Brake advice on a 1996 chevy Silverado 4x4

How do I tell if the master cylinder is bad? I recently found where whne my dad had the truck he had midas replace the brakes. There was somethign about a master cylinder which he "declined".

a spongy feel usually means air is still in the lines. You could just gravity bleed the system, or do it the old fashioned way

How do I tell if the master cylinder is bad? I recently found where whne my dad had the truck he had midas replace the brakes. There was somethign about a master cylinder which he "declined".

******** Pump up the brakes and hold them. If the pedal begins to creep to the floor, that is a very good indication the master cylinder is toast.**

By the way, you said you had rear drum brakes. You dont replace pads on drum brakes.. You replace "shoes".

You probably already know this, but dont work on one side without doing the other side as well.

Finally, where did you find the brake fluid leak?? On the slave cylinder boot at the rear drum brakes? If, as I suspect, it is the slave cylinder, then you may have just pumped the piston out too far when you were replacing the shoes and caused a temporary leak, ** OR you have a corroded and leaking rear slave cylinder. Did you rebuild the cylinder, hone it, replace the rubber parts, pistons, or ???

Thanks so much for your reply.

I know you are supposed to replace both "shoes" but I ran out of time. I hope this is ok to just delay a week. SHoudl I also have the drums resurfaced? On the one side I replaced the shoes and all the springs. Plan to do the same to the other side.

I did not replace any wheel cylinders. I had to force the shoes on because of the spring tension. Where the shoe contacts the rubber boot I saw oil dripping down. I have checked under the vehcile after drivign and parkign overnight and see nothing ont he ground. Could this cylinder be ok? I really dont want to replace it. My manual says the shoes have to come back off and I had a heck of a time getting them on there.

FWIW by the way my emergency brake is not working very good. (It started several weeks before I even attempted to replace shoes.)

Do I pump the brakes with engine on or off?

Thanks so much for your reply.

I know you are supposed to replace both "shoes" but I ran out of time. I hope this is ok to just delay a week. SHoudl I also have the drums resurfaced? On the one side I replaced the shoes and all the springs. Plan to do the same to the other side.

******It can be really dangerous to "repair" one side only and drive with it. You are taking your life in your hands when you do this.

You can look at the condition of the drum surface and decide whether it needs to be resurfaced. If it is heavily grooved, then it much be turned or replaced. For minor scratches, you may get by without it, but DONT resurface one and not the other.

******** Could this cylinder be ok? ********* Yes, it could be okay...or not. I assume you bled the brakes and went through the preliminary adjustment of the shoes?

********* FWIW by the way my emergency brake is not working very good. (It started several weeks before I even attempted to replace shoes.)

********* When you finish the other side, and have bled and preadjusted the shoes, then you can work on the parking brake. There should be a place where the cable from the parking brake pedal or lever can be adjusted.

*******

Do I pump the brakes with engine on or off?

******* Pump up the brakes with the engine running so that the vacuum assist will work. Hold them in hard and see if the (usually after a short pause) pedal seems to release and move toward the floorboard. If it does, you can be almost 100% sure the master cylinder (under the hood) is faulty.

Doesn't sound like you need the drums resurfaced. It sounds like your old shoes needed replacing because they got old rather than worn.

They make a pliers like tool for installing and removing the springs that makes the job pretty easy. I don't think they cost that much.

Try it both ways. When the engine is off the pedal should feel like it is higher and harder than when the engine is running.

Pumping the brakes shouldn't make any difference (after you depleted the booster vacuum) unless there is air in the lines or the rear brakes are not adjusted correctly. I think the point was does pumping the brakes and holding get rid of the spongy brake feeling? Does the pedal hold steady or does it sink slowly when you hold the pressure?

-jim

Is it possible for the cylinder to leak like it did only temporarily?? No I did not bleed the brakes, I never took anythign off other than the shoes. My manual did not say anything about it. SHould I have?

I drove in reverse and applied the brake several times to adjust them. Was that right?

You should if they need it. Are they scored, out of round, rusted, heat checked?

That would be a good idea.

"Force?" WTF? This style of brakes has been around for a long-long time, the proper tools required are readily available.

