Chevy

Chevrolet Repair Questions? Ask a Chevy Mechanic for Answers ASAP

Ask an Expert,
Get an Answer ASAP!

Chevrolet Avalanche 1500 Z71: I have a 2004 chevy avalance…

Customer Question
I have a 2004 chevy...
I have a 2004 chevy avalance all four brakes lock up .they have change everything but master cyclinder and fluid and still locks up all four wheels.
Submitted: 3 years ago.Category: Chevy
Show More
Show Less
Ask Your Own Chevy Question
Answered in 3 hours by:
6/22/2015
Chevy Mechanic: Clayso, Master Automobile Technician replied 3 years ago
Clayso
Clayso, Master Automobile Technician
Category: Chevy
Satisfied Customers: 880
Experience: ASE Master Certified Automobile Technician. 30 Years Experience.
Verified
Hi There, I'm Clayso a certified master automobile technician with 30 years of automotive repair and diagnostic experience and I'm here to help with this problem. Additional services may be offered for detailed information.
From your description it sounds like the Hydraulic Assist/hydro boost assembly is continuing to apply pressure when the brakes are released. When the brakes are cool and not locked up. Start and run the engine to operating temperature. Hold the engine at about 2000 rpm. Turn and hold the steering wheel all the to the left or right for a couple of seconds. Return the vehicle to idle, put it in gear and see if the brakes are now locked up. If the brakes are not locked up the vehicle will have to be driven until the brakes do lockup.
When the brakes are locked up loosen the two nuts that hold the master cylinder to the booster a couple of turns each, if the brakes release the hydraulic booster is at fault. If the brakes do not release with the master cylinder loose from the booster loosen the brake lines at the master cylinder. If the brakes are now free the master cylinder is maintaining the pressure and is at fault.
Brake Assist System Description and Operation (Hydraulic Assist)
System Component Description
The brake assist system consists of the following:
Brake Pedal: Receives, multiplies and transfers brake system input force from driver.
Brake Pedal Push rod: Transfers multiplied input force received from brake pedal to brake booster.
Hydraulic Brake Booster: Uses power steering fluid pressure to decrease effort required by driver when applying brake system input force. When brake system input force is applied, pressurized power steering fluid is admitted to the rear of an apply piston, providing a decrease in brake pedal effort required. When input force is removed, pressurized power steering fluid is blocked off from the piston.
Power Steering System: Supplies pressurized power steering fluid used by hydraulic brake booster to decrease brake pedal effort.
System Operation: Brake system input force is multiplied by the brake pedal and transferred by the pedal push rod to the hydraulic brake master cylinder. Effort required to apply the brake system is reduced by the hydraulic brake booster.
I hope this information is helpful to you.
Should you have any questions please let me know.
Positive ratings are greatly appreciated.
Thanks so much.
Ask Your Own Chevy Question
Chevy Mechanic: Clayso, Master Automobile Technician replied 3 years ago
Hi There,
You last viewed this thread on June 22nd, and I hope the information I gave was helpful. Let me know if you have followed through with my recommendations. If you have any questions, please let me know.
Thanks so much.
Ask Your Own Chevy Question
Customer reply replied 3 years ago
THANK you the mechanic changed the master cylinder said that was the problem.
Chevy Mechanic: Clayso, Master Automobile Technician replied 3 years ago
You're welcome. I'm glad the problem is solved. If it's not to much to ask would you rate my answer in a positive manner.
Thanks so much.
Ask Your Own Chevy Question
Was this answer helpful?

How JustAnswer works

step-image
Describe your issueThe assistant will guide you
step-image
Chat 1:1 with a chevy mechanicLicensed Experts are available 24/7
step-image
100% satisfaction guaranteeGet all the answers you need
Ask Clayso Your Own Question
Clayso
Clayso
Clayso, Master Automobile Technician
Category: Chevy
Satisfied Customers: 880
880 Satisfied Customers
Experience: ASE Master Certified Automobile Technician. 30 Years Experience.

Clayso is online now

A new question is answered every 9 seconds

How JustAnswer works:

  • Ask an ExpertExperts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional AnswerVia email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction GuaranteeRate the answer you receive.

JustAnswer in the News:

Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.

