Brake Help

I have a problem with my brakes that accured today I have no pressure in my brakes I hit the floor with the pedal and nothing happens if I have the car off there is pressure in the pedal I checked the brake fluid and it seems to have fluid only in the back of the master cylinder but is up to the max line. does anyone have any ideas of what I can do to get this working again by the way its 0 degrees out here.

add more fluid to front and have someone pump brakes wile u bleed the lines and look for leaks:wink:

also could be problem with abs if you have it, i no the pedal drops to the floor and brakes practicly dont do anything if abs is engaged eg. skidding tires (happened to me at an intercection, thought i could beat the light and i was wrong:licka:)

What year and model S/T do you have? 2 or 4 wheel drive? Disc or drum rear brakes? How many miles on the vehicle? What is the repair history with the brakes? Is the vehicle equipped with ABS? The more information you give us, the easier it will be to help diagnose the problem.

I have a 1998 GMC Jimmy SLE 4x4 with 215,000 miles on her Im trading it in on a new vehicle on wed and need to get this problem repaired I took it to a shop to have it looked at. they told me it was the master cylinder so I ordered a new master cylinder cause they were charging me $200 and I can get it for $90 total they were going to charge me $340 to install im going to take the challange on to do it myself is there a site or anything that will help me tackle this job? thanks I appreciate the help. (it does have ABS)

I need to replace master cylinder on a 1998 GMC Jimmy SLE 4x4 with ABS I know you guys have done this and I need to know how to! or what to watch out for. is this job pretty simple. Im not sure on the bleeding part the last time I did it was on a ATV. thanks for the info.

First thing to do is bench bleed the master, after installing you may have to bleed the abs unit this can be tricky at times without the Tech 11 GM scannner.

Lets diagnose this thing correctly before you replace the master cylinder and then find out it's something else.

Fluid in one half of the master cylinder reservoir, and the pedal going to the floor, both indicate there is a leak somewhere. Is the red brake warning light on the dash illuminated with the vehicle running? Or does it come on when the pedal goes to the floor? Is the ABS light on?

Threads merged. Please don't clutter the forums with multiple threads for the same problem.

Can anyone provide me with some insight, I'm having nearly the same problem.


Info:

98 GMC Jimmy 4.3l vortec 4x4 4wheel disc


Problem:

Hit the brakes to swerve around a moose, heard a "pop" sound, the brakes felt funny, pumped them and they came back but felt very soft and the braking was not responsive at all.

Noticed:

Checked under the hood, front half of the master was dead empty, back half (closest to cab) was full. No leaks seen anywhere, no brake light came on (ABS light already on as I pulled it's fuse because it would randomly go off). I added fluid to the master in hopes that I could pump the brakes and find the leak but no fluid came out anywhere (wtf??) no matter how much we pumped or held the pedal. A day later the brakes are still very underpowered (assuming I'm running on only 2 wheels if half my system is compromised, so I parked it until it's to be fixed) but the master hasn't lost any fluid.



So the fluid had to go somewhere, is there a valve that stops leaks when a sudden drop is detected? I mean I -had- to have blown a line or hose or fitting or something somewhere in order for the pop and half a master of fluid to disapear. But also there is no fluid disapearing now, how is that possible?? Anyone?

Can anyone provide me with some insight, I'm having nearly the same problem.


Info:

98 GMC Jimmy 4.3l vortec 4x4 4wheel disc


Problem:

Hit the brakes to swerve around a moose, heard a "pop" sound, the brakes felt funny, pumped them and they came back but felt very soft and the braking was not responsive at all.

Noticed:

Checked under the hood, front half of the master was dead empty, back half (closest to cab) was full. No leaks seen anywhere, no brake light came on (ABS light already on as I pulled it's fuse because it would randomly go off). I added fluid to the master in hopes that I could pump the brakes and find the leak but no fluid came out anywhere (wtf??) no matter how much we pumped or held the pedal. A day later the brakes are still very underpowered (assuming I'm running on only 2 wheels if half my system is compromised, so I parked it until it's to be fixed) but the master hasn't lost any fluid.