You have a leaking wheel cylinder. I either needs to be rebuilt or replaced. The leak is very likely to be the source of the spongy brake pedal.

"OK" wheel cylinders do not leak fluid.

Too bad.

If you really believe that to be true, then you lack ingenuity in addition to the proper tools. So, either figure it out or buy the right tools.

That's not much information to go on.

Answer best left to if and when you manage to recognize and perform the needed repairs.

In your dreams...

It is not mandatory to bleed the wheel cylinders, nor is it necessary when one is merely replacing brake shoes unless there is another problem that requires attention.

Dunno... did you inspect, clean and lube the adjuster mechanisms when you had everything apart? 'cuz it's entirely possible after 300K miles that the adjusters are seized solid and all the backing and braking in the world won't do a damn thing.

Is it possible for the cylinder to leak like it did only temporarily?? No I did not bleed the brakes, I never took anythign off other than the shoes. My manual did not say anything about it. SHould I have?

****** The wheel cylinders can leak when you are trying to get the shoes held down, get the actuating rods back between the shoes and the pistons in the cylinder, etc. This is because the pistons inside the cylinders can be pressed too far to one end or the other of the cylinder bore, and some fluid could leak out. This, in itself, is not a serious problem if you get them back like they should be AND if they are not corroded and leaking.

If you could have a person who knows how to reassemble the rear drum brakes help you do this just once, you would find it a lot easier next time.

*******

I drove in reverse and applied the brake several times to adjust them. Was that right?

****** Normally, you pre-adjust the rear brakes before you go through that step.

If the brakes are too far out of adjustment, the autoadjusters will not activate properly on backing up and you will have a problem.

To do this, you put the drum back on. Then, there is usually a hole in the backing plate of the rear brake assembly through which you can insert a tool and advance the starwheel until almost all the slack is taken out of the braking system...The tool required looks a little like a flatblade screwdriver, and a fine blade screwdriver has been used millions of times to do this job.

Jim refers to tools required to do this job.. I have never found a use for the special brake pliars that are often advertised and are found in FLAPS.

There is a special tool used to put the retainers on the hold down rods that is helpful, but this job can be done with a regular set of pliars, with a little practice..

There is also a special tool that can be used to remove and replace the springs and, to me, this one IS helpful, but you can do the job, if you are strong, with a set of diagonal cutters...They allow you to get a good grip on the springs and - despite what it sounds like - they do not damage the springs.

If a car is getting old, I would at least inspect the wheel cylinders. I would guess that not too many people rebuild them nowadays because they are normally fairly cheap to replace.

BUT if you want to replace them, be careful and do not booger up the brakeline nut that screws into the old ones when you try to replace them...Use a "line wrench" - not a Crescent nor even an open end wrench.

One last thing...did you take the adjusters apart, clean them in solvent, and re-lubricate them before you put them back on? You want to be sure those adjusters move freely. Nota Bene: The adjusters on the left side are different from those on the right and they are not at all interchangeable. You dont have to worry about this since you did only one side, and there should have been no chance you would get the wrong one on the wrong side.

I did take the adjusters apart, cleaned them, and re greased them. I also installed new springs.

There was no oil on either wheel cylinder when I took the drums off. I am hopng the fluid does not mean I damaged the cylinder.

I used the other wheel to copy the pad and spring placement on the wheel I was workign on. (drivers side).

I am going to double check but I feel the master cylinder probably needs replacing. Is this hard? I know how to bleed brakes and I have a vacuum pump from harbor freight for brakes. But, it seems someone said they had to bleed there abs too? Is that necessary and how is that done?

I just worry thinking this will be a quick repair with the mast cylinder and doing somthign like breaking off a bleeder screw or something.

I really appreciate your patient and help!

There was no oil on either wheel cylinder when I took the drums off. I am hopng the fluid does not mean I damaged the cylinder.

****** You didnt damage the wheel cylinder...Sometimes they will dribble a little IF you move the pistons too far to one side or the other...as you might do if you are fighting the brake springs. But, if you got them back together properly, and if they were ok to begin with, there should be no residual problem.

As Aarcuda says, these things dont leak a little and then stop IF they are corroded or have the rubber parts damaged. With a vehicle as old as yours, and with as many miles, I would have at least inspected the cylinders, if not just replaced them automatically.

