Master Cylinder

After changing both rear calipers, pads, and rotors, I cannot get the pedal on my sister's Maxima to stay up. I can bleed everything, get a good pedal, let it sit, and then the pedal is low again. I've been told to change the master cylinder, but I'd like a second opinion since its not my money.

The car is a '92 Maxima SE with 4 wheel disk brakes and no ABS. The fluid is new in the entire system, and it has been through about 3 quarts of fluid since I started bleeding. The pedal is high but spongey with the car off. With the car running, the pedal is about 2/3 of the way to the floor and still spongey. It will sink after only a few minutes of sitting.

not very helpful, but you're describing a system with air in it

That's what I thought, but I've bled it for at least 2 straight hours. I have nothing but clean, fresh fluid from all four wheels.

The only peculiar thing that I noticed was that working the e-brake a few times seemed to have an effect on the pedal. Could there be air trapped in the e-brake assembly inside the calipers? Is there any special way to release it?

no, there won't be anything special about the ebrake. You are pushing the pistons out, on the rear calipers when you apply the ebrake, and that changes how the pedal feels

You have air in the system, and you method for bleading the system is missing an air pocket. could be air at the master cylinder, or you might have air trapped in the ABS pump, or proportioning valve, or some other spot that is unfriendly. Sometimes you have to get creative on bleading systems

As a general rule, the master cylinder is a favorite spot for problems, but that usually only happens after running a master dry

The master and proportioning valve are a single unit with no ABS. We bled the lines at the master 3x per line. The master has not been bled with one of those kits with the lines that run back into the reservoir, but there was no air visible at the lines. I will look for a bench bleed kit at the parts store and try to bleed the master again tomorrow.

Any "creative" methods that you have will be appreciated. I always have trouble with brake systems for some reason.

Have you started with the wheel furtherest away from the m/c then worked your way back towards it?

i.e start with the rear wheel on the opposite side to the m/c and finish with the front wheel on the same side as the m/c.

Also make sure the nipple is fully closed before the pressure is taken off the brake peddle. It doesn't take much to such air back into the system.

You stated that you are going to blead the master again..............
Did the fluid resivuar ever go empty?
If your bleading the master eather with a kit, Or you have blead it already, The master needs to be level.
Eather by jacking up the rear of the vehical or done in a vise

The master never went empty. We have bled with the rear end raised up and with it level (jacked up evenly), and the wheels in every order possible. I'm not sure if the master was ever completely level during bleeding (it sits at a slight angle on the booster).

It won't let me edit for some reason.

I wanted to add that the fluid that was in the system to begin with looked to be the original fluid, if that matters at all.

Try this.
start the vehical, pump the peddel three four times, now hold it.
slowly start to let off the peddel. slowly. As your letting off you will still feel back pressure on the peddel pushing back at your foot. Now you lightly push back. feather the peddel with pressure and letting off just a little and re-applying pressure.
If the master is bad, the peddel will fall to the floor during this process.
Does the peddel go all the way to the floor?

Pretty close. When its running, the pedal will go about 2/3 of the way down, and then the rest of the travel is very springy. You can force it to the floor, but it gets pretty stiff after 2/3 travel.

if the master never went dry, then it has to be a problem with the rear brakes.

Could be defective calipers

How would I go about testing for a defective caliper? They both grab quite well (spinning the rotors by hand), and pump up within one pump after bleeding (pump, bleed, one dead pump, second pump will bite). Both sides act about the same, although the passenger side caliper looks like it moves around more when the pedal is applied.

I played with it a little more today. The rubber hoses do not swell up at all, the pedal will only pump up a little with the car off, none with the car running. If I press the pedal in quick sucession, it feels like I hit a wall after so much travel, but a slow pump will travel all the way to the floor. The master cylinder makes some noise, but there is no spray with the cap off.

With a 16 year old car and those symptoms, I'd get a master for it. When bleeding brakes, most people make the mistake of bottoming out the brake pedal. This pushes the master cylinder rubber cups past this ring of crud in the master bore and the cups wind up leaking.

Get a rebuilt or new master, bench bleed it, install it and bleed each caliper. I use this method of bench bleeding and it always works. I lock an ear of the master in a bench vise, fill it up with fluid and leave the cap off. I press two fingers over the brake line holes in the side and pump the master with a screwdriver. You'll see air bubbles come up through the fluid in the reservoirs, when the bubbles stop, the master is bled. Put the cap on and install it.

Also, as a wild thought, I've seen calipers installed on the WRONG sides of the car before. This puts the bleeder screw down instead of up.

Bob

With a 16 year old car and those symptoms, I'd get a master for it. When bleeding brakes, most people make the mistake of bottoming out the brake pedal. This pushes the master cylinder rubber cups past this ring of crud in the master bore and the cups wind up leaking.

