Mechanics

CHEVY BRAKE ISSUES

2008 Chevrolet Silverado • 4WD Automatic • 85,000 miles

Im having a problem with my brakes on my 2008 Chevy Silverado 4x4. I repaced my pads, shoes, drums(one was below specs so I replaced both) and rotors(aftermarket under warranty. Easier to replace for "free"than to have them turned). I followed Haynes guide rather than change brakes the way I have always done, by removing 2/3 of brake fluid from MC and to place drums so that they do not rub shoes when rotating it(adjuster bar full open, one thread exposed). And assuming the self adjuster will do its job and adjust the shoes out every time the truck is stopped in reverse. I have a pedal that goes to the floor and I assumed Haynes screwed me and consequentially air got in the system. I purchased a Mityvac since I have noone to help me and now my problem is that I cannot get my wrench and tubing on the rear wheel cylinders at the same time to bleed the brakes. Is there a special wrench that you have to use or are there "deeper"bleeders that have a larger zerk fitting? I am using a 5/16 gear wrench and there is no room for it. I am also reading posts/threads re: ABS bleeding, etc. Will I need to do this under these circumstances?
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Centripro
March 27, 2011.




As long as you didn't top off the master cylinder in between your last brake changes there is no need to worry about the master cylinder over flowing and there is no need to drain the master cylinder down 2/3 the way down like the manual say's. As long as you didn't run the master cylinder dry I think you would be ok as far as no air in the system.I think where your problem is you never adjusted the rear brake's up after changing them.I know it say's they will adjust up by themselves but that just doesn't happen like it should. Also if the rear shoes aren't adjusted up properly you will have a low brake pedal or it will go to the floor. Because the rear shoes move till the they stop at drum that use's fluid and cause's the brake pedal to move. If the the adjuster isn't adjusted up far enough then you will get excessive brake pedal movement. The first thing I would try is adjusting the rear brakes up then see how the pedal is. The best way to adjust the rear brake's is to put the truck in neutral have only one rear drum on at time and adjust the rear shoes up till you hear a light scraping sound from the shoes rubbing on the drums. Then take the drum off and do the other side. If the pedal still is low and the pedal does fell right then bleed it. If you can't get your gear wrench box end on the bleeder then use a open end wrench or a thin wall box wrench. They also make a one man brake bleeder that goes on your bleeder screw that only allows air to come out and not allow air to be sucked back in. Let me know if you need any more information or have any other question's.
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Saturntech9
Mar 27, 2011.
Thanks Saturntech.I have a couple of problems here. First, I have already cracked the left passenger side bleeder in an attempt to MityVac the wheel cylinder(poorly, might I add) and bleed the system wheel by wheel. So I presume that there is air in the system now, if there wasn't before. Another problem is that I have the wheels back on and prefer not to take them back off. I was hoping at this point to get "deeper" bleeder screws-something I can easily get tubing and a wrench on- since I feel commited already, after craking one bleeder open already I dont have another person available(hence the MityVac purchase) and need to get this done ASAP. Where would I get a thin wall box wrench. On a Sunday(I didnt know there was such a thing and I consider myself to be a tool *****!)? No word on having to bleed the ABS or bleeding the ABS, period?

Tiny
Centripro
Mar 27, 2011.
As far as the thin wall box wrench I was talking about just finding a whtch that has a thin wall box end some can be thicker then others like your gear wrench one. It would be in your best intrest to remove the rear wheels and adjust the rear brakes iy really makes a difference in your pedal feel and stopping. They also have that one man bleeder hose so you can bleed it by yourself so you haq

Saturntech9
Mar 27, 2011.
So you have abs?

Saturntech9
Mar 27, 2011.
ABS? Yeah.2008. Was in the original post. How does removing the rear wheels help me in adujusting the brakes. And at that, having one drum off while working on the other?

Tiny
Centripro
Mar 27, 2011.
Because with your truck is rear wheel drive and the other drum will cause drag and make it hard to adjust and can throw your adjustment off. That is how I adjust them and it works for me.I find if the other drum is on or the wheels it makes it hard to tell when the drum starts draging againist the shoes.I cant get you bleed info right now iam in church right now on intermission. As soon as I get

Saturntech9
Mar 27, 2011.
As soon as I get home I will get you that info usually 12-12: 30Pm california time.

Saturntech9
Mar 27, 2011.
I posted both the automated abs bleed procedure's but that take's a scan tool with the correct software.I also posted the manual bleed procedure. Let me know if you have anymore question's or concern's.

Antilock Brake System Automated Bleed

Notice: Avoid spilling brake fluid onto painted surfaces, electrical connections, wiring, or cables. Brake fluid will damage painted surfaces and cause corrosion to electrical components. If any brake fluid comes in contact with painted surfaces, immediately flush the area with water. If any brake fluid comes in contact with electrical connections, wiring, or cables, use a clean shop cloth to wipe away the fluid.

