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Stiff brake pedal?

Tiny
BIGMAX
  • MEMBER
  • 2018 CHEVROLET COLORADO
  • 2.5L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 80,000 MILES
Changed front brake pads after hearing scraping sound. After getting new pads installed, I got a friend to assist in bleeding brake lines. The first pump was extremely stiff and never eased any. Checked and thought the brake booster check valve might be faulty. With engine running, pulled the valve from the rubber grommet. No change in engine idle, and no vacuum on the vacuum hose. Please advise.
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Saturday, June 3rd, 2023 AT 1:04 PM

17 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi,

If there is no vacuum, either the hose has come disconnected from the vacuum pump, the electrical connector at the vacuum sensor is disconnected, or the hose is broken.

I attached a pic below showing the hose. Check to see if it is connected and confirm there are no cracks or damage to it.

Let me know.

Joe
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Saturday, June 3rd, 2023 AT 10:48 PM
Tiny
BIGMAX
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  • 18 POSTS
No picture attached but I will check the hose and connection. Checked vacuum hose and grommets. No leaks and Elec, connection seems good. Got a friend coming today and we plan to bleed the master cylinder and brake lines, to assure no air in lines.
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Sunday, June 4th, 2023 AT 6:09 AM
Tiny
BIGMAX
  • MEMBER
  • 18 POSTS
We just finished bleeding the master cylinder ad then the lines (in proper order) and all is well good pedal but not tight as before. Road tested and good to go. Many thanks.
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Sunday, June 4th, 2023 AT 11:31 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi,

Thank you for the update. I'm glad you got it taken care of.

Feel free to come back anytime in the future if you have questions.

Take care,

Joe
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Sunday, June 4th, 2023 AT 9:28 PM
Tiny
BIGMAX
  • MEMBER
  • 18 POSTS
The problem has re-occurred. Brake pedal stiff again but not quite as stiff as before. Please advise.
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Tuesday, June 6th, 2023 AT 6:52 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Are you getting vacuum to the booster? Did anything come disconnected? It must be something close to the MC if it started working after you did the bleed procedure.

Let me know.

Joe
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Tuesday, June 6th, 2023 AT 8:22 PM
Tiny
BIGMAX
  • MEMBER
  • 18 POSTS
Finally replaced the vacuum control valve. I'm still getting stiff pedal. Would it possibly be the master cylinder? Booster?
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Tuesday, June 13th, 2023 AT 8:41 AM
Tiny
BIGMAX
  • MEMBER
  • 18 POSTS
Every little while I get brake message.
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Tuesday, June 13th, 2023 AT 8:43 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi,

Of the two, the booster and master cylinder, the booster can cause it. Have you checked to see if holds a vacuum?

What message are you getting? Is the vacuum pump working properly?

Let me know.

Joe
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Tuesday, June 13th, 2023 AT 7:26 PM
Tiny
BIGMAX
  • MEMBER
  • 18 POSTS
"SERVICE BRAKE ASSIST" is the message that I get. How to check the vacuum? Does the 2018 Colorado have a mechanical vacuum pump? If so. Where is it located?
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Wednesday, June 14th, 2023 AT 10:56 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi,

It does have a brake booster pump. It's located at the front of the engine. Take a look at the pic I attached below and let me know if you can locate it.

Note, there is a quick connection on the vacuum supply hose to the booster. Make sure it is connected and not damaged.

Let me know.

Joe

See pic below.
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Wednesday, June 14th, 2023 AT 10:28 PM
Tiny
BIGMAX
  • MEMBER
  • 18 POSTS
After much frustration, have changed vacuum control valve, master cylinder and booster. Down to replacing vacuum pump. Removed the 3 10mm bolts and wouldn't budge. Removed all valve cover bolts and got the cover loose but the pump will not come off the cam. Please advise on how to remove vacuum pump, please.
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Saturday, July 22nd, 2023 AT 4:14 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi,

It sounds like you've been busy. I'm not sure why the valve cover was removed. The pump is removable without doing that.

Regardless, I attached the directions below for the removal and installation of the power brake booster pump.

Let me know if this helps.

Take care,

Joe

See pics below.
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Saturday, July 22nd, 2023 AT 9:29 PM
Tiny
BIGMAX
  • MEMBER
  • 18 POSTS
The vacuum pump was Seized at the valve cover opening. That is why I removed the valve cover. Once removed, one side of the slotted connector on the vacuum pump was broken off. Looked and looked for that piece with no result, Awaiting new vacuum pump.
Seal to install the new OEM pump. Thanks for the pics however, the vacuum pump on 2018 Colorado is on the back of the valve cove next to the firewall with about 3 inches of working room. That is the reason for removing the valve cover. Lol. Will follow up once new pump is installed. Again, thanks for your help!
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Monday, July 24th, 2023 AT 2:10 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi,

Thanks for the update. It sounds like you have the same kind of luck as I do. LOL Also, I double checked my manual and apparently, it's wrong. The pics I attached above are what it provides.

Regardless, I hope things start getting easier. Take care and I look forward to hearing the results.

Joe
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Monday, July 24th, 2023 AT 8:55 PM
Tiny
BIGMAX
  • MEMBER
  • 18 POSTS
Well, parts finally arrived, got the new OEM vacuum pump installed. Test drive proved positive, and the brakes are now working properly. It was a real pain but I'm glad it all worked out! Can't remember when I've had so much fun, Thanks again for the assistance. After replacing the vacuum check valve, booster, master cylinder and vacuum pump it had better have worked. At least I have completely new brake system, lol.
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Wednesday, July 26th, 2023 AT 11:05 AM
Tiny
JACOBANDNICKOLAS
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Hi,

Thanks for the update and that is great news. I'm glad the problem has been resolved.

Take care of yourself and feel free to come back anytime in the future.

Joe
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Wednesday, July 26th, 2023 AT 8:03 PM

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