage the rubbers inside the master cylinder because it will travel to deep where it will be damaged from rust or unclean cylinder walls .

[savemy67]

Hello Lou,

The previous owner of my '67 Sean DeVille replaced the master cylinder.  The replacement must be an aftermarket unit because it is not identical to either the Delco or Bendix types originally installed on the car.  Using the shop manual as a guide, I took my master cylinder apart, cleaned it, and put it back together and bench bled it.  It works fine.

I agree with DBDB.  After sitting so long, you should probably take everything apart, clean and inspect everything, and replace parts that are defective.  My front wheel cylinders did not leak, but they were full of a rusty combination of brake fluid and water.  The brake warning light on the dash comes on when the brake pedal travels too far.  This was Cadillac's way of notifying a driver that there was a problem with the hydraulic system.

Christopher Winter