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No, it won't and that won't accomplish much of anything. It may already be too late for that system.
You need to use something to suck all the old fluid out, then refill the reservoir and bleed all 4 wheels until it flows clear at each wheel.

That has to be it. Check everywhere fluid goes on some schedule. Flex hoses, wheel cylinders etc.
What happens with master cylinders especially when older like this is when it travels down more than it might have in ages there is crust inside and the seals tear right up. It's actually good than it did that all at once and not in a panic stop on you,

T

Ok thanks a bunch, I know exactly where the master cylinder is, the brake booster, however might take a little bit of digging to locate. I will probably be picking up the parts soon.

Once again, thanks a lot!

Just looked -----

Booster: Available but special order.......
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Master cylinder: Available and special order too. Get the complete one with reservoir and cap. Neither were very pricey for this!
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Good luck with it,

T

So ive got the master cylinder coming later, as well as the brake booster. Going under the hood I see bolts connecting the brake lines, I see the hose that runs from the engine. Is there any really elaborate steps to remove these two parts or is it simply bolts and the vacuum hose?

Should be mostly nuts and bolts. Rusted anything could be a pest. Flare nut wrenches for lines. Hope info comes with parts but pay attention to vacuum booster if adjustable there doesn't need to be some freeplay before it pushes on master cylinder. If not brakes would not return fluid well or at all after applying brakes. Not sure if adjustable or the spec. Check at brake pedal now with a finger how much is almost nothing before resistance as a clue.

Bench bleed master cylinder first off of car. Instructions and probably a kit to help should come with new one. If not say so but basically you put lines in outlets while body of master is held in place like a vise and push on end that goes to booster returning fluid to reservoir watching for it to be free of bubbles.

If no kit in the box you could/should just get some short pre-made lines that fit and make your own.

Think about the check valve at the booster to toss that too along with the vacuum hose, clamps if needed.

Bleeders at all wheels need to work when all installed and finish with bleeding whole system. If you run into any problems just ask and someone here can dig out some details. It's possible to have something hard to get at for fasteners but I don't know of any special tools just for this job.

Take your time and find out what or why if it isn't going well. This shouldn't be that tricky as things go, just age on things,

T

the master cylinder is removed. I am not working on the brake booster. I have to disconnect the brake pedal from the booster. I have easy access to two screws, difficult to one screw, and one i cant even see.. Just trying to figure out how to disconnect brake pedal

Here's some procedures that I found out there. AYOR for accuracy. Getting to fasteners you can't even see is a pest. There will be a way to get at it.

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REMOVAL & INSTALLATION

1. If equipped with an air bag, disconnect the negative battery cable and properly disable the Supplemental Restraint System (SRS), as detailed in Chassis Electrical .
2. Disconnect the vacuum hose at the booster.
3. Remove the master cylinder. Plug the brake lines immediately. Place the master cylinder in a clean, protected location out of the work area.
4. Remove the brake pedal-to-booster link pin and the 4 nuts retaining the booster. The pushrod and nuts are located inside the vehicle under the instrument panel.
5. Remove the booster assembly from the vehicle.
6. To install, reverse the removal procedure. Tighten the 4 retaining bolts to 10 ft. lbs. (14 Nm).
7. Bleed the brake system.
8. If equipped, enable the SRS system and connect the negative battery cable.

4. Remove the brake pedal-to-booster link pin and the 4 nuts retaining the booster. The pushrod and nuts are located inside the vehicle under the instrument panel.

stuck here cant find pedal to booster link pin



Here is a possibly really stupid question, should the brake booster have brake fluid in it?

No, the booster holds vacuum to assist the braking action. The brake fluid that's in the booster now is what your engine was burning. That's why you are replacing it.

Re: Link pin: Couldn't find anything exact for a pic of what and how. Something holds the pushrod to booster from pedal from just flying around. Hitch pin, something acting as a cotter pin. Whatever way would be made to not just rattle loose.

Just an assortment of things may not be anything like any but the idea...........


Gotta find it and it must be in good shape for re-use.............MANDATORY!

T

I have it all disconnected.....now i cant seem to get it out. My engine bay is rather small, I cant even get the tip of the brake booster out. there is a tip that sticks out that I cant clear outtof the brake pedal area, does it detach? (the part that attaches to the brake pedal)

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That pic again. Is it the item to the right that has no clearance? Does the replacement have it in place same as old one? Smile but you are there and I'm guessing at what is in the way to jockey this thing out. What is in the way of pulling it straight forward then some angles now?

Where is the most problem, inside the car or outside under the hood. If engine itself is the stopper be sure if that's a last resort to tilt it or remove what is in the way. I'm at a loss without looking right at it as it is now. I'm not ready to say detach anthing that is on the replacement booster.

Note: I'm here a lot checking in but can't be watching all the time for question if you are waiting. Do think thru anything you may need to move out of the way such that you can put it all back properly. If brake lines are a problem from master those should have enough to flex out of the way but be sure when you hook those up they are not cross threaded into master before you tighten those up.

Keep looking at what and where the hold up is,

T

So everything is good, brakes are all done. Bled everything good brake pressure no loss of fluid. Now I am having problems with an unusually high idle, we had to move a bracket behind the carb to wiggle in and out the brake boosters. I am looking for the idle adjustment, I believe we may have tripped it in our work. I cant seem to find a diagram or a picture detailing what this looks like

Is the vacuum hose going to the booster securly plugged in at both ends? Do you hear any hissing noises?