******** ******** I used the other wheel to copy the pad and spring placement on the wheel I was workign on. (drivers side). ******** Fair enough, but you still dont have pads ;>).

Until you get more experienced, I would suggest that you make a little drawing of systems that can be confusing...Note where springs attach, the sequence of washers, springs, bolts etc. Or even make a picture with your digital camera in case you get confused later..

******** I am going to double check but I feel the master cylinder probably needs replacing. Is this hard? I know how to bleed brakes and I have a vacuum pump from harbor freight for brakes. But, it seems someone said they had to bleed there abs too? Is that necessary and how is that done?

****** If you have ABS, special bleeding techniques may be required. Look them up in your book.

Now, it is normally not too hard to change out a master cylinder. Again, use proper "line wrenches" ,when needed, not visegrips or water pump pliars, or crescent wrenches.

******* I just worry thinking this will be a quick repair with the mast cylinder and doing somthign like breaking off a bleeder screw or something. *******

Sometimes breaking something is inevitable. We have all done it. There is no hole I have ever seen that is too deep to climb out of.

Minimize the likelihood by using the proper tools and using them only for what they were made for. Go easy....Some people have problems remembering what direction you turn normal bolts or bleeders to get them off...other people come by this naturally. Lots of people have twisted off nuts and bleeders thinking they were loosening them when indeed they were torqueing down on them. Think twice, act once carefully.

Now, IMO, brakes are something that must be done correctly because your life is riding on them. That doesnt mean that you have to replace every part, every time, or go overboard. As you gain experience you will learn what is critical and what isnt.

If I were near enough, I would drive up and help you with this.

I noticed your dad declined installation of a new master cylinder. This indicates to me that he either knew enough to think that this was unwarranted, OR, he didnt want to bite the bullet on price.

If your dad is still alive, maybe he can help you. Or, if you are in East Texas, let me know where and I will see if it is convenient for me to drive there and get you through this.

Here ya go, The pros do it and make it look easy....

More of a shade tree actual world weekend way to do it, Lots more videos about brakes. BTW I went through a stop sign and then through a fence once because I didn't bother to fix a leaking wheel cylinder and I was going to get around to it later but never did, no warning, brakes went right to the floor. That was back in the old days, an older car with only a single hydraulic braking system. I think it was a 62 Comet.

Thanks so much for the offer! But I am in Kentucky, not real close!

I cant really tell if it is the master cylinder or not. I did notice that oil seems to be leakign where the master cylinder connects to the vacuum booster. I dont know if it just started this since I have been workign on the breaks or if it has always been this way. Once I get the other pads on on fix the emergency brake I may just replace the master cylinder and the vacuum booster. The master cylinder is 29 bucks at autozone with a lifetime warrently. The current vacuum booster I put on last year was a lifetime warrently unti from autozone. So it would cost me nothing to bring it back. Just alot more work.

I looked I do have a vacuum pump for bleedign brakes although I have never used it.

I cant really tell if it is the master cylinder or not. I did notice that oil seems to be leakign where the master cylinder connects to the vacuum booster.

******** So the pump up test proved nothing?

Have you noticed that you had to add brake fluid to the master cylinder reservoir occasionally?? If so, it had to go somewhere. Often you can smell it inside the cab of the truck if it is leaking.

But, a master cylinder doesnt have to be leaking to be bad. There are other modes of failure.

Get your brakes fixed first, and do them right. After you are sure they are right, you can attack the parking brake adjustment and determine whether you need a master cylinder.

A few other things:

For some reason the pedal pressure and brakes seems to act better/feel better when goign in reverse. WHy would that be?

Also, my truck does have abs but my manual says nothing about how to bleed the abs unit or even if it is required when replacing a master cylinder.

It also says for rear drum adjustment to jack up the rear end, install the drums wheels and tires, and use an "adjusting tool" to adjust the brakes until the wheel grabs, then to back off so it does not grab. What is this adjusting tool, one of those spoon loking things? Can I use a screwdriver? How to I get to it with the heel and hub on?

I am confused on the pump test. I pump them hard and it still feels soft but the pedal pretty much stays in place.

I have never had to add brake fluid really.