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What I did:

I have a 1997 GMC Jimmy that I replaced the power brake booster and rebuilt the rear drum brakes (new brake shoes, springs, and wheel