What Customers are Saying:

I was having a terrible problem with the wheel bearings on my 98 Chevy Cavalier and I suspect that using this website saved me plenty of time and money.

Todd LRochester NY

Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help.

Mary C.Freshfield, Liverpool, UK

This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!!

AlexLos Angeles, CA

Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult.

GPHesperia, CA

I couldn't be more satisfied! This is the site I will always come to when I need a second opinion.

JustinKernersville, NC

Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around.

EstherWoodstock, NY

Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know.

RobinElkton, Maryland

< Previous | Next >

Meet the Experts:

GM Tech (Cam)

GM Tech (Cam)

Chevy Technician

15,756 satisfied customers

GM Grand Master Technician 2007. 14 years experience.

Gary

Gary

Chevy Technician

9,642 satisfied customers

15 years GM master tech

Tim&#039;s Auto Repair

Tim's Auto Repair

mechanic

8,884 satisfied customers

Have owned a repair shop for 25 yrs.

Dave Nova

Dave Nova

Chevrolet Technician

7,092 satisfied customers

ASE Master Certification. GM World Class Certification

John

John

Master A.S.E Automotive technician

4,071 satisfied customers

A.S.E MasterTechnician A1-A8 w/L1,38 years experience General Motors Master Technician

Don - Mo Lurch

Don - Mo Lurch

Auto Mech / Electronics

2,953 satisfied customers

Chevrolet Cert., Heavy Line Mech, Race Shop Owner, Mobile Electronics.

Ron Z.

Ron Z.

