1998 Blazer 4x4 Rear Brakes Not Working
#1
05-17-2010, 01:27 AM
1998 Blazer 4x4 Rear Brakes Not Working
Hey guys, I'm new here to the forum. When doing some repairs recently I found this place when googling how to replace a wheel bearing assembly, and I've been hooked!
Anyway, about the car: It is a 1998 Blazer 4x4 I got it from my parents and it's an overall great running vehicle. Only snag is that when I recently had my oil changed and tires rotated, I was told and shown that the rear brakes are not working. The pads and rotors are fine, I'm told, but it does not seem that the pads are pushing against the rotor to stop the car.
The mechanic told me it could be one of a few things: the brake lines may be rusted out, there could be a problem with the master cylinder (or something worse, perhaps?). Now, when they looked, there was no brake fluid in my reservoir and so they topped it off, but it's been a few days and the brake light still hasn't kicked off.
My question, what course of action should I take to determine the problem myself? I was thinking of bleeding the brakes all around this weekend, figuring that if i bleed the back brakes and nothing comes out, then that means the brake lines are rusted out, or is that a misconception? Not sure, as this is all new to me...
In any case, any help on this matter would be appreciated, as I am slowly fixing this car up so that I can drive around in style
- Adrian
Anyway, about the car: It is a 1998 Blazer 4x4 I got it from my parents and it's an overall great running vehicle. Only snag is that when I recently had my oil changed and tires rotated, I was told and shown that the rear brakes are not working. The pads and rotors are fine, I'm told, but it does not seem that the pads are pushing against the rotor to stop the car.
The mechanic told me it could be one of a few things: the brake lines may be rusted out, there could be a problem with the master cylinder (or something worse, perhaps?). Now, when they looked, there was no brake fluid in my reservoir and so they topped it off, but it's been a few days and the brake light still hasn't kicked off.
My question, what course of action should I take to determine the problem myself? I was thinking of bleeding the brakes all around this weekend, figuring that if i bleed the back brakes and nothing comes out, then that means the brake lines are rusted out, or is that a misconception? Not sure, as this is all new to me...
In any case, any help on this matter would be appreciated, as I am slowly fixing this car up so that I can drive around in style
- Adrian
#2
05-17-2010, 02:20 AM
I doubt the brake lines are rusted out. You could have siezed calipers, you can check them by pressing them back in with something when you have the wheels off. Careful not to knick the black rubber part on the piston. They should go back into the caliper easily, if they dont move, or are very hard the the caliper is done.
You also have a Metering valve, and a Proportioning valve. The metering valve triggers you rear brakes a microsecond before the fronts to stabilize the rear of the vehicle, this might only happen on hard hard braking I cannot remember from trade school. The proportioning valve splits the fluid pressure so that there is more pressure going to the front brakes for more front braking force. If either of those valves have a plug in them then your rears could not get the pressure to them.
You can take the cap off your brake fluid resevoir and look in there as someone else VERY LIGHTLY presses the brake pedal, and then VERY LIGHTLY lifts up off it. You should see fluid returning to both of the cells in the master cylinder. If you dont see the fluid returning, then you could have a bad master cylinder. If you press hard and fast with the cap off you will have fluid allover the place, so do it really slow.
You might want to adress where your brake fluid is going first. It shouldnt just dissapear. If you cant find a leak at the wheels then try seeing if there is oily mess on the bottom front of your brake booster, its what the master attaches to. The master can leak from the input seal and its tricky to see down there. Also inspect the brake lines themselves all the way back to the master, you will find the 2 valves I mentioned too. They look like little tetris peices with the lines going into them. They may also have bleeder screws on them so you can open them and see if fluid is getting to them.
How did an oil change guy determine your rear brakes are not working, are your rear rotors rusty
You also have a Metering valve, and a Proportioning valve. The metering valve triggers you rear brakes a microsecond before the fronts to stabilize the rear of the vehicle, this might only happen on hard hard braking I cannot remember from trade school. The proportioning valve splits the fluid pressure so that there is more pressure going to the front brakes for more front braking force. If either of those valves have a plug in them then your rears could not get the pressure to them.
You can take the cap off your brake fluid resevoir and look in there as someone else VERY LIGHTLY presses the brake pedal, and then VERY LIGHTLY lifts up off it. You should see fluid returning to both of the cells in the master cylinder. If you dont see the fluid returning, then you could have a bad master cylinder. If you press hard and fast with the cap off you will have fluid allover the place, so do it really slow.