Get a rebuilt or new master, bench bleed it, install it and bleed each caliper. I use this method of bench bleeding and it always works. I lock an ear of the master in a bench vise, fill it up with fluid and leave the cap off. I press two fingers over the brake line holes in the side and pump the master with a screwdriver. You'll see air bubbles come up through the fluid in the reservoirs, when the bubbles stop, the master is bled. Put the cap on and install it.

Also, as a wild thought, I've seen calipers installed on the WRONG sides of the car before. This puts the bleeder screw down instead of up.

Bob

I agree with bob replace master cylinder.... pedal to floor is master cylinder n/g.....why ? brake pedal pushed down too far damaging seals on master cylinder and don't forget bad,wrong or contaminated fluid... if pedal was spongy but did not go to floor I would say air.... this is bad master cylinder...

I agree with bob replace master cylinder.... pedal to floor is master cylinder n/g.....why ? brake pedal pushed down too far damaging seals on master cylinder and don't forget bad,wrong or contaminated fluid... if pedal was spongy but did not go to floor I would say air.... this is bad master cylinder...

This is a common mistake made by pros too. I did a lot of brake work in one shop and we had a circle of people in the shop that we'd use to bleed brakes. Most of our work was bled with a power bleeder but we did the front calipers and the problem jobs the old fashioned way.

The person at the pedal has to be told how hard and what speed to push the pedal. The person on the bleeder does this and has to know how far to crack open the bleeder. Most of the time I just help a finger over the bleeder and left it open until that corner of the car was bled.

When you do over a few hundred brake jobs a year, you pick up on what works and gets the cars out so they don't come back!

Bob

I went out this morning to try a gravity bleed, just for the hell of it. I put a clear hose on the right rear bleeder and opened it. A little fluid filled the first ince or two of hose (it was pointed up), and then nothing. I waited a few more seconds, and saw a few air bubbles escape. I tried lightly tapping on the caliper, but no more air came out. The fluid was coming out very slowly, and no air appeared to come out when I tried the other wheels. I still don't have much of a pedal, but it did feel a little bit stiffer.

I got my sister to pump the pedal for me, but I was unable to get any more results from a quick bleed of both rear wheels.

Gravity bleeding gets you only so far, not very. I've never tried it in all the years I've done brakes. Bleeding brakes with a bum master cylinder only gives the person pushing the pedal a little exercise.

You also have to have a dialog going with the pedal-pumper, a simple "down" and "up" works fine. Keep the car doors open so they can hear you under the fender. Use "stay down" when you are closing the bleeder screw. You have to be in synch with each other or MORE air can be added to the system.

Good luck!

Ok. I have one more trick left to try. On my '83 Toronado, I couldn't get the brakes bled for anything, and I replaced everything because I didn't know any better. I ended up using a syringe from work to pull fluid from the lines, rather than pumping. I don't know why it worked, but it did, so I'll try it. If that doesn't work, I'll put a master on it Saturday.

Ok. I have one more trick left to try. On my '83 Toronado, I couldn't get the brakes bled for anything, and I replaced everything because I didn't know any better. I ended up using a syringe from work to pull fluid from the lines, rather than pumping. I don't know why it worked, but it did, so I'll try it. If that doesn't work, I'll put a master on it Saturday.

In addition to what was said here about brake bleeding I would like to add this....when replacing pads or calipers I always open bleed valve and then push caliper pistons back fully, this then removes the caliper piston fluid from system and then does not return the heat damaged fluid to master cylinder...this has always worked for me as I keep my vehicles a very long time and i have never had to replace a master cylinder or brake caliper....my first vehicle was in 1967 I am working on vehicle #4 now.....

Well, I had to wait a week for the master to come in, but its been bench bled according to the Nissan FSM (hold your fingers over the ports and have someone else pump the pedal until no air comes out the reservoir) and installed. The car still has no pedal, so I'm assuming there's just more air trapped in there, although we're still getting nothing at the bleeders.

Is vacuum bleeding worth trying at this point?

Thanks for all the advice thus far.

Well, I had to wait a week for the master to come in, but its been bench bled according to the Nissan FSM (hold your fingers over the ports and have someone else pump the pedal until no air comes out the reservoir) and installed. The car still has no pedal, so I'm assuming there's just more air trapped in there, although we're still getting nothing at the bleeders.

Is vacuum bleeding worth trying at this point?

Thanks for all the advice thus far.

something is wrong here ......can you describe how you installed this master cylinder? like is the master cylinder connected to the brake pedal??