- Chevy Tech -

2,836 satisfied customers

18+yrs experience. State Inspector and Chevy Diagnostics

< Previous | Next >

Related Chevy Questions
I have a 2002 gmc 2500 hd diesel and has all new brakes,all
Hello, I have a 2002 gmc 2500 hd diesel and has all new brakes,all disc, new calipers,new master cyclinder,new aux booster. But they still don't stop very well. … read more
Gary
Gary
Chevy Technician
Vocational, Technical or Trade Scho
9,642 satisfied customers
1996 chevy blazer brakes locking up, have slid though intersections.
1996 chevy blazer brakes locking up, have slid though intersections. When they lock up I hear the ABS come on and the rear brake drums get very hot while driving. Any ideas? Thanks Ron… read more
Gary
Gary
Chevy Technician
Vocational, Technical or Trade Scho
9,642 satisfied customers
2001 chevy 2500hd, 4 wheel disk, power steering booster, all
2001 chevy 2500hd, 4 wheel disk, power steering booster, all new stainless steel lines, calipers, rotors and pads. After about a week of use all four brakes lock up while driving. Noticed the brake ma… read more
Gary
Gary
Chevy Technician
Vocational, Technical or Trade Scho
9,642 satisfied customers
Chevrolet Silverado 2500 HD: I Have a 2003 Chevy 2500 HD With
I Have a 2003 Chevy 2500 HD With a Duramax, The brakes Feel like they are applied on all for wheels all the time and the master cylinder is leaking, This just happened out the blue while I was driving… read more
ASEMaster35yrs
ASEMaster35yrs
Vocational, Technical or Trade Scho
1,314 satisfied customers
Chevrolet K2500 4x4: My brakes are locking up on my 2003 Chevy
My brakes are locking up on my 2003 Chevy K2500 with Duromax diesel engine. It started with rust out of the brake lines causing loss of brake fluid. Had to be towed into the local repair. After replac… read more
Gary
Gary
Chevy Technician
Vocational, Technical or Trade Scho
9,642 satisfied customers
Chevrolet Trailblazer LT: 2004 chevy trailblazer LT when making
2004 chevy trailblazer LT when making a sharp turn the back wheel appears to be digging in and skipping across the groung, vehicle is in 2hi… read more
GM Tech (Cam)
GM Tech (Cam)
Chevy Technician
Vocational, Technical or Trade Scho
15,756 satisfied customers
Chevy pickup Cheyenne 10: New master cyclinder installed, l977
New master cyclinder installed, l977 chevy pickup, after replacing right rear bad wheel cylinder--leaking fluid. Bench bled new MC then tryed to pump brake fluid to rear but fluid won't move thru brak… read more
MrDiag
MrDiag
Consultant
70 satisfied customers
Blazer: brake line to the rear brakes broke...abs unit..rear wheels
I have a 1997S10 Blazer. The brake line to the rear brakes broke. I replaced it from the abs unit all the way back, and I can't get fluid to the rear wheels. I tried ti bleed them and i still didn't g… read more
AMEDEE
AMEDEE
AUTOMOTIVE TECHNICIAN
Vocational, Technical or Trade Scho
9,105 satisfied customers
Wheels..cars..neutral car stays in place like im pressing the brakes
new master and power booster all wheels on 77 vette are locked with cars running.next day they are free and not lockedup. Everything on this car is ground up restoration and new.when car is running ev… read more
Jan Andersson
Jan Andersson
Master Tech
Bachelor's Degree
3 satisfied customers
99 chevy blazer: 4x4..cyclinder..brake lines and bled brakes..peddle
99 chevy blazer 4x4, replaced master cyclinder, brake lines and bled brakes about 50 times and the peddle still goes to the floor what else could be the problem?… read more
heavy_chevy_396
heavy_chevy_396
Vocational, Technical or Trade Scho
2,518 satisfied customers
2004 avalanche 1500: brakes lock..wheels..problem seemed..calipers
i have a 2004 avalanche 1500 4x4 where the brakes lock on all four wheels. The problem seemed to occur after the hydro booster was replaced. The new hydro booster was insalled, the calipers were clean… read more
BOBBYSS
BOBBYSS
TECHNICIAN/ADVISOR
Associate Degree
8,343 satisfied customers
1978 chevy: brake line, now spongy peddle and light stays..pin..bleed
1978 chevey half ton truck, replaced back brake line, now spongy peddle and light stays on . Tried bleeding, clamped in pin on combination valve, bleed back first, low pressure fluid just seeps out of… read more
Gary
Gary
Chevy Technician
Vocational, Technical or Trade Scho
9,642 satisfied customers
2001 Chevy Blazer: brake pedal..all four wheels..rotors..hoses
2001 Chevy Blazer. The brake pedal is mushy. We checked all four wheels, the pads rotors, hoses and lines are all in great condition. We changed the brake the brake fluid and bled the system but now t… read more
ase_master327
ase_master327
Owner & Student
High School or GED
3,214 satisfied customers
2003 chevy 2500hd front brakes locking up when driving. relieve
2003 chevy 2500hd front brakes locking up when driving. relieve the fluid and it drive for a few more minutes and the same thing happens again. help… read more
eauto
eauto
self employed
High School or GED
74 satisfied customers
10 blazer: the master cyclinder gasket is melted and i..flush..abs
ok i accdiently put power steering fluid in my master cyclinder i have a 95 s-10 blazer now the master cyclinder gasket is melted and i have no brakes i was wondering if i need to do anything special … read more
zzdaryl
zzdaryl
Lead Auto Tech
Some college and advanced training
4 satisfied customers
97 chevy astro: on the highway..locking..van drivers side rear..master
I was driving my 97 chevy astro on the highway and noticed that the van was feeling like is was locking yp on me (loosing power) I also noticed that there was smoke coming from the back end. I pulled … read more
Wrenchtech
Wrenchtech
Vocational, Technical or Trade Scho
616 satisfied customers
Chevy: ton..the master cyclinder, the brake pedal holds..few seconds
I''m changing the brake booster on my 1/2 ton chevy pick up, having problems getting it off! How do I get it removed to put the new one on? I''ve changed the master cyclinder, the brake pedal holds fo… read more
Wrenchtech
Wrenchtech
Vocational, Technical or Trade Scho
616 satisfied customers
98 CHEVY: WHEEL DRIVE AND THE BRAKE PEDAL GOES TO THE FLOOR I..BOOSTER
I HAVE 98 CHEVY 1500XXXXXAND THE BRAKE PEDAL GOES TO THE FLOOR I HAVE REPLACED EVERYTHING BUT THE BOOSTER AND LINES DO YOU KNOW WHAT I SHOULD DO.… read more
joseph carrillo
joseph carrillo
automotive drivability tech
Vocational, Technical or Trade Scho
314 satisfied customers
Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Show MoreShow Less

Ask Your Question

x