So the fluid had to go somewhere, is there a valve that stops leaks when a sudden drop is detected? I mean I -had- to have blown a line or hose or fitting or something somewhere in order for the pop and half a master of fluid to disapear. But also there is no fluid disapearing now, how is that possible?? Anyone?

try jacking up one side of the truck, and have some one hold down the brakes wile you try to sping the tires, if eighther the back or front move then thats where you start..first see if the line is getting pressure when your on the brakes, if it is then there is most likely somthing wrong in the caliper's and start taking that apart to see.

if all that is fine try checking where the brake pedal runs to the cylander or whater it does (havent messed with that part of brake system on jimmy's or blazer's) you might have extended a spring or cable or somthing (took a shot in the dark saying that)

try jacking up one side of the truck, and have some one hold down the brakes wile you try to sping the tires, if eighther the back or front move then thats where you start..first see if the line is getting pressure when your on the brakes, if it is then there is most likely somthing wrong in the caliper's and start taking that apart to see.

if all that is fine try checking where the brake pedal runs to the cylander or whater it does (havent messed with that part of brake system on jimmy's or blazer's) you might have extended a spring or cable or somthing (took a shot in the dark saying that)

I have 4 wheel disc so I don't have any springs to worry about. I think I'll just bring it to a shop, I -hate- doing that but I split my leg open with a chainsaw while at work yesterday so now I can't even do any work on it without risking ripping all these stitches out. Maybe I'll try jacking it up though just to see what tires are affected and save some diagnosing cash.

Does anyone know if the front and rear calipers are seperate systems or does the jimmy brake system seperate a front right and rear left from the front left and rear right tires? (X pattern system so if you blow a line you still have one front and one rear on opposite sides braking).

This thread is already old and merged.
Always check the date on a thread and if it is old just let sleeping dogs sleep.
They tend to bite if woke up when sleeping.
If you have a problem on your car or truck start a new thread and someone will help you.

This thread is already old and merged.
Always check the date on a thread and if it is old just let sleeping dogs sleep.
They tend to bite if woke up when sleeping.
If you have a problem on your car or truck start a new thread and someone will help you.

Here's the deal. Every forum out there complains when someone starts ANOTHER thread with the SAME problems that have been discussed. I had the SAME problem and didn't want to get in trouble for starting a dupe thread. I had different questions and different diagnosis info to add to this thread so I added my replies. It doesn't hurt anything and in fact makes life easier for someone who searches for this problem because now instead of reading 5 threads to find 5 different puzzle peices he can read just this one and see multiple angles. Thanks for your useless post though.


From the mod himself

Threads merged. Please don't clutter the forums with multiple threads for the same problem.


Thanks <rolling eyes>

Thread closed. MT is correct, bumping old threads is not allowed. Likewise, posting your problem is someone else's thread is also not permitted. The post of mine that you're referring to was targeted towards the threadstarter that posted this same thread in multiple forums. This forum sees a lot of visitors, most of whom need some type of help from a technical standpoint, these rules were created to make sure that they receive that help as quickly and efficiently as possible.

I'll give you a quick explanation of why these rules are necessary.

Old threads - This is from the Community Participation Guidelines (http://www.automotiveforums.com/vbulletin/guidelines.html) "Please avoid posting or voting in outdated threads. It merely clutters up the message board and makes it more difficult for fellow members to sort through the vast amount of information contained on the boards. If you have new and important information to add regarding a past discussion, feel free to start a new thread and if need be, add a link to the original thread."

Starting a new thread and not posting your problem in someone else's thread - Posting problems in someone else's thread causes confusion, it becomes difficult to keep things separate, and know which questions are being asked of which individual. Nearly 90% of the time, the problems turn out to be different, with similar symptoms, and require different means of diagnosis and repair, causing further complications and confusion.

For more information on the proper posting procedure please be sure to read the sticky that is posted in the main model forums of all the S-series vehicles. It is titled "Forum Rules! READ ME BEFORE POSTING! (http://www.automotiveforums.com/vbulletin/showthread.php?t=461174)"