The FSM said to bolt the master to the brake booster, but not hook up any lines. It then said to plug the ports with my fingers while someone else pumped the pedal until air no longer came out (I went until the air bubbles coming out of the reservoir). We did have trouble with one line threading in, and I think it may be sucking in air. I'm going to disconnect it and see if anything is wrong.

If any air has been sucked in, is there any way to bleed the master without unhooking all the lines? Also, the kit that came with it did not work (the plugs didn't screw in and the hoses wouldn't fit on the plugs).

Well, we got the bleed kit that came with the master to work (after a few modifications) and bled until there was no air coming from the lines. We had a good pedal after just hooking it up, but went to each wheel a few more times to make sure - no air.

The pedal was nice and stiff until the engine was started, then it went straight to the floor again. After shutting it off, it feels like there is a little less pedal than before, but its still nice and stiff. I see no leaks, nor do I hear any hissing.

Well, we got the bleed kit that came with the master to work (after a few modifications) and bled until there was no air coming from the lines. We had a good pedal after just hooking it up, but went to each wheel a few more times to make sure - no air.

The pedal was nice and stiff until the engine was started, then it went straight to the floor again. After shutting it off, it feels like there is a little less pedal than before, but its still nice and stiff. I see no leaks, nor do I hear any hissing.

after bleeding it is not unusual for pedal to go to floor as the vacuum that was in booster needs to build up..... next check booster vacuum lines for any leaks....

After changing both rear calipers, pads, and rotors, I cannot get the pedal on my sister's Maxima to stay up. I can bleed everything, get a good pedal, let it sit, and then the pedal is low again. I've been told to change the master cylinder, but I'd like a second opinion since its not my money.

The car is a '92 Maxima SE with 4 wheel disk brakes and no ABS. The fluid is new in the entire system, and it has been through about 3 quarts of fluid since I started bleeding. The pedal is high but spongey with the car off. With the car running, the pedal is about 2/3 of the way to the floor and still spongey. It will sink after only a few minutes of sitting.
Hey there. I am hoping I might be able to give you a slighty more indepth reply to your question. After reading the replies between you and the others, I think I have enough information. lol. As far as the master cylinder goes, it very well could be that. The most obvious symptom of a blown master cylinder, is that the pedal goes all the way down. Now, I'm and not saying it goes most of the way down, it goes ALL the way down, till its just about touching the floor of the car. Your car will most likely still have drum brakes in the rear. Have you noticed any fluid leaking out of it? Either when the car has sat a while, or when it has been running? A blown master cylinder usually just lets in air, and you a losing fluid. That fluid is going somewhere. Can you find it? Even for as much as you are losing, it could only be a small leak, so you might have to watch for it. Park the car on dry concrete, try letting it sit without running for a couple hours, than try letting it sit for a while when its running, preferrably warmed up.

Now, if I am right about the car having rear drum brakes, it sounds to me like you have a bad Wheel Cylinder. And you might have to go as far as pulling the drum brakes off to fully see the leak.

If you do not have rear drum brakes, than in that case I would agree with others suggestions of a master cylinder.

Another thing that would be wise to look for, is a brake in any of the lines. You have brake lines that start at the master cylinder, and follow down under the car to each of the brakes on your car. Get out a flash light and follow the brake lines as best you can. You might need to jack up the car to get a true look at them. But look them over thoroughly.

It is wise to seek a second opinion on any pricey car repairs. A lot of mechanics will give you a "quick" quote to sell you on the repair. If they did not look at it for at least an hour, then they did not look thoroughly enough.

You can easily get an idea of the correct diagnosis for your car by going through a process of elimination (POE), which is what most experienced mechanics go through, and it usually doesnt include a computer or any tools to do that.

If your looking for anymore information, this web site is an awesome help
http://www.troubleshooters.com/tautomot.htm
and so it this one
http://www1.autozone.com/UseCase,S001/UserAction,viewSimpleDiagInfo/Parameters,info/getInTheZone.htm

They both have great easy trouble shooting guides.

If you'd like anymore information from me, check out my page at
http://www.myspace.com/acceleratedautomotive

Good Luck!

This is wrong, and I'm a bad person. However, I am going to he'll anyway so....:evillol: ....


If you'd like anymore information from me

NO!

know this is an old(er) thread, but what did you come up with? I just found/joined this forum.
Question, was the pedal OK before you replaced the rear parts?
I wanted to comment that on these type calipers, where the e-brake acts on the piston, and when replacing the rear pads, that require you to wind in the piston, sometimes the piston needs to be wound out to where there is minimal clearance between the piston and the pad/rotor.
Sometimes the piston is wound too far in, and this will give you your low pedal.