You might want to adress where your brake fluid is going first. It shouldnt just dissapear. If you cant find a leak at the wheels then try seeing if there is oily mess on the bottom front of your brake booster, its what the master attaches to. The master can leak from the input seal and its tricky to see down there. Also inspect the brake lines themselves all the way back to the master, you will find the 2 valves I mentioned too. They look like little tetris peices with the lines going into them. They may also have bleeder screws on them so you can open them and see if fluid is getting to them.
How did an oil change guy determine your rear brakes are not working, are your rear rotors rusty
#4
05-17-2010, 05:00 PM
I doubt the brake lines are rusted out. You could have siezed calipers, you can check them by pressing them back in with something when you have the wheels off. Careful not to knick the black rubber part on the piston. They should go back into the caliper easily, if they dont move, or are very hard the the caliper is done.
You also have a Metering valve, and a Proportioning valve. The metering valve triggers you rear brakes a microsecond before the fronts to stabilize the rear of the vehicle, this might only happen on hard hard braking I cannot remember from trade school. The proportioning valve splits the fluid pressure so that there is more pressure going to the front brakes for more front braking force. If either of those valves have a plug in them then your rears could not get the pressure to them.
You can take the cap off your brake fluid resevoir and look in there as someone else VERY LIGHTLY presses the brake pedal, and then VERY LIGHTLY lifts up off it. You should see fluid returning to both of the cells in the master cylinder. If you dont see the fluid returning, then you could have a bad master cylinder. If you press hard and fast with the cap off you will have fluid allover the place, so do it really slow.
You might want to adress where your brake fluid is going first. It shouldnt just dissapear. If you cant find a leak at the wheels then try seeing if there is oily mess on the bottom front of your brake booster, its what the master attaches to. The master can leak from the input seal and its tricky to see down there. Also inspect the brake lines themselves all the way back to the master, you will find the 2 valves I mentioned too. They look like little tetris peices with the lines going into them. They may also have bleeder screws on them so you can open them and see if fluid is getting to them.
How did an oil change guy determine your rear brakes are not working, are your rear rotors rusty
You also have a Metering valve, and a Proportioning valve. The metering valve triggers you rear brakes a microsecond before the fronts to stabilize the rear of the vehicle, this might only happen on hard hard braking I cannot remember from trade school. The proportioning valve splits the fluid pressure so that there is more pressure going to the front brakes for more front braking force. If either of those valves have a plug in them then your rears could not get the pressure to them.
You can take the cap off your brake fluid resevoir and look in there as someone else VERY LIGHTLY presses the brake pedal, and then VERY LIGHTLY lifts up off it. You should see fluid returning to both of the cells in the master cylinder. If you dont see the fluid returning, then you could have a bad master cylinder. If you press hard and fast with the cap off you will have fluid allover the place, so do it really slow.
You might want to adress where your brake fluid is going first. It shouldnt just dissapear. If you cant find a leak at the wheels then try seeing if there is oily mess on the bottom front of your brake booster, its what the master attaches to. The master can leak from the input seal and its tricky to see down there. Also inspect the brake lines themselves all the way back to the master, you will find the 2 valves I mentioned too. They look like little tetris peices with the lines going into them. They may also have bleeder screws on them so you can open them and see if fluid is getting to them.
How did an oil change guy determine your rear brakes are not working, are your rear rotors rusty
Yeah, the rear rotors are rusty, and that was one thing, about the calipers that is... he mentioned that the calipers could just be seized... idk... I just didn't want to pay whatever they were going to charge me just to look at it and find out its something easy, or find out it's something ridiculously complicated...
Again, thanks for the help!
nah, no one's done rear brake work on it as long as I have owned it (past 2 years)
#5
05-23-2010, 10:05 PM
Just an update on this: I had it looked at by my regular mechanic and he confirmed (most of) my suspicions. Instead of the hose, tho, it was a leak on the caliper itself. Ended up replacing it completely and altogether ran about 80 bucks with labor.
since the rotors are a bit rusty, they squeak a bit, but nothing a cleanup can't fix!
since the rotors are a bit rusty, they squeak a bit, but nothing a cleanup can't fix!
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