Important: The base hydraulic brake system must be bled before performing this automated bleeding procedure. If you have not yet performed the base hydraulic brake system bleeding procedure, refer to Hydraulic Brake System Bleeding before proceeding.

1. Install a scan tool to the vehicle.
2. Start the engine and allow the engine to idle.
3. Using the scan tool, begin the automated bleed procedure.
4. Follow the instructions on the scan tool to complete the automated bleed procedure. Apply the brake pedal when instructed by the scan tool.
5. Turn the ignition OFF.
6. Remove the scan tool from the vehicle.
7. Fill the brake master cylinder reservoir to the maximum-fill level with Delco Supreme 11, GM P/N 12377967 (Canadian P/N 992667), or equivalent DOT-3 brake fluid from a clean, sealed brake fluid container.
8. Bleed the hydraulic brake system.
9. With the ignition OFF, apply the brakes 3-5 times, or until the brake pedal becomes firm, in order to deplete the brake booster power reserve.
10. Slowly depress and release the brake pedal. Observe the feel of the brake pedal.
11. If the brake pedal feels spongy, repeat the automated bleeding procedure. If the brake pedal still feels spongy after repeating the automated bleeding procedure inspect the brake system for external leaks. Refer to Brake System External Leak Inspection. See: Hydraulic System\Testing and Inspection\Component Tests and General Diagnostics\Brake System External Leak Inspection
12. Turn the ignition key ON, with the engine OFF; check to see if the brake system warning lamp remains illuminated.
13. If the brake system warning lamp remains illuminated, DO NOT allow the vehicle to be driven until it is diagnosed and repaired. Refer to Symptoms - Hydraulic Brakes. See: Hydraulic System\Testing and Inspection\Symptom Related Diagnostic Procedures
14. Drive the vehicle to exceed 13 km/h (8 mph) to allow ABS initialization to occur. Observe brake pedal feel.
15. If the brake pedal feels spongy, repeat the automated bleeding procedure until a firm brake pedal is obtained.

Hydraulic Brake System Bleeding (Manual)
Caution: Refer to Brake Fluid Irritant Caution.

Notice: Refer to Brake Fluid Effects on Paint and Electrical Components Notice.

Notice: When adding fluid to the brake master cylinder reservoir, use only Delco Supreme 11(R), GM P/N 12377967 (Canadian P/N 992667), or equivalent DOT-3 brake fluid from a clean, sealed brake fluid container. The use of any type of fluid other than the recommended type of brake fluid, may cause contamination which could result in damage to the internal rubber seals and/or rubber linings of hydraulic brake system components.

1. Place a clean shop cloth beneath the brake master cylinder to prevent brake fluid spills.
2. With the ignition OFF and the brakes cool, apply the brakes 3-5 times, or until the brake pedal effort increases significantly, in order to deplete the brake booster power reserve.
3. If you have performed a brake master cylinder bench bleeding on this vehicle, or if you disconnected the brake pipes from the master cylinder, you must perform the following steps: 1. Ensure that the brake master cylinder reservoir is full to the maximum-fill level. If necessary add Delco Supreme 11(R), GM P/N 12377967 (Canadian P/N 992667), or equivalent DOT-3 brake fluid from a clean, sealed brake fluid container. If removal of the reservoir cap and diaphragm is necessary, clean the outside of the reservoir on and around the cap prior to removal.
2. With the rear brake pipe installed securely to the master cylinder, loosen and separate the front brake pipe from the front port of the brake master cylinder.
3. Allow a small amount of brake fluid to gravity bleed from the open port of the master cylinder.
4. Reconnect the brake pipe to the master cylinder port and tighten securely.
5. Have an assistant slowly depress the brake pedal fully and maintain steady pressure on the pedal.
6. Loosen the same brake pipe to purge air from the open port of the master cylinder.
7. Tighten the brake pipe, then have the assistant slowly release the brake pedal.
8. Wait 15 seconds, then repeat steps 3.3-3.7 until all air is purged from the same port of the master cylinder.
9. With the front brake pipe installed securely to the master cylinder, after all air has been purged from the front port of the master cylinder, loosen and separate the rear brake pipe from the master cylinder, then repeat steps 3.3-3.8.
10. After completing the final master cylinder port bleeding procedure, ensure that both of the brake pipe-to-master cylinder fittings are properly tightened.

