LOST BRAKING POWER AT VERY LOW SPEEDS

1SIKK_RADO · July 18, 2018

I HAVE A '16 SILVERADO 1500 5.3 W/ ABOUT 49K MILES. WHILE I WAS PARALLEL PARKING, AFTER THE 2ND PUMP, I REALIZED THE TRUCK WASNT STOPPING. I HAD TO USE BOTH LEGS TO MAKE IT STOP BEFORE HITTING THE CAR IN FRONT OF ME. WHILE DOING THAT I FELT THE ABS KICKING IN. MY BRAKE PADS AND ROTORS ARE FINE. INSTALLED HIGH PERFORMEANCE ROTORS AND PADS LIKE ABOUT 10-15K MILES AGO. BRAKE FLUID IS FINE. I DO HEAR AN ABNORMAL NOISE COMING FROM THE ENGINE AREA AT ALL TIMES. KINDA LIKE A BAD PULLEY BEARING OR SOMETHING. NOTICED IT THE DAY THE TRUCK STARTED ACTING UP. WHILE DRIVING THE BRKAES WORKING FINE IT ONLY OCCCURES WHEN I AM PARKING AND AFTER LIKE THE 2ND PUMP I HAVE NO BRAKES. ALSO IF I TAKE IT TO THE DEALER, DOES IT FALL UNDER THE POWERTRAIN WARRENTY OR BASIC?

Brianibew · July 18, 2018

Your vacuum pump has most likely failed. It is your power assist for braking. If your looking at the engine from the front, it’s the very bottom pulley to the right.

newdude · July 18, 2018

X2 on the vacuum pump. I'd be looking for oil in the hoses to and from it. If that's the case, expect to replace the pump, hoses, brake booster and master cylinder as engine oil would have contaminated the brake booster and is causing the loss of assist.

Quote

PIT5361C: Diagnostic Tip - Additional Brake Pedal Effort - (Mar 15, 2017)

Condition/Concern

In some rare situations, a customer may comment on a hard brake pedal or that increased effort is needed to depress the brake pedal. Also, in some cases a tick or ticking noise may be heard, which may sound like an exhaust manifold leak. While performing normal diagnostics, fluid may be found in the brake booster and/or the booster vacuum line.

Important: Pay close attention to the fluid and if it is determined to be engine oil, it could be coming from the vacuum pump. The vacuum pump is belt-driven and mounted to the side of the engine block. It is lubricated by pressurized engine oil.

Recommendation/Instructions

If engine oil is found, it is important the following parts are replaced. If not, the condition will return.

Vacuum Pump

Vacuum Line between the booster and the pump

Brake Booster

Master Cylinder

It would be under bumper to bumper (3/36) most likely.

EPIC CAJUN · July 18, 2018

Yep, like the two before me stated, its the vacuum pump. Just replaced mine with the lines last month.

Mine went out pulling into the driveway. Good thing the 4wheeler was in front to stop me or I would have gone through the garage wall.

Thanks GM!

truckguy82 · July 18, 2018

Dont you still have unassisted brakes if the vacuum pump goes out?

catpartsman · July 18, 2018

Why not try using the emergency brake if this happens instead of hitting something that could damage your trucks?

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diyer2 · July 18, 2018

1 hour ago, truckguy82 said:

Dont you still have unassisted brakes if the vacuum pump goes out?

Yes as far as I know.

It just takes pushing the brake pedal harder.

sk · July 18, 2018

6 hours ago, newdude said:

X2 on the vacuum pump. I'd be looking for oil in the hoses to and from it. If that's the case, expect to replace the pump, hoses, brake booster and master cylinder as engine oil would have contaminated the brake booster and is causing the loss of assist.

It would be under bumper to bumper (3/36) most likely.

This except there is a newer version of the PIT that tells them to change a few more components.

My 2015 had this happen 3 times, totally random, over about a year and a half. I argued with the dealership that I wanted this PIT done since I didn't trust driving the truck and it was a safety issue. They finally gave in and performed the PIT.

That was 4 months and 2000 miles ago and the issue hasn't happened since. As a side note I had the dreaded "it's just the normal DI tick sound" on my 5.3 but it has gone away since they changed out the vacuum pump!

newdude · July 18, 2018

1 hour ago, sk said:

This except there is a newer version of the PIT that tells them to change a few more components.

My 2015 had this happen 3 times, totally random, over about a year and a half. I argued with the dealership that I wanted this PIT done since I didn't trust driving the truck and it was a safety issue. They finally gave in and performed the PIT.

That was 4 months and 2000 miles ago and the issue hasn't happened since. As a side note I had the dreaded "it's just the normal DI tick sound" on my 5.3 but it has gone away since they changed out the vacuum pump!

The one I posted is the newest and latest one.

1SIKK_RADO · July 19, 2018

16 hours ago, newdude said:

X2 on the vacuum pump. I'd be looking for oil in the hoses to and from it. If that's the case, expect to replace the pump, hoses, brake booster and master cylinder as engine oil would have contaminated the brake booster and is causing the loss of assist.

It would be under bumper to bumper (3/36) most likely.

YUP!! That is exactly what is happening and also when the time comes to slam on my brakes bcuz of these stupid LA drivers cutting me off, the truck wont stop at all AND I have the brake pedal to the floor! I contacted my nearest chevy dealer and was told that the vacuum pump is under basic warranty (3/36). This should be safety recall in my opinion. SMH

1SIKK_RADO · July 19, 2018

14 hours ago, catpartsman said:

Why not try using the emergency brake if this happens instead of hitting something that could damage your trucks?

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when you are concentrated on parking and going at slow speeds through a parking lot and your brakes suddenly go out or someone cutting you off at the last second, you don't really think of using your e-brake bro.

newdude · July 19, 2018

7 hours ago, 1SIKK_RADO said:

YUP!! That is exactly what is happening and also when the time comes to slam on my brakes bcuz of these stupid LA drivers cutting me off, the truck wont stop at all AND I have the brake pedal to the floor! I contacted my nearest chevy dealer and was told that the vacuum pump is under basic warranty (3/36). This should be safety recall in my opinion. SMH

https://www-odi.nhtsa.dot.gov/VehicleComplaint/

https://my.gm.com/contact

Be a part of some change? They've got a phone # or you can fill it out online. I'd hope that others have possibly done this, or should be prompted to do it if they've had the issue. The more grease the squeaky wheel gets...

sk · July 19, 2018

22 hours ago, newdude said:

The one I posted is the newest and latest one.

I checked my Work Order. They actually performed revision "B" which also told the Tech to replace the Vacuum Pump Belt and the A/C Compressor Belt (see "Parts Information" section in the attached file). They must have eliminated those from rev "C" ...

PIT5361B Brakes.pdf

EPIC CAJUN · July 20, 2018

On 7/18/2018 at 7:55 AM, catpartsman said:

Why not try using the emergency brake if this happens instead of hitting something that could damage your trucks?

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E brake is the last thing going through my mind as Im pulling in my parking spot with my foot on the break peddle when all of a sudden the peddle wont move.