Brake repair i have a 1985 chev 1 ton truck the brakes have to be pumped to stop .have replaced ,master cyl,wheel cyl's new back shoes,new front pads,booster is ok.

Does the car have ABS ? And does it have an equalizer block for the 4 wheels ?
It sounds like the ABS has been affected, or there is an equalizer block that is stuck on the front wheels only.
Can you open the bleeder or the rear line on the master cyl and get fluid to come out by depressing the pedal ?

Replace master cylinder, do not use kit, master cylinder bores are probably scored.

Dont try to repair the wheel cylinders. It is much easier and not expensive to replace them . new ones are available from an aftermarket auto store. Do one side at a time so you can refer to the unstripped down side if you cant work out how it goes back together. Place a clamp or locking pliars on the rear flexible brake pipe to stop loosing all the brake fluid when the cylinders are removed. Remove the shoes and cylinder , Fit new cylinder, replace the shoes if they are soaked in brake fluid or badly worn. When you have done both sides bleed and sdjust them. make sure you top up the master cylinder with brake fluid. If this is helpful Please Vote Jeff

if it is the wheel cylinder that is leaking then it will have to be replaced and all the components cleaned with brake cleaner.depending how badly soaked the brake shoes are you may have to replace them also.you may have to heat the brake line that connects to the wheel cylinder,or even replace the line if it gets damaged.the bleed all the air out of the system,

Bleed front more. If needed, remove line from each front caliper to ensure fluid is flowing. If no fluid movement you may have a bad master cyl.

YOU NEED REMOVE A LITTLE BRAKE FLUID FROM MASTER CYLINDER.THEN YOU RAISE VECHICLE SAFELY.SUPPORT IT WITH JACK STAND.MAKE SURE VECHICLE IS ON LEVEL SOLID GROUND.REMOVE TIRE OR WHEEL.THEN YOU NEED A LARGE C - CLAMP.PLACE C - CLAMP OVER BRAKE CALIPER AND BRAKE SHOE BACKING.TIGHTEN C - CLAMP JUST ENOUGH PUSH CALIPER PISTON BACK IN CYLINDER BORE TO REMOVE CALIPERS FROM ROTORS.TO REMOVE BRAKE CALIPER YOU NEED 2 OPEN AND BOX END WRENCHES ONE TO HOLD CALIPER SLIDE PINS AND THE OTHER WRENCH FOR LOOSEN CALIPER BOLTS.THEN YOU REMOVE CALIPER AND REPLACE FRONT BRAKE SHOES.IF YOU NEED TO REMOVE BRAKE ROTORS JUST REMOVE THE BRAKE CALIPER CARRIER SUPPORT BOLTS THE REMOVE THE BRAKE CALIPER CARRIER SUPPORT THEN REMOVE ROTOR.YOU NEED TO REPLACE BOLTS WITH NEWS AND USE LOCK TIGHT.THEN YOU PUT IN NEW BRAKE PADS IN CALIPER PUT CALIPER BACK ON SUPPORT CARRIER.REPLACE WITH NEW BOLTS USE LOCK TIGHT THEN TORQUE BOLTS TO 26 FT LBS.MAKE SURE MASTER CYLINDER COVER IN PLACE.WHEN YOU FINISH REPLACING BOTH FRONT BRAKE PADS PUMP BRAKE PEDAL TO SEAT BRAKE SHOES AGAINST BRAKE ROTORS SO YOU WILL HAVE FIRM BRAKES WHEN YOU APPLY THEM. THEN CHECK YOUR BRAKE FLUID LEVEL IN MASTER CYLINDER MAKE SURE ITS NOT LOW. MAKE SURE YOU HAVE FIRM BRAKES BEFORE DRIVING.IF YOU HAVE ANY PROBLEMS CHANGING FRONT BRAKE PADS YOU CAN GO TO ANY AUTO PARTS STORE AND BUY A HAYNES REPAIR MANUAL.

that sounds just like a leaky none return velve in the master cylinder or very low on brake fluid it may even have got air in the system also if you removed the rear drums and never ajusted up the brake shoes this could give you this problem check the rear brums first the brake shoes should just be tuching the drums if there not pull off the drums and wind up the ajusters then refit the drum till the drake shoes are only just clearing the drum i know they have self ajusting shoes but half the time they just dont work very well so ajust it by hand,, the front brake are disk's and they are self ajusting,,,
after doing this work leave the car for a minue or so and stamp on the brake to pump them out if you then need to pump the brakes up again that shoes its just ajusted the rear drums,,,the brake pedel should only ever need to be prest once never pumped up,, if this dont help you out and sort out the problem then and only then replace the master cylinder as there normaly very strong and dont brake down often and they often leak brake fluid first,,,my bet is its the rear shoes needing ajusting up

Hello,
I hope this helps.







Thank You,
Roy

Sounds like your master cylinder is shot. Go to a parking lot, stop, and pump the pedal a bunch of times. Then get out and see if there is any fluid leaks by any of the wheels. That would indicate a brake line leak. My first guess, however, is your master cylinder.

Did u replace all the brake lines, front and back brakes replaced? Make sure u did the following:
1. make sure master cylinder is topped off (full)
2. go to the bleeder the greatest distance from the master cylinder, Have someone pump the brake pedal 3 times, each time about half way down w/ pedal, on 3rd pump, they should depress the pedal half way and hold it there while u open the bleeder. When air or fluid comes out and it begins to slow, gently snug the bleeder valve shut before the pedal is released. Continue to do this until only clear, clean fluid is flowing. Keep checking the master cyl. level, if u let it go down too much u will **** air into the line and have to start all over. Go to the next bleeder that is farthest away, etc. til u do the closest bleeder. Car should be running doing this, and you MUST use safety stands so u don't have the car falling on u while u work under it. Also make sure all your new brake line connections are tight, or it will allow air into the lines. Let me know how this works for u. good luck countrycurt0