The other day I had replaced the master cylinder and rear wheel cylinders on my 1969 Cutlass. This car had been previously caught in a flood, and has been sitting for a few years, and I am in the process of making it road worthy. I decided to blow out the hard lines while I was working on the drums. With the lines completely disconnected, I was able to get air to travel through the line at the rear from driver side to passenger and vice versa, but I cannot get air to travel from the master cylinder connection to the rear, or from the rear to the front.

I decided to hook up the hard lines at the master cylinder but not the wheel cylinders, and attempt to pump fluid through them. The pedal would move a bit but no fluid came out. My brother then released the rear line connection at the master cylinder as I was holding the brake pedal, and it went down. When he released the connection the pedal moved like it should and the master cylinder bubbled.

Prior to installation I performed the bench bleed to prime the wheel and master cylinders.

I have ruled out a rusted line as the hydraulic pressure from pumping the brakes should have blown a hole in the line. Or at least I would think.

Maybe there is a kink in the line?

Is there a check valve somewhere on the line that I need to release?

I might need to just replace that line, but it looks to be in good condition.

any insight is very helpful.

Thank you in advance.

 

Is this drum/drum or disk/drum (f/r) brake system? There is either a distribution block or a combination valve in the brake line system in the engine bay. I'm not certain if 1969 was OEM stock distribution block or combination valve. Do you have the CSM?

 

It is a drum/drum combo with a booster.

I do have a Chilton but it is with the car about an hour from my house currently. I probably should have checked there first.

 

time for a rear hose replacement

 

I'll let someone else address this but I believe a drum/drum brake system employs a distribution block and NOT a combination valve.
In any case, I was only addressing your first question - there is no check valve in the brake system, but I suspect you have a distribution block rather than a combination valve (which were employed on disc brakes).
BTW, how deep was the flood water in this vehicle? Do you know?

 

If your line to rear went dry likely you lost your prime. Lines must be full when bolting on a bench bled master cylinder else air will be drawn back into the master, I have had this trouble trying to bleed brakes with a new master and empty lines...

 

Is there something with the distribution block that could fail? Does it have a valve? Rust build up? I always thought a distribution block was just a bunch of passageways and mounting points.

The house and garage it was in had water marks at 22" above slab. The door card of the cutlass has a watermark about 3" above the sill trim. There was water in the cab, I had to gut the interior. Water in the engine and transmission rear end etc. I have managed to get the engine running again. I think the transmission is toast, and the rear end needs to be rebuilt.

I got a bit more than just the rubber hoses to replace But I will replace those as well. Hopefully that will solve the issue.

it is my intent to fully restore this vehicle.

 

That's some serious water intrusion. Salt water, brackish or fresh water?

Here's a nice write-up discussing distribution block, metering valve, combination valve. See Joe's Post #20
Joe has had a handle on the braking system components since right around the time the Earth cooled.

Bleeding Brake Proportioning Valve

 

Just found the quote system. i'll make a newbie post.

The line most likely is dry. But I would think compressed air would be able to get through.

Seems like the next step is replace the rubber lines at the rear end. and to prime the hard lines with a syringe.

Is there anything in the distribution block that might cause this?

 

It was freshwater. But the neighborhood it occurred in has all septic systems. So a combination of fresh, septic, fertilizer, insecticide, and whatever else.
The flood devastated this car. I think most people would part out what is still good and scrap the rest, but I have a strong sentimental attachment to it. I know I'm in for the long haul.

Thanks for the awesome write up. My knowledge on brake systems is limited.

 

Good for you for saving it. Going to be and has been some work. Patience is key. If you have the chance, grab a 1969 CSM as opposed to your Chilton. While I do like a good Chilton, the 1969 CSM is "bible" direct from GM. Get an original hard copy (paperback) - not the digital version. Plenty still available. Might be a little pricey (maybe), but for ~$50-$75 you have "the" authoritative dictionary on your 1969. Check around, many of the suppliers who sell the paperback edition also will toss in a digital Assembly Manual, Parts Manual and Fisher Body Manual. Grab a paperback original GM CSM and you cannot go wrong. Look forward towards your progress. Good luck!

 

Here's an original (as stated in the write-up) in VG condition.

https://www.ebay.com/itm/1969-OLDS-S...-/292842197472

 

Disconnect the main line from the distribution block to the rear hose connection. Try blowing air through the line, if there is no air going through the main line from front to rear I'd say that is your issue. If you can get air to flow then move to the next set of joints, front or rear until you find the blockage.

 

I had the same issue replaced the master cylinder as it was leaking by along with both rear wheel cylinders. The lines twisted off at the cylinders so I replaced them. Using the regular bleeding method did nothing on my drum/drum 70 Cutlass S, no fluid to the back, make sure the combination valve didn't move to block fluid to the rear brakes, mine was fine. A Motive pressure bleeder pushed fluid through and problem solved.

 

Be sure to bench bleed the master. Otherwise the pedal is mush and no fluid gets pushed to any calipers or wheel cylinders.

 

There is one rubber line at the rear of the car which collapses internally and stops fluid going to the rear brakes and requires replacement. It looks fine to the naked eye, but inside it is a mess and is stopped up. You can check this by taking the metal line going to the rubber line from the front loose and see if you get fluid from the master cylinder. If there is fluid there but not at the wheels BOOM, bad rubber line.

 

How about a simple troubleshooting process to figure out WHERE the blockage is?
1) Do you get fluid out of the M/C ports when you push the pedal? If yes...
2) Connect the hard lines to the M/C and disconnect from the distribution block. If you get fluid out of those lines, then...
3) Connect the lines to the distribution block inlets, disconnect from the distribution block outlets. If you get fluid then...

You get the idea. Work your way down the lines from the M/C to the wheels and figure out where the problem is. We could spend weeks here contemplating our navels, or you could spend an hour on the car and figure this out with no questions.