4. Fill the brake master cylinder reservoir with Delco Supreme 11(R), GM P/N 12377967 (Canadian P/N 992667), or equivalent DOT-3 brake fluid from a clean, sealed brake fluid container. Ensure that the brake master cylinder reservoir remains at least half-full during this bleeding procedure. Add fluid as needed to maintain the proper level. Clean the outside of the reservoir on and around the reservoir cap prior to removing the cap and diaphragm.
5. Install a proper box-end wrench onto the RIGHT REAR wheel hydraulic circuit bleeder valve.
6. Install a transparent hose over the end of the bleeder valve.
7. Submerge the open end of the transparent hose into a transparent container partially filled with Delco Supreme 11(R), GM P/N 12377967 (Canadian P/N 992667), or equivalent DOT-3 brake fluid from a clean, sealed brake fluid container.
8. Have an assistant slowly depress the brake pedal fully and maintain steady pressure on the pedal.
9. Loosen the bleeder valve to purge air from the wheel hydraulic circuit.
10. Tighten the bleeder valve, then have the assistant slowly release the brake pedal.
11. Wait 15 seconds, then repeat steps 8-10 until all air is purged from the same wheel hydraulic circuit.
12. With the right rear wheel hydraulic circuit bleeder valve tightened securely, after all air has been purged from the right rear hydraulic circuit install a proper box-end wrench onto the LEFT REAR wheel hydraulic circuit bleeder valve.
13. Install a transparent hose over the end of the bleeder valve, then repeat steps 7-11.
14. With the left rear wheel hydraulic circuit bleeder valve tightened securely, after all air purged from the left rear hydraulic circuit, install a proper box-end wrench onto the RIGHT FRONT wheel hydraulic circuit bleeder valve.
15. Install a transparent hose over the end of the bleeder valve, then repeat steps 7-11.
16. With the right front wheel hydraulic circuit bleeder valve tightened securely, after all air has been purged from the right front hydraulic circuit, install a proper box-end wrench onto the LEFT FRONT wheel hydraulic circuit bleeder valve.
17. Install a transparent hose over the end of the bleeder valve, then repeat steps 7-11.
18. After completing the final wheel hydraulic circuit bleeding procedure, ensure that each of the 4 wheel hydraulic circuit bleeder valves are properly tightened.
19. Fill the brake master cylinder reservoir to the maximum-fill level with Delco Supreme 11(R), GM P/N 12377967 (Canadian P/N 992667), or equivalent DOT-3 brake fluid from a clean, sealed brake fluid container.
20. Slowly depress and release the brake pedal. Observe the feel of the brake pedal.
21. If the brake pedal feels spongy, repeat the bleeding procedure again. If the brake pedal still feels spongy after repeating the bleeding procedure, perform the following steps: 1. Inspect the brake system for external leaks. Refer to Brake System External Leak Inspection (See: Hydraulic System\Testing and Inspection\Component Tests and General Diagnostics\Brake System External Leak Inspection).
2. Pressure bleed the hydraulic brake system in order to purge any air that may still be trapped in the system.

22. Turn the ignition key ON, with the engine OFF. Check to see if the brake system warning lamp remains illuminated.

Important: If the brake system warning lamp remains illuminated, DO NOT allow the vehicle to be driven until it is diagnosed and repaired.

23. If the brake system warning lamp remains illuminated, refer to Symptoms - Hydraulic Brakes (See: Hydraulic System\Testing and Inspection\Symptom Related Diagnostic Procedures\Symptoms - Hydraulic Brakes).

Saturntech9
Mar 27, 2011.
Awesome! That is alot of good information. Is that out of the shop manual? Im "hot" that Haynes doesn't go into any detail about ABS bleeding. I am kicking myself for not ordering the Scantool that I have been eyeballing for awhile now. Are you familiar with Scantool off scantool. Net and if so, what do you think about it from a professional standpoint. If you don't mind. I know it is offtopic and I appreciate the info provided.

Tiny
Centripro
Mar 28, 2011.
The info I gave you is from alldata it's a online repair manual it requires a monthly subscription or they sell a limited pass to it. That's what the moderators use on this website to help answer question's. Its one of the online repair manuals the repair shops use it's my favorite online manual. It's expensive for a do it your selfer to do the monthly subscription though.I have found that the haynes and chilton manuals are pretty general and don't go into details about a lot thing's. They generalize a lot of things in there.I have seen they sell factory manuals on cd roms i'm not sure if they have them for your truck though but they show exploded views stuff like that. Honestly I have never used the pc based do it your selfer software with the obd2 connector that works with your laptop.I have used the tech2 scan tool that gm dealers use and I love it since it has all the software to do all the special tests to go thru the factory trouble trees perform special functions and is able to read all the cars computers.I used other do it your selfer scan tools as well as the gm factory service stall.I know you can save money by getting the software for your laptop I just have never used it to give my review of it. The one your looking at says it has a 90 day money back return so that might be something to check out. What your looking for is code reading code clearing live data read out graphing the sensors is nice. Also live data recording is nice as well. Being able to read if the monitors are set or not etc. Let me know if you have anymore questions I would be more then happy to answer for you.

Saturntech9
Mar 28, 2011.

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