Strange issue with my brakes

[Walker_Bulldog]

Well when I got the truck the brakes didn't feel right at all, the pedal would only move about an inch before getting rock hard. Also it wouldn't return to the top. I jacked it up and one of the tires wouldn't budge so I replaced both front hoses and calipers. That fixed my brake drag but not the pedal return issue. Before the new hoses and calipers the pedal would act the same with the engine running or not, after the new parts the pedal won't return only when the engine is running. Once I shut it off and I pump the pedal twice it returns like it should.

After reading a few threads I decided to check the prop valve reset pin. It was sticking out, I pushed it and after hitting the brakes it pops back out. There was no change in the pedal with the pin in or out. Bad booster maybe?

I have no idea what the problem is, and if anyone could steer me in the right direction I would greatly appreciate it.
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[LockDoc]

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It sounds like your return spring is either broken or missing. One end of it fastens in a bracket right by the brake light switch and the other end fastens up by the firewall. It will be white or blue in color.

LockDoc

[Walker_Bulldog]

The spring is attached and doesn't appear to be broken, I also looked over all the linkages and found no binding. I will check the spring again in the morning when I have some more light. There is no pressure on the pedal for the first couple inches when it's running but when it's not running the pedal has pressure for all of the stroke. It's making me crazy!
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[cpisani70@aol.com]

What is the condition of your back brakes. I have a new to me 71 C-20 and when I first got it I did front brakes seemed to stop a little better but not great and pedal was lousy once I did complete back brakes and I mean complete I replaced everything , truck stops great and awesome pedal . Just my two cents
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[Walker_Bulldog]

I have not had a chance to inspect them throughly yet, I got hung up on them feeling fine while it's not running and bad when it is. I will look at them tomorrow as well. Thing is I don't know much about drum brakes. Anything specific to look at that could cause the issue I've described?

[cpisani70@aol.com]

Drums can be a little tricky if you are new to them. I would suggest everything new drums,shoes,hardware and wheel cylinders it really makes a big difference . My advice would be to leave one side together for reference if you are worried and you can always take lots of pics with your phone to help with reassembly.
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[Boog]

I'd look at the booster and bracket mounting under the hood where the linkage goes through the firewall. Make sure it is not binding there. And is there any brake pedal freeplay?

[jocko]

Sounds like a failed master cyl. Sometime the power piston will hook on a slightly scored step in the piston bore. So, when you push it will go to a point, then stick (the piston in the bore, that is). Not 100% positive. but I had a similar issue - my brakes almost completely locked up at approx 2/3 pedal depression (thankfully in my driveway!). The pedal still moved because the spring will cause the pedal to return, but here are the symptoms to look for:
- Pedal will move with seeming LESS pressure than normal until the pushrod re-engages the stuck piston
- Will feel like you are driving with dragging brakes - like letting out the clutch with the parking brake on...
- pedal will likely be hard, once it's depressed to where the pushrod engages the piston.

my 2 cents! Good luck.

EDIT: If you have a booster to pedal connection that is a rod end, then the pedal will also hang up until the piston pops loose in the stuck master. My experience was wit NON-power brakes, so not certain this can translate to your situation, but technically, it could I believe.

[Walker_Bulldog]

There is about 1/4 of freeplay in the linkages when it's not running and about half of the pedal stroke is freeplay when it is running. The spring is definitely not broken and there is no binding at the firewall.
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[Walker_Bulldog]

I have a spare master cylinder so I will bench bleed it and swap them out.
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[midniteblues]

Check your booster to see if its holding vacum pull the hose too see if gushes air when the engine isnt running.other wise I would suspect the mc

[Walker_Bulldog]

I ran the engine for thirty seconds, shut it off and waited ten seconds before pulling the vacuum line and air did come out. I'm bleeding my master cylinder right now.
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[LockDoc]

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I was having similar issues with my Suburban and discovered that all of my rubber flex lines were collapsed on the inside, restricting fluid flow and causing a hard pedal. I also couldn't get much fluid out of the bleeder screws when bleeding the brakes. Replacing all of the rubber lines solved my problem.

Just a thought.