Another thing I have ran into, and you would not think it was an issue, but are the front caliper sliders nice and free?
Sometimes this can give you a low/spongy pedal.
Tony

Gravity bleeding gets you only so far, not very. I've never tried it in all the years I've done brakes. Good luck!

YMMV, but having to work alone at home a lot of times, I have got a 100% full brake pedal from gravity bleeding.
A few times have then found a "helper" but have not gotten any more air from the system.
Tony

Sorry, I never posted when I found out what the problem was. The drivers side rear caliper was defective. It started visibly leaking after a while.

Sorry, I never posted when I found out what the problem was. The drivers side rear caliper was defective. It started visibly leaking after a while.


thanks for that info..... now that makes sense,, soft,, falling pedal was a leak.... what is strange is the new caliper was defective.......where did you buy it,,, and who was the manufacturer......??????

Mrbreezeet1, thanks for your useful info!

I seem to have a thing for defective rear calipers. I went through more than one on my '83 Toronado a few years ago.

This set came from Advance Auto Parts. I think the (re)manufacturer was Cardone.

I seem to have a thing for defective rear calipers. I went through more than one on my '83 Toronado a few years ago.

This set came from Advance Auto Parts. I think the (re)manufacturer was Cardone.


thanks as i use that auto parts store at times...i got a thermostat for my 5.3 sil there and its slow to get temp to normal after 4months of use ,,, lifetime warrantee,, but the original is still better then this new one....i'll be replacing it shortly..

we have a saying at the shop. Its "you've been cardoned!"

Kind of like saying, "you've been scammed!"

cardone = crap

we have a saying at the shop. Its "you've been cardoned!"

Kind of like saying, "you've been scammed!"

cardone = crap

That's not cool. I thought that cardone was a good brand, since it was the first of about 10 that held up on the Toronado.

Any suggested brands? I'm sick of spending weeks in the garage and looking like I don't know what I'm doing beacause of faulty parts.

I'll be installing the replacement caliper on the Maxima tomorrow. I'll let you know how it goes.

Any suggested brands?

as far as remans? Not really.

Not very helpful, but stay away from anything that comes in a white box.....or anything from Centric

And anything reman'd in general.

Like I said, not very helpful.

I should add, reman calipers aren't usually a sore spot (far from unheard of, but not like many other areas....such as anything dealing with electronics)

Some categories, all you can get for reasonable prices are remans. This is one of them. I deal mostly with carquest reman calipers, and we have a pretty good success rate with them. But I'm not sure who they go through....as with most part stores, they are just relabeling it.

But I have delt with a lot of centric and cardone calipers. I'd say its 1 in 20 sets that I have problems with. Thats very good compared to other components

some manufacturers do offer remans, I should point out. I'd trust them a lot more than "white box" remans, such as cardone. Might be worth checking on.

I'll be installing the replacement caliper on the Maxima tomorrow. I'll let you know how it goes.

Yea let us know how it works out.
I've got a few bad wheel bearings(front) from advance, one had a 1/4" of play in it. Or ABS sensors that went open,turning on the ABS and traction lights.
Customer took it to the dealer and told them open sensor XX front bearing, and I checked it with an ohm meter, (No Reading)
So when I had that problem on other car's, I checked both bearing sensors and found one open, and was able to fix the traction control/ABS light problem. These were GM cars.
Usually had pretty good luck with there calapiars,(Advance)not sure what the brand was.
Auto zone and advance were always pretty good about there warranty's though.
Auto zone just ordered me a new $80.00 flex pipe for my excort under warranty,still had in in there computer from 5 years ago from another state, using my old phone #.Didn't even neet the recipet.
Tony

Well. The new caliper didn't help much. The pedal came up higher than its ever been, but still falls to the floor with the engine running. It doesn't pump up much, but once you stop pumping, it sinks right to the floor. I see no air coming from the bleeders.

The new caliper didn't help much. The pedal is much higher than its ever been, but it still bottoms out once the engine is started. If you pump the pedal, it will slowly come up, but sink as soon as you stop. Once the engine is stopped and the booster depleted, the pedal will return to its nice, high spot. It doesn't sink if you hold the pedal with the engine off.

Woo. Finally made some progress. The brake lines for the rear were leaking, but the fluid was pooling in a mud guard and we didn't see it. Hopefully we can get this car back on the road tomorrow.

Woo. Finally made some progress. The brake lines for the rear were leaking, but the fluid was pooling in a mud guard and we didn't see it. Hopefully we can get this car back on the road tomorrow.

this is what i would expect to find, leaks causing brake pedal to drop....


you now must inspect all brake lines and replace any that are rusted as when you need a full brake the lines may blow out...


whenever fluid levels drop you have a leak.... brake fluid should very slowly drop as the pads/shoes wear...if it is required to add fluid beyond this you have a leak...