Topic: 06 Silverado brake problem

Posting this for my crew chief.

He has a 2006 Silverado 2500HD 4wd with a 6.0 and auto trans.  Under normal braking, just before the truck comes to a stop, the brake pedal goes to the floor and the truck barely stops.  If he has to do a hard stop, everything works and he can feel the ABS modulating.  There are no idiot lights coming on.  The fluid level is good.  He has checked the pads and rotors and the sensor on one side.

Anyone run into or hear of this issue, and what the cause is?

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Re: 06 Silverado brake problem

Never seen it on a modern vehicle but this is common of a failing master cylinder in older cars (but not the most common failure).  In short, light pressure does not seat the umbrella seals against the bore tightly but hitting it hard causes the seal to flare out enough to do its job. Most of the time if light pressure is applied at a stop and shifted from neutral or park to drive, it will creep forward when it should not and the pedal will VERY slowly sink to the floor with the same pedal pressure.  Most folks attribute this to damage done when manually bleeding the brakes and allowing the MC to pass beyond the normal stroke into the corrosion zone.

That said, I have a case of this on our spare, spare parts van and my teammate suggested it was a failed adjuster on the drums with a badly out of adjustment drum.  Another theory is a pinhole brake fluid leak (likely from rusted lines) but that will eventually show up in lost fluid.

Re: 06 Silverado brake problem

I probably am the least knowledgeable mechanic here but I have a friend with a 2002 GMC Sierra with the same issue. Here is the YouTube video he watched to solve the issue.

https://www.youtube.com/watch?v=Ld5-eoYGAiA

Re: 06 Silverado brake problem

Wheel bearing. Call me tomorrow

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Re: 06 Silverado brake problem

If it were a ABS sensor fault or loose hub bearing (super common fail)  typically the ABS goes haywire and makes the pedal pulsate/hard/high.
Sounds like the master is gone.. If ABS is still suspect all one has to do is disable the system by disconnecting ANY sensor or pump motor lead to cause it to fault/turn off.

IF the master gets changed with no resolution there is a slim chance the ABS hydraulic control unit , the fluid valve portion of the abs is bypassing but it is rare.

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Re: 06 Silverado brake problem

OnkelUdo wrote:

Never seen it on a modern vehicle but this is common of a failing master cylinder in older cars (but not the most common failure).  In short, light pressure does not seat the umbrella seals against the bore tightly but hitting it hard causes the seal to flare out enough to do its job. Most of the time if light pressure is applied at a stop and shifted from neutral or park to drive, it will creep forward when it should not and the pedal will VERY slowly sink to the floor with the same pedal pressure.  Most folks attribute this to damage done when manually bleeding the brakes and allowing the MC to pass beyond the normal stroke into the corrosion zone.

That said, I have a case of this on our spare, spare parts van and my teammate suggested it was a failed adjuster on the drums with a badly out of adjustment drum.  Another theory is a pinhole brake fluid leak (likely from rusted lines) but that will eventually show up in lost fluid.


The parking lot MC test is easy to do and usually points out the problem.  I'd go with replacing the MC.

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7 (edited by Greg S 2016-01-04 04:12 PM)

Re: 06 Silverado brake problem

A bad master will let the petal sink on a light pressure brake application as stated earlier. A hard heavy application will get the masters seals to work. This should be fairly easy to differentiate. Bench bleed the master if you decide to replace it. Or at the very least crack the masters fittings and allow the brake fluid to displace the air before moving the pedal

The ABS systems in these trucks trap air in them that can not be bled out by normal procedures, there is a ABS bleed routine to run with a scan tool. It cycles the ABS while bleeding. My Chevy 2005 3500HD needed to be bled this way after I installed a Stainless brake line kit ( lots of work) it also has the hydro-boost brakes. They use the power steering pump to servo assist the braking. Its been my experience that these hydro boost brakes can allow the pedal to nearly bottom when you stand on the petal. But at that point the ABS is in charge of the braking- not your brake pedal.

BTW, any Chevy truck of this vintage and used where it snows and salt is spread must have its brake lines looked at closely. They are notorious for failing under panic braking. The stainless kits are pricey but you will never need to replace them.

Greg

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Re: 06 Silverado brake problem

The stainless brake line kit, while a pain in the ass to replace, is the way to go.

I bought a set from a place up in Buffalo, IIRC.  Around 400 for the set, pre bent and pre flared.

I do have a rear line that i didn't install, as that one had alraedy been replaced.  it's for an extended cab short bed, IIRC.  If Randy needs it.

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Re: 06 Silverado brake problem

Copper/nickel brake line, easy to bend, flares easy and cheap. I've been using this for 6 or 7 years with zero comebacks due to corrosion. BTW I'm not guessing on the problem, I'm just going off of experience. The only master cylinder I put on one of these was because of contamination, and it was not releasing the rear brakes. I know when it's explained the way Rob did it sounds like a m/c, but I don't through parts at vehicles, not many people have money to do that's and I wouldn't be in business very long with that approach ether.

It Ain't My Fault

Re: 06 Silverado brake problem

There is a rust buildup under the front wheel speed sensors.
I worked for chevy for 20 years. We still see this all the time.
Cure is to remove the front wheel speed sensors and file the rust down. then add some rust inhibitor. (wheel bearing grease also works)
The hub/wheel bearings come with a new sensor, That way also works...but is more expensive.

Manny.

Re: 06 Silverado brake problem

Mkotzias wrote:

There is a rust buildup under the front wheel speed sensors.
I worked for chevy for 20 years. We still see this all the time.
Cure is to remove the front wheel speed sensors and file the rust down. then add some rust inhibitor. (wheel bearing grease also works)
The hub/wheel bearings come with a new sensor, That way also works...but is more expensive.

Manny.

This does work IF you can get the sensor out and IF the tone ring is not broken,......... temporarily. I think MOOG till has the lifetime warranty, you know, because nothing attracts rust like a GM. sad

It Ain't My Fault

Re: 06 Silverado brake problem

Thanks for all the input.  I'll give you an update later in the week.

"She's a brick house" 57th out of 121 and 5th in Class C, There Goes the Neighborhood 2013
"PA Posse" 21st out of 96 and 2nd in Class C, Capitol Offense 2013.
"PA Posse" 29th out of 133 and Class C WINNER, Halloween Hooptiefest 2013
"PA Posse" 33rd out of 151 and 2nd in Class C, The Real Hoopties 2013

Re: 06 Silverado brake problem

Greg S wrote:

The ABS systems in these trucks trap air in them that can not be bled out by normal procedures, there is a ABS bleed routine to run with a scan tool. It cycles the ABS while bleeding. My Chevy 2005 3500HD needed to be bled this way after I installed a Stainless brake line kit ( lots of work) it also has the hydro-boost brakes. They use the power steering pump to servo assist the braking. Its been my experience that these hydro boost brakes can allow the pedal to nearly bottom when you stand on the petal. But at that point the ABS is in charge of the braking- not your brake pedal.

Greg

Interesting ... I am having trouble getting my '02 2500 Av to bleed after doing a nearly full line swap.  is there a link to the procedure?

Jeff
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