LockDoc

[Walker_Bulldog]

I thought the hoses were the cause at first so I replaced them. I just got the new MC on and the system bled. The problem remains:-( Should the booster hold pressure indefinitely? If I pull the vac line off after a couple minutes no air comes out.
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[fastwillie 696969]

Originally Posted by Walker_Bulldog

I thought the hoses were the cause at first so I replaced them. I just got the new MC on and the system bled. The problem remains:-( Should the booster hold pressure indefinitely? If I pull the vac line off after a couple minutes no air comes out.
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1


Depress the brake pedal repeatedly with the engine off.

2


Continue to hold the brake pedal down and start the engine. The brake pedal should be pulled down slightly after the engine starts. A problem with the brake booster or the vehicle vacuum system is indicated if the pedal does not pull down slightly.




3


Connect a vacuum gauge to the hose from the engine to the brake booster and start the engine. A reading of 16 inches or more of vacuum rules out a problem with the vacuum system and indicates the need to replace the brake booster.



Read more: How to Check a Brake Power Booster | eHow.com http://www.ehow.com/how_5701034_chec...#ixzz1qL2i0GMV.

[Walker_Bulldog]

Originally Posted by fastwillie 696969

1


Depress the brake pedal repeatedly with the engine off.

2


Continue to hold the brake pedal down and start the engine. The brake pedal should be pulled down slightly after the engine starts. A problem with the brake booster or the vehicle vacuum system is indicated if the pedal does not pull down slightly.




3


Connect a vacuum gauge to the hose from the engine to the brake booster and start the engine. A reading of 16 inches or more of vacuum rules out a problem with the vacuum system and indicates the need to replace the brake booster.



Read more: How to Check a Brake Power Booster | eHow.com http://www.ehow.com/how_5701034_chec...#ixzz1qL2i0GMV.

The pedal does move down after starting, following the steps you outlined. Now The BRAKE light on the gauge cluster is always on until I push the pedal, then it turns off. It comes back on when I release the pedal.
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[Walker_Bulldog]

Damn I feel like a fool. After everything I've done so far I decided it was time to work on the rear drums. Everything on the drivers side rear looks as it should. The passenger side however is missing one major component... The f***ing drum isn't there. Somehow after all the time I've spent underneath the truck I missed one of the most obvious things possible. I've never had that wheel off until today. I ordered one and I won't get it until tomorrow and I won't be able to install it until Thursday. Hopefully this is the last thing I need to fix the brakes.
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[slikside]

Originally Posted by Walker_Bulldog

Damn I feel like a fool. After everything I've done so far I decided it was time to work on the rear drums. Everything on the drivers side rear looks as it should. The passenger side however is missing one major component... The f***ing drum isn't there. Somehow after all the time I've spent underneath the truck I missed one of the most obvious things possible. I've never had that wheel off until today. I ordered one and I won't get it until tomorrow and I won't be able to install it until Thursday. Hopefully this is the last thing I need to fix the brakes.
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LOL! I'm sorry man. Sounds like something that could happen to me! I have some brake issues going on myself....so I hope your discovery helps solve your problem. Good luck, and let us know how it turns out.

[rsavage]

I would check the wheel cylinder carefully on that side as the cups have probably exceeded their normal range of motion due to no drum to stop the travel. Pull the rubber boot off the end of the wheel cylinder without disassembling anything and see if there is fluid behind the boot. If so, it needs replacement

[Walker_Bulldog]

There is no leakage from the cylinders at all. Waiting on the drum has given me time to replace both of the u-joints on the rear drive shaft so today won't be a total waste lol. They looked like they had never been replaced. Now I need to do the wheel joints and the front u-joints.
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[Walker_Bulldog]

On a side note, this drive shaft looks way weak. At the end that bolts to the output shaft it tapers down to one inch from four and a half. I doubt it would be able to handle much torque.
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[Walker_Bulldog]

New drum fixed the problem! Now I need to figure out which seal on my engine is leaking and I need to find a transmission shop. My transmission is bleeding fluid into the transfer case and it's leaking from somewhere else. Thank you all for your help!
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