Yes, its good. I am being led to think I need to adjust the idle.

See if pic shows direct......


So far that showed for me? Your choke is about where it would be about 10 seconds after you start it up cold as in on fast idle. The rod that goes to the choke thermostat you should be able to open choke fully to test for that binding. You would then need to hold throttle up some (all this engine off) and that choke plate should be free to move.

This is a mind game now - what temp was the engine at when you took that picture #2 on you list of them back a couple posts? If that choke in the black housing top left in that pic can't shut the choke off via electric heater probably or possible exhaust heat (doubt that for 1985) it's going to race like it's cold. In that the problem just started with this job my bet is it is electrically heated to shut it off and the choke plate would stand up wide open and all would be just ducky.

Many that are electric heated if you just put key to run without starting engine would heat that up to the touch from cold and shut or at least feel that housing warm to hot to the touch.

Check wire and that housing metal bracket is in fact ground -- that hoop that holds it in place.

If all confused and I can do that well go ahead and start it with as much connected as possible and push the rod to open choke, flick throttle and it should be on the old warm idle. If that works but won't do that automatically that choke got messed up. Best guess for now. If not that hit back and let's see what else it could be? It has to be something touched while doing the booster job,

T

Your post posted before I posted mine. If throttle cable doesn't allow carb to return to its base idle you will need to work on that. Careful of those things as if you get that wrong the other way when you put gas pedal to floor you are torquing on the carb and can bust it. You won't like the price of that!

T

Well next time I get a day off ill work on this throttle cable. I shall post a new topic when I get to it, I look forward to hearing your advice! Thank you. (ill go ahead and get it ordered)

Keep it here for now as a problem from doing the booster job. Again you are there looking so have the advantage. My caution about a throttle cable is that the carb itself is NOT supposed to be the stop if you understand me. If you have it just right the gas pedal would be hard to the floor (engine off) right at the point the throttle is wide open at the carb.

One more: If that choke never shuts off you'll have lots of problems from running way too rich,

T

Ok, so after having a my brother-in-law look at it, it appears that the throttle cable was partially messed up where it enters the engine bay (partly due to the massive bending and twisting required to move the master cylinder and brake booster into place). The idle has dropped significantly, still a little high. After burning off the brake fluid that had been previously dumped in the engine. Brakes are good, no fluid drop. Engine idles about 500-1000 higher than normal.

So here is the new and final question on the repair of this damn car.

Can you lower the throttle idle on the carb, as opposed to replacing the entire throttle cable? At this point its a matter of convenience, I DONT want to detach hoses and move this and move that.

This was definitely quite a job, and I am very very grateful for the help and advice yall have given me!

Thank you

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this is what im working with

Brake booster works by using engine vacuum assisting the master cylinder. When the booster fails as well as the master cylinder, that engine vacuum will allow the leaking brake fluid to enter it and be burned through the engine. Brake fluid inside the car justifies a bad master cylinder.

Those are classic symptoms of a master cylinder bypassing. The internal seals can't hold the pressure & since it's internal there is no fluid loss.

A power booster won't cause the pedal to go to the floor.. When they fail you lose you assist & the pedal is hard....

Hi Sidom, thanks again for your reply, so does this mean that I can just replace the master cylinder gaskets and my problem is solved or will it be easier to just change the whole master cylinder?

Although Sidom is right that the master cylinder is usually the cause, I have had 2 vehicles in the past month with the same symptoms that BOTH of them turned out to be debri stuck in one of the valves of the ABS unit. The way i cured it was to slam on the brakes on a gravel road so the ABS activates and clears the debri. I had already changed the master on both of these cars and still had the same problem until flushing the ABS valves this way. Pressure bleeding did nothing for the problem.

That's interesting Hammer.... I haven't run into that yet but I see where it can happen

Just a couple of quick questions on those....

Was the ABS light on? and Was it the same symptons as a bypassing master (sometimes a pedal, sometimes not) or was this like a total failure & just couldn't get the pedal back??

No ABS light. No brake light as long as the reservoir was full, although you could put the light on if you let the pedal drop enough.
It was EXACTLY the same as a bypassing master. One of the solenoids just wasn't closing all the way. As soon as I activated the ABS a couple times, the pedal got solid and no further problems. I had already replaced the master and flushed the system on both of them. No further bleeding was needed for either one also.
One was a GM and one was a Ford.

Take a screwdriver handle and rap on the side of the master cylinder. Sometimes when you run the fluid real low, the float will stick at the bottom. It can also be the parking brake partially on, air still in the system or a problem with the rear wheel ABS system with a stored code.Try unplugging the big flat ABS module to eliminate that.

i tried all above when bleeding i did see brake parking lite flicker then stayed on more air?

Make sure the master is full

John; Did the (I hope NEW) master cylinder come with the fluid level sensor? Is it plugged in?

the master had no sensor on it?

As I stated in my first response, your truck likely has rear wheel ABS and when it stores a trouble code, it puts that light on. Unplugging the module will put it out.

what plug is for module thanks unit on fender has three plugs on it ?

If it has it, there will be a flat module, probably mounted vertically, right near the master cylinder with one long plug.

John; For some unknown reason, my parts illuminator is out to lunch, right now. Thinking back, I'm not so sure those had a level sensor? May have steered you wrong? '92 with ABS? Could you verify the production date? Should be on a sticker on the driver's door.

hi i just replaced other side caliber bleeder froze and rebleed antibrake lite and p brake lite still stays on brakes fine master full ?