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2001 Sonoma 4x4 Mechanic can't fix


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Sonoma4x4
New User

Mar 26, 2014, 2:01 PM

Post #1 of 8 (2285 views)
2001 Sonoma 4x4 Mechanic can't fix Sign In

OK, first thank you all who are reading this for your time and effort, I am aware how valuable time is.

So here is my problem: 2001 GMC Sonoma 4x4 w/ ABS

A few weeks ago I had to slam on my brakes to avoid an accident. Since then I have no rear brakes (only have pedal near floor).

I am loosing fluid from somewhere that I can't find and neither could my mechanic. He said he couldn't find the leak if the master cylinder won't push pressure to the rear brakes. He said he tried to bleed it from the rear and from the rear lines of the master cylinder with no luck of getting any fluid.

I can say when the truck is off the brakes will pump up hard, and as soon as I start my truck I lose all pressure again except what I had before (only brakes at the floor).

If the master cylinder ins't pushing fluid out to the rear line then where could my fluid be going? Someone said possibly out the master cylinder into the booster, but this seems unlikely to me that I don't find any fluid under the booster or where the master cylinder connects to the booster.

Two lines come out the MC and go to (what I believe is) the ABS box. Two lines come out of the ABS and go to the front and one comes out and goes to the rear (from what I can see anyways). There is deff two lines in and three going out.

Has anyone heard of this issue or does anyone have a place me to start checking?

Also, I have NO ABS LIGHT on and the brake light only comes on when I'm low on fluid. I have went through a large container of brake fluid in about 35-50 miles.

THANKS YOU EVERYONE WHO CAN HELP!!!!!!


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Mar 26, 2014, 2:15 PM

Post #2 of 8 (2274 views)
Re: 2001 Sonoma 4x4 Mechanic can't fix Sign In

I sure don't know how to second guess a hands on mechanic that can't isolate a leak that bad but some ideas that are just ideas:


Fluid unseen and consuming it probably is going into booster if nothing found elsewhere. Jeez, bet it master is just loosened it will show fluid coming out the firewall end right away.


Generally the part of master nearest the booster and lines there are directed to front brakes but can't know where it's routed for sure for a truck and ABS involved so easily.


It probably is the master that gave out with a hard stop. That's only probably and even if proven so will take proper sequence of bleeding to get it back to correct so suggest you find another tech with the equipment for this,


T



Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Mar 26, 2014, 2:36 PM

Post #3 of 8 (2268 views)
Re: 2001 Sonoma 4x4 Mechanic can't fix Sign In

Tom is right. If you truly are losing fluid, it shouldn't be that hard to find.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



kev2
Veteran
kev2 profile image

Mar 26, 2014, 2:39 PM

Post #4 of 8 (2267 views)
Re: 2001 Sonoma 4x4 Mechanic can't fix Sign In

 do not trust the bulb alone - scan for ABS codes...


some things I have seen- some may help other may not apply- getting the gang thinking-
>pull back the carpet on drivers side fluid can puddle on floor from a bad MS
>The brake fluid actually being drawn into the brake booster- and consumed by eng vacuum.
>There is a small PIN on the proportioning valve that moves to isolate front from rear brake system...


Sonoma4x4
New User

Mar 26, 2014, 3:08 PM

Post #5 of 8 (2261 views)
post icon Re: 2001 Sonoma 4x4 Mechanic can't fix Sign In

Well I just realized my in law has my wrenches so after being fed up I just took it to a local shop that specializes in just brakes with free estimates and dropped it off to have it looked at tomorrow. The guy was telling me it was prob leaking into booster also. I will make sure to post the results when I get them to help someone that might have future problems.

500$ in tires, a new distributor/rotor/cap, and now this...will it ever end????!!!! Thank you all for the responses and for your time!


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Mar 26, 2014, 3:37 PM

Post #6 of 8 (2260 views)
Re: 2001 Sonoma 4x4 Mechanic can't fix Sign In


Quote
500$ in tires, a new distributor/rotor/cap, and now this...will it ever end???


The truck is 13 years old now. You have to expect some repairs.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Sonoma4x4
New User

Mar 26, 2014, 8:02 PM

Post #7 of 8 (2240 views)
Re: 2001 Sonoma 4x4 Mechanic can't fix Sign In


In Reply To

Quote
The truck is 13 years old now. You have to expect some repairs.


Yep I know haha, it just all hit me at once. :)



nickwarner
Veteran / Moderator
nickwarner profile image

Mar 26, 2014, 10:11 PM

Post #8 of 8 (2237 views)
Re: 2001 Sonoma 4x4 Mechanic can't fix Sign In

Breakdowns come when you can least afford it. Its kinda related to Murphy's Law






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