No brakes! Pedal goes to floor with engine running.

[Project Sketchy]

The 67 Newport has been sitting for about 10 months. Got in, started her up, pushed in the brake pedal and it went right to the floor (and then made an odd growl almost like anti-locks will do). A sideways glance at the brake-fluid level confirmed what we already knew but were trying not to think about....the master cylinder was leaking. So, rebuilt the master cylinder, bolted it back up and proceeded to bleed the master and then the system with the youngest kid pumping the pedal while I cracked open the bleeder at the wheel cylinders. The bubbles stopped coming out but it still took a couple of pumps to get the brake to feel solid. We were happy and expecting to celebrate with a few burnouts in the driveway...BUT...as soon as we started the engine, the pedal went immediately to the floor. No resistance at all. Nada. Nothing. Zilch. No leaks we can see. Turn off the engine, pump the pedal a few times and it has firm resistance again. Ideas?

 

[jimmyessbee]

It just needs to be bled better.

 

[azblackhemi]

Did you bench bleed the rebuilt master cylinder?

 

[Project Sketchy]

I used my trusty vacuum bleeder to suck the fluid through it while kids kept it topped off. All told, bleeding the master and brakes took a little over a 1/2 of a new, 1 quart bottle. Just seems strange that it could have enough air still in a two line system to make the pedal drop right to the floor and not be able to build ANY pressure. Before I pull all the drums, I'll bribe my assistants into another try.

 

[Davea Lux]

I used my trusty vacuum bleeder to suck the fluid through it while kids kept it topped off. All told, bleeding the master and brakes took a little over a 1/2 of a new, 1 quart bottle. Just seems strange that it could have enough air still in a two line system to make the pedal drop right to the floor and not be able to build ANY pressure. Before I pull all the drums, I'll bribe my assistants into another try.

As noted, bleed the brakes again. I would strongly suggest that you pull all 4 wheels and check each cylinder for leakage and also check the hoses. While you have the drums off, check to be sure that all of the adjusters are in place and that the shoes a making good contact with the brake drums. As the fluid in the system went away while the car sat, there is a good possibility that one or more brake cylinders is also leaking. If any of them show signs of leakage, replace or rebuild all of them. Corrosion in the system sufficient to take out the master cylinder will usually also be present in the rest of the system.

Dave

 

[Project Sketchy]

Darn. I hate brakes. I was trying to avoid having to fight getting the drums off, but you're 100% right. My intention is to have this thing ready for the 2023 Power Tour and working brakes would sure make the trip more enjoyable. 2022 was hot and anything not up to par didn't survive....I was happy to park next to this little gem with the vintage bumper sticker.

 

[1970FuryConv]

Darn. I hate brakes. I was trying to avoid having to fight getting the drums off, but you're 100% right. My intention is to have this thing ready for the 2023 Power Tour and working brakes would sure make the trip more enjoyable. 2022 was hot and anything not up to par didn't survive....I was happy to park next to this little gem with the vintage bumper sticker.

View attachment 565342

I agree with checking the wheel cylinders. If you had a firm pedal and later no pedal, slow leak at wheel cylinder is most obvious problem. Brake fluid at the bottom rear of one of the drums is the sign of this trouble. Of course, hoses and lines are a possibility too.

 

[57fury440]

Are they adjusted correctly? I agree with above and would check for a leak somewhere.

 

[furious70]

An immediate pedal to the floor is a big problem that should in theory be easy to find. With the engine running so you have boost, no amount of pumping will build any pedal feel?

 

[Project Sketchy]

Hi furious70....with engine running, no matter how many pumps on the pedal, it doesn't build any resistance. That's what is confusing me.

Engine OFF: Firm pedal after 2-3 pumps.
Engine ON: Pedal has no resistance. Pumping does nothing.

I always thought that, with the engine running, the only difference would be the pedal would require less pressure due to the effects of the booster. I'm going to go with the advice here and re-bleed and pull the drums to check a wheel-cylinder hasn't popped a seal.

 

[furious70]

well, you may just be feeling the mechanical effort in the booster with the car off, presumably you're not creating any real psi at the wheels with the engine on or off.
Where in Iowa are you?

 

[Project Sketchy]

Hmmm...that is an interesting point. Now I'm curious to what will happen if I raise a front tire and see if it spins freely while the brake is pressed (engine off and on)

 

[57fury440]

I know that you have already bled them more than once. I would give it one more try. If that doesn't work, I would remove all the drums to see what is going on. I think if a wheel cylinder was leaking it could do that, but if it was blown out I don't think you would get anything from the pedal. Are the brake lines and hoses fairly new or are the old and original? I would look at everything at this point.

 

[Project Sketchy]

Update...
First checked fluid level and brake function with the engine on/off. Nothing changed. Nope, it didn't magically fix itself. Dang.

Decided to pop passenger rear drum off and have a peek. Wheel came off easy---turns out 3 of 5 wheel studs are stripped (wish I hadn't seen that). Much to my surprise I didn't have to fight getting the drum off. There was no ridge on the drum---looked like it was freshly turned---and shoes,plates/springs/etc were in great shape. I turned the adjuster out a few clicks to take up some slack so I had just had the slightest bit of resistance when I put the drum back on.

With about 3 foot of clear tubing on the bleeder, the kid pumped the brakes up and I cracked the screw loose. We did this 3-4 times with no bubbles, just a nice solid column of brake fluid. Pulled the drum off and no leaks. Put it back on and figured since I was already dirty and rolling among the leaves and ticks, I might as well double-down and bleed it again. About the 3 time I noticed some small bubbles in the hose and then on the next try, a long stream of air. It took several more cycles to get back to solid fluid.

At that point, the pedal was very firm (no need to pump), so we started the engine and...Gordon Bennett!!!! Solid pedal.

It was getting dark so we had to stop, but we'll be going around and pulling all the drums, checking adjustment, and then bleeding each one again to be certain the air is out of the system.

Many thanks to all who replied and offered suggestions.

 

[Davea Lux]

Update...
First checked fluid level and brake function with the engine on/off. Nothing changed. Nope, it didn't magically fix itself. Dang.

Decided to pop passenger rear drum off and have a peek. Wheel came off easy---turns out 3 of 5 wheel studs are stripped (wish I hadn't seen that). Much to my surprise I didn't have to fight getting the drum off. There was no ridge on the drum---looked like it was freshly turned---and shoes,plates/springs/etc were in great shape. I turned the adjuster out a few clicks to take up some slack so I had just had the slightest bit of resistance when I put the drum back on.

With about 3 foot of clear tubing on the bleeder, the kid pumped the brakes up and I cracked the screw loose. We did this 3-4 times with no bubbles, just a nice solid column of brake fluid. Pulled the drum off and no leaks. Put it back on and figured since I was already dirty and rolling among the leaves and ticks, I might as well double-down and bleed it again. About the 3 time I noticed some small bubbles in the hose and then on the next try, a long stream of air. It took several more cycles to get back to solid fluid.

At that point, the pedal was very firm (no need to pump), so we started the engine and...Gordon Bennett!!!! Solid pedal.

It was getting dark so we had to stop, but we'll be going around and pulling all the drums, checking adjustment, and then bleeding each one again to be certain the air is out of the system.

Many thanks to all who replied and offered suggestions.

If the pedal goes away again after sitting overnight, there is a leak someplace. There have been some significant problems with ChiCom wheel cylinders having poorly machined seats for the bleeder screws. This causes air to be drawn into the system causing erratic or no pedal condition. Sometimes there will not be an obvious leak at the bleeder screw unless there is a lot of pressure applied to the pedal.

Dave

Dave

 

[57fury440]

I'm betting it wasn't bled enough and the brakes needed some adjustment.

 

[Project Sketchy]

It definitely had air in the line---despite about 18oz of fluid bled through the new master cylinder and lines the first time. I don't see any leaks, but its first trip is going to be a short one around the neighborhood, culminating in some hard stops on an open parking lot and a careful examination for leaks. One only needs to survive the "OH NO NO NO!" experience of failed brakes just once to fully appreciate their importance.

 

[3175375]

Make sure that your emergency brake is operating correctly!

 

[1970FuryConv]

Update...
First checked fluid level and brake function with the engine on/off. Nothing changed. Nope, it didn't magically fix itself. Dang.

Decided to pop passenger rear drum off and have a peek. Wheel came off easy---turns out 3 of 5 wheel studs are stripped (wish I hadn't seen that). Much to my surprise I didn't have to fight getting the drum off. There was no ridge on the drum---looked like it was freshly turned---and shoes,plates/springs/etc were in great shape. I turned the adjuster out a few clicks to take up some slack so I had just had the slightest bit of resistance when I put the drum back on.

With about 3 foot of clear tubing on the bleeder, the kid pumped the brakes up and I cracked the screw loose. We did this 3-4 times with no bubbles, just a nice solid column of brake fluid. Pulled the drum off and no leaks. Put it back on and figured since I was already dirty and rolling among the leaves and ticks, I might as well double-down and bleed it again. About the 3 time I noticed some small bubbles in the hose and then on the next try, a long stream of air. It took several more cycles to get back to solid fluid.

At that point, the pedal was very firm (no need to pump), so we started the engine and...Gordon Bennett!!!! Solid pedal.

It was getting dark so we had to stop, but we'll be going around and pulling all the drums, checking adjustment, and then bleeding each one again to be certain the air is out of the system.

Many thanks to all who replied and offered suggestions.

Congrats! I think you're on the right track!

 

[TheRamManINC]

The 67 Newport has been sitting for about 10 months. Got in, started her up, pushed in the brake pedal and it went right to the floor (and then made an odd growl almost like anti-locks will do). A sideways glance at the brake-fluid level confirmed what we already knew but were trying not to think about....the master cylinder was leaking. So, rebuilt the master cylinder, bolted it back up and proceeded to bleed the master and then the system with the youngest kid pumping the pedal while I cracked open the bleeder at the wheel cylinders. The bubbles stopped coming out but it still took a couple of pumps to get the brake to feel solid. We were happy and expecting to celebrate with a few burnouts in the driveway...BUT...as soon as we started the engine, the pedal went immediately to the floor. No resistance at all. Nada. Nothing. Zilch. No leaks we can see. Turn off the engine, pump the pedal a few times and it has firm resistance again. Ideas?