Need some help..BRAKE ISSUE...New Rotors/Pads/Calipers/Fluid etc
 

Hello guys,

I have a serious issue here with my daughter's 96 Blazer (4.3L Auto 4x2).

When we bought the Blazer we noticed that the brake pedal was a bit soft and it didnt stop on a dime (even though I wouldnt expect it to).

I decided before I give my daughter the keys, I would run through and do all the basic maint. stuff to it.

Well today I did the front brakes to include rotors, pads, calipers, speed bleeders and fluid.

This is where it gets scarey.....if I am going down the road, lets say under 40 MPH and get on the brakes, the engauge nicely and the Blazer comes to a stop...not on a dime, but she does stop. Pedal is a bit soft still, but I can live with that. However, if I am over 40 MPH or so and hit the brakes, the pedal is locked up and wont go down a 1/2".....if I stay on the pedal, it will pulsate, finally start to head to the floor, but jerks the Blazer to the left severley....I mean like BAM..Im in the left lane now and boy what body roll!

I limped it back home, scared crapless and checked for leaks. Didnt find any...so I re-bled the front calipers (didnt touch rear drums..dont know much about them). Didnt see any air bubbles...just nice clean, clear brake fluid. Took her out for another road test and same symptoms persist.....under 40 or so, Im golden....if Im over 40 MPH, watch out cause she wants to jump in the other lane....

On this last trip out, I heard some grinding from the front passangers side, but when I was under there earlier, all looked well and in place....

You guys got any insight for me....I dont want to turn the Blazer over to my daughter in such condiditon.............

couple of things i would look at.

are the pads moving freely on the caliper guides? i know i have had to file some pads to make sure they wouldnt bind up. i just file a small amount on the steel part that sits on the caliper mount. also make sure all parts can move freely.

if she is pulling left then you have an issue on the right side. the left is locking up and the right is not, causing the blazer to rotate in the direction of the side with momentum.

are the wheels hot? not the rotors but the wheels themselves...that is a sign that the pad is binding and heating up the rotors..then wheels. sometimes you can see the rotor become discolored.

Hello and thanks for the reply...My computer is giving me issues with the search function at this time, so I am limited on what I can research at the moment.

I will put my responses in red....


Yes they both are...I touched them about 10 mins after shutting her down and they were both very warm to the touch. I figured it was because they were brand spanking new and maybe needed to wear just a bit. I only drove it like 10 miles after install.


On a side note, is there anything special in bleeding brakes for the 96 Blazer? I had a 94 GMC Sierra for years and did brakes a few times..just run of the mill bleeding...pump, pump, pump, helper holds pedal...I release bleeder...repeat until no air bubbles were present and clear fluid was visable...

When bleeding brakes, you want to start with the one furthest from the fluid reservoir. Start at the right rear, then left rear, right front, and finish on the left front. If you felt you needed to replace the front brakes, I'll guarantee that the rear shoes are worn as well. In my experiences, they're done long before the front pads. Easy peasy to do, just take a photo of how the springs are installed before you take them apart. New spring kits are really inexpensive and recommended. If and when you do them, check that the drum's inside surface is smooth. If not, replace them, too. They are also not too expensive. All I've ever needed for tools to do them are channel-lock pliers, needle-nose pliers, and a flathead screwdriver. They bleed exactly the same as disc brakes. The bleeder valve is on the back side at the top. Good luck!

If you did the "pump, pump, pump" as part of the "repeat", you may have still have air in the system. The master cylinder needs about 15 seconds after your assistant releases the brake for the pistons to reset completely. As stated above I would do a complete bleed with all 4 wheels to insure you have no air in the system (I wouldn't do the "pump, pump, pump" anymore). You may also want to do gravity bleed.

Hello and thanks for the reply...I plan on doing the rear drums in a short while with the help of a mechanic friend...I dont know jack about them...watched some Youtube.com videos from A1Auto and it does look pretty straight forward.

Well here is an update.....

I was able to use the search function and read a post or two about the ABS module may being the culprit. I havent had any lights come on the dash, but for craps and gigs, I went and pulled the 10A fuse from drivers side dash area.

Went out for a cruise and the hard pedal / locking up issues are now gone....I now have some really cool looking ABS lights (orange) and BRAKE light (red) on the instrument cluster.

Could this maybe give me a clue and safe to say the ABS module thingy is FUBAR'd?

Thanks again....

******on a side note*****...going to reinstall fuse and go for another drive. Honey-do list is kicking my ass, so didnt get a chance to pull wheel for another visual inspection.

In your experience the rear shoes are done before the front pads? Either I am getting ****ty front pads, or the rear ones are made out of diamond dust. Same with my 94 when I had it.

Sounds like that big ol abs block is the issue. Which is somewhat common with these. Tehy are extremely expensive to replace with new,and you are gambling with one from a salvage yard. Id check out the wheel sensors and see if any wires are broken. Is your check engine light working? (turn key to on position and see if she lights up)Rears arent used much,except for heavy braking and ebrake.

Hello agian,

Put the fuse back in and BAM...braking issue is back....so its in the ABS for sure I would say. Ill just keep the fuse pulled for the time being.

I will replace the ABS sensors, one at a time, reinstall fuse and test drive to see if maybe a certain sensor is being the culprit (will help futute searchers of this type of braking thread).

Anywho, dont think replacing sensors is hard....

Ill post a pic of my ABS unit to see if you guys think its a commom unit or off the wall one. I read some posts on Module Repair, but am getting the feeling they only repair certain ones.

Both ABS and Engine light work....ironically the engine light is staying on after I put the ABS fuse back in...

Time to buy a code puller....

As well as a code reader, you may want to buy the subscription for your specific vehicle on alldatadiy.com. It's an electronic version of the dealer shop Technical Service Manual. There are troubleshooting steps and diagnostics for the ABS system that you might want to try instead of replacing parts one-by-one.