Jump to content

Proportioning valve, Master cylinder - no pressure???


zeitgeist57

Recommended Posts

So after leaving both front brake lines disconnected from the calipers last week when I swapped them out with new calipers, I put the brakes back together on my 1982 Ford F100 and try to bleed the system. Pedal has a little pressure, but goes straight to the floor. Started up truck and drove it a few feet, pressed brakes to the floor, still coasting: absolutely no front/rear brakes. Needed emergency brakes to stop.

 

1) Tried pumping the pedal, to the floor...no buildup of pressure.

 

2) Used my HF pneumatic bleeder to suction out air/fluid at the calipers. No luck on either caliper. Have not tried the rear drum brakes, but if fronts don't work no need to do the rears yet.

 

3) Borrowed Motive Power Bleeder. Got master brake reservoir up to 15psi. Cracked a caliper bleeder. No release of any pressure. Totally removed bleeder from caliper, no pressure release.

 

I cracked a like at the proportioning valve. NO RELEASE OF PRESSURE. I mean, c'mon!!! :mad: Nothing?!?! What am I missing here? I can't bleed a dry system with a full reservoir that doesn't want to bleed fluid anywhere...

Link to comment
Share on other sites

Yes, new calipers. Bleeder valve broke off in one of the calipers so I replaced them. As it sits now, caliper pistons are totally backed off (out of the box) and they wiggle on their brackets. No matter how much I pump the pedals, there is no pressure going to any of the brakes.

 

The thing that totally baffles me is if I pull one of the front brake outlet lines from the prop valve, it's totally dry and no pressure is bled out of the master cylinder....

Link to comment
Share on other sites

So you're saying you pulled the line from the master to the prop and no fluid?

 

You can try pump hard and fast (stomp on it hard) on the brake pedal, sometimes if something is stuck that will free it up.

 

Or open the rear bleeders and stomp on it.

Link to comment
Share on other sites

So you're saying you pulled the line from the master to the prop and no fluid?

 

You can try pump hard and fast (stomp on it hard) on the brake pedal, sometimes if something is stuck that will free it up.

 

Or open the rear bleeders and stomp on it.

 

No. There's fluid. When I crack the lines from the master reservoir to the prop valve fluid definitely comes out.

 

I'll stomp on it a few times. I worry that when I used a C-clamp to back up original caliper pistons I pushed old brake fluid/water/gunk into prop valve. I did that first, to get old calipers on, and then ended up swapping to new calipers when the bleeder valve broke.

 

Did the master cylinder and lines bleed out when you were swapping calipers when you had the lines off?

 

No, the lines bled a bit when they were off, but the master cylinder had plenty of fluid.

 

Did you replace the master cylinder? Are you sure everything is connected (from the pedal to the MC)?
No replacement of MC. If this stumps me a bit tonight, I'll disconnect the MC to see the condition of the brake booster and linkage to pedal. When I had the reservoir lid off, and I pumped the pedal lightly, I could see squirts from the front reservoir fluid level (front brake circuit)

 

Sounds like the master went dry and you need to bench bleed it..

 

Then start at the RR then LR then RF then LF

 

If that's the case, Rocky...wouldn't 15psi with a Power Bleeder on the reservoir be enough pressure to start bleeding out the old fluid and air bubbles?

Link to comment
Share on other sites

No. There's fluid. When I crack the lines from the master reservoir to the prop valve fluid definitely comes out.

 

I'll stomp on it a few times. I worry that when I used a C-clamp to back up original caliper pistons I pushed old brake fluid/water/gunk into prop valve. I did that first, to get old calipers on, and then ended up swapping to new calipers when the bleeder valve broke.

 

 

 

No, the lines bled a bit when they were off, but the master cylinder had plenty of fluid.

 

No replacement of MC. If this stumps me a bit tonight, I'll disconnect the MC to see the condition of the brake booster and linkage to pedal. When I had the reservoir lid off, and I pumped the pedal lightly, I could see squirts from the front reservoir fluid level (front brake circuit)

 

 

 

If that's the case, Rocky...wouldn't 15psi with a Power Bleeder on the reservoir be enough pressure to start bleeding out the old fluid and air bubbles?

 

Not necessarily. I doubt pushing the calipers in caused dirt to be stuck.

 

You have to start from the beginning which is the master. Once you get fluid coming down the lines good move to the wheels. A pressure bleeder doesn't work in all cases. Sometimes you have to go old fashioned and use 2 people.

Link to comment
Share on other sites

You could try the old fashioned one man bleeder. Attach a piece of tubing to the bleeder and submerge the other end in a bottle with a little clean brake fluid. Then you can just keep pumping the brakes. Submerging the tube in fluid prevents it from sucking air when you release the pedal. Sometimes works better than power or vacuum bleeders.
Link to comment
Share on other sites

SUCCESS

 

Big thanks to everyone who posted in here. :thumbup::leghump:

 

- I slammed on the brake pedal a bunch of times like a madman (figure if there is something weak/damaged, it'll break. Otherwise, can't hurt) and it built up a little pressure. Hooked up the Power Brake Bleeder, and used my HF pneumatic bleeder nipple, line and catch can at each wheel. At first, I cracked the RL drum and it was very slow and bubbly. I kept the bleeder screw open and railed on the brake pedal a bunch of times (Mark's suggestion, since it's hooked up to a line with fluid in can) and it became firmer. Go back to RL, and fluid and bubbles coming out much better.

 

- Used a "one man brake" process of open, let fluid and bubbles escape, close (with nipple-and-catch-can attached to the bleeder) pumped up pedal, and cracked the lines. I didn't mind the repetition at all, because the fluid in the catch line made me confident I wasn't introducing new air into the system, only releasing fluid and trapped air in the lines.

 

- Did RR, LR drums. Started Cleetus and drove a few feet. Pressed pedal. BRAKES IN REAR. :D Pedal still spongy...

 

- Jacked up RF, bled caliper. Pedal much firmer, slack in caliper taken up. Repeat for LF caliper.

 

- Started Cleetus and enjoyed the firmest brake pedal I've experienced in one of my tee-ruks for as long as I could remember. My old diesel Chevy Cleetus sprung a leak in the master cylinder/reservoir, and after I repaired it it was always kind of spongy. I must not have bled it properly. These brakes are incredible.

 

- Drove Cleetus to 25, 35, 45mph intervals, stood on the pedals. NO TIRE LOCK, very controlled, firm, and stopped waaaaay shorter than before. Given that the houses in my neighborhood sit on appx 100ft wide lots, I was stopping from 35mph in about half a property line...50ft or less?

 

Anyway. THANK YOU THANK YOU THANK YOU for the suggestions. I am not an engineer and I sometimes try to "talk" my mind away from a car problem: "No, it can't be something simple! Must be a catastrophic problem!!!1!1" :lol:. There must've been a massive amount of trapped air in the master reservoir (ROCKY!) and pumping with the pedal very hard produced enough pressure to jump start the bleeding. It's great to get some great suggestions by awesome guys on CR. Couldn't have done it without you all!!!

 

Getting aligned tomorrow and Cleetus is ready for cruising and more work! :fuckyeah:

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...