98 Blazer brake issue while bleeding

[spartfaithful]

I recently had a driver side rear caliper that was stuck. I changed the caliper and proceeded to bleed the brakes manually. I initially only bled the caliper that I changed and there was a significant lack of pressure. I then proceeded to bleed all the brakes. So I started with the rear passenger and that one bled fine. When I did the next caliper (rear driver) all of a sudden no brake fluid was coming out of the bleeder screw.

Why would this happen?

Now I have almost no prake pedal pressure.

Please help

[MT-2500]

Originally Posted by spartfaithful

I recently had a driver side rear caliper that was stuck. I changed the caliper and proceeded to bleed the brakes manually. I initially only bled the caliper that I changed and there was a significant lack of pressure. I then proceeded to bleed all the brakes. So I started with the rear passenger and that one bled fine. When I did the next caliper (rear driver) all of a sudden no brake fluid was coming out of the bleeder screw.

Why would this happen?

Now I have almost no prake pedal pressure.

Please help

You tripped the equilizer valve over center. The block where the front and rear lines run threw under master cylinder. There is a plunger in it under the rubber boot if out you can push it in but if pushed in.
Go to the other end and open bleeder and see if it trips back.
They nake a holding too to hold it centered while bleeding.

If you have ABS brakes they may require a tech 2 scanner to bleed the ABS system.
MT

[muddog321]

98up all have ABS and the brake line "Ts" in the rear so you probably have air in the rear lines. Hope you changed the pass side caliper too cause the bleeder screw may be clogged or the caliper full of crap - common on those due to the plastic piston and lightweight design that gets pretty hot back there. If you don't have the money, then pull the bleeder screw out and make sure it is not clogged or replace it and bleed again both sides - should work and on Blazers you have to start it after bleeding to get the booster (power brakes) and ABS unit to pump up and then pedal pressure should be OK.

[Blazer SS]

One more thing to check. Use something to remove the brake fluid from your master cyl resevoir. pull out the two roll pins with a set of needle nose plyers. remove the resevoir. look at the two holes. there are two very small holes where the resevoir sat. the one for the rear brakes is probably clogged. If it is you will see the problem , just clean it out.

[spartfaithful]

I only changed the rear driver side caliper. When I started the bleeding process, I only did the caliper that I changed originally (rear driver). Then I drove it around the block and noticed very poor brake pedal resistance.

I then blead the rear passenger fine, then proceeded to the rear driver. The rear driver would not bleed. When the pedal was being pumped very little to no fluid was coming out of the bleeder screw. So I tried to start over to see if that would resolve the issue, and tried to bleed the rear passenger again. But this time even the rear passenger would not bleed. Little to no fluid coming out of the bleeder screw when the pedal was being pumped.

Now I am really confused????

[muddog321]

Open that bleeder up all the way and see if fluid comes out - maybe the bleeder is clogged - you can remove the bleeder screw and see if if fluid flows.

[Blazer SS]

Please check your resevoir.

[spartfaithful]

The resovior is full. I have been monitoring that closely. Also the amount of brake fluid that came from the bleeding does not equal the amount that I have refilled in the resovior.

[MT-2500]

Originally Posted by spartfaithful

The resovior is full. I have been monitoring that closely. Also the amount of brake fluid that came from the bleeding does not equal the amount that I have refilled in the resovior.

4WAL brakes or 2 wheel anti lock brakes?

4WAL brakes requires the use of a tech 2 scan tool to properly bleed them.
MT

[Blazer SS]

That is not what I meant by check your resevoir, I meant check your resevoir for dirt in the bottom.

To do this drain it and just look at the bottom, if you see stuff in it , remove the resevoir and clean it out!

There are two very small holes, almost pin size that the fluid has to pass through before it gets to the two chambers of the master cylinder.

when you bleed your brakes you draw a lot of fluid at once every time the pedal is lifted , if these very small holes are obstructed no new fluid can enter the master cylinder, so no fluid can enter the bake lines.

A tukey baster or a vacumn pump works nice.

[firepaw]

Originally Posted by spartfaithful

I only changed the rear driver side caliper. When I started the bleeding process, I only did the caliper that I changed originally (rear driver). Then I drove it around the block and noticed very poor brake pedal resistance.

I then blead the rear passenger fine, then proceeded to the rear driver. The rear driver would not bleed. When the pedal was being pumped very little to no fluid was coming out of the bleeder screw. So I tried to start over to see if that would resolve the issue, and tried to bleed the rear passenger again. But this time even the rear passenger would not bleed. Little to no fluid coming out of the bleeder screw when the pedal was being pumped.

Now I am really confused????

I'm confused, too! Are you "pumping" the pedal with the bleeder open?

[spartfaithful]

Thanks for all the replies. Here are the answers:

4 wheel disc brakes
I will check the resovior for dirt
I am pumping the brakes with the bleeder valve open

What is a tech 2 scan tool used for bleeding?

[blazee]

Originally Posted by spartfaithful

Thanks for all the replies. Here are the answers:

4 wheel disc brakes
I will check the resovior for dirt
I am pumping the brakes with the bleeder valve open

What is a tech 2 scan tool used for bleeding?

Looks like that's the problem. Bleeding brakes is a two person job. One person pumps the brakes and holds the pedal while the other person opens the bleeder. The bleeder must then be closed before releasing the pedal or it will suck air back into the system.

1. Begin at the corner furthest from the driver and proceed in order toward the driver. (Right rear, left rear, right front, left front.) While the actual sequence is not critical to the bleed performance it is easy to remember the sequence as the farthest to the closest. This will also allow the system to be bled in such a way as to minimize the amount of potential cross-contamination between the new and old fluid.

2. Locate the bleeder screw at the rear of the caliper body (or drum brake wheel cylinder.) Remove the rubber cap from the bleeder screw – and don’t lose it!

3. Place the box-end wrench over the bleeder screw. An offset wrench works best – since it allows the most room for movement.

4. Place one end of the clear plastic hose over the nipple of the bleeder screw.

5. Place the other end of the hose into the disposable bottle.

6. Place the bottle for waste fluid on top of the caliper body or drum assembly. Hold the bottle with one hand and grasp the wrench with the other hand.

7. Instruct the assistant to "apply." The assistant should pump the brake pedal three times, hold the pedal down firmly, and respond with "applied." Instruct the assistant not to release the brakes until told to do so.

8. Loosen the bleeder screw with a brief ¼ turn to release fluid into the waste line. The screw only needs to be open for one second or less. (The brake pedal will "fall" to the floor as the bleeder screw is opened. Instruct the assistant in advance not to release the brakes until instructed to do so.)

9. Close the bleeder screw by tightening it gently. Note that one does not need to pull on the wrench with ridiculous force. Usually just a quick tug will do.

10. Instruct the assistant to "release" the brakes. Note: do NOT release the brake pedal while the bleeder screw is open, as this will suck air back into the system!

11. The assistant should respond with "released."

12. Inspect the fluid within the waste line for air bubbles.

13. Continue the bleeding process (steps 11 through 16) until air bubbles are no longer present. Be sure to check the brake fluid level in the reservoir after bleeding each wheel! Add fluid as necessary to keep the level at the MAX marking. (Typically, one repeats this process 5-10 times per wheel when doing a ‘standard’ bleed.)

14. Move systematically toward the driver – right rear, left rear, right front, left front - repeating the bleeding process at each corner. Be sure to keep a watchful eye on the brake fluid reservior! Keep it full!

15. When all four corners have been bled, spray the bleeder screw (and any other parts that were moistened with spilled or dripped brake fluid) with brake cleaner and wipe dry with a clean rag. (Leaving the area clean and dry will make it easier to spot leaks through visual inspection later!) Try to avoid spraying the brake cleaner DIRECTLY on any parts made of rubber or plastic, as the cleaner can make these parts brittle after repeated exposure.

16. Test the brake pedal for a firm feel. (Bleeding the brakes will not necessarily cure a "soft" or "mushy" pedal – since pad taper and compliance elsewhere within the system can contribute to a soft pedal. But the pedal should not be any worse than it was prior to the bleeding procedure!)

17. Be sure to inspect the bleeder screws and other fittings for signs of leakage. Correct as necessary.

18. Properly dispose of the used waste fluid as you would dispose of used motor oil. Important: used brake fluid should NEVER be poured back into the master cylinder reservoir!

[Southern Comfort]

Seeing how you where pumping the brake pedal with the bleeder screw open, You may have to open both bleeder screws and let it set for a few minutes and let it gravity bleed. When fluid starts coming out on its own, then tighten the bleeder screw and get someone to help you bleed the calipers. Have them pump the brake pedal a few times and tell them to hold the pedal down, open the bleeder screw and let the fluid out, close the bleeder screw and then tell them to pump it and hold it again, may require several attemps to get all the air out of the lines. Never let the pedal come up while the bleeder screws are open. Also make sure you got the copper washers on your caliper. There should have been two of them. One on each side of the line fitting.
Thanks
SC

[spartfaithful]

I think I figured out the problem. I did have another person helping me for pumping the brakes. But what I was doing was releasing the fluid into the container, then not closing the bleeder screw before the next set of pumping. Now I know that the lines are probably full of air, and that it may take a few times to get fluid back in them. That also explains why the resovior never went down with fluid because the backfill of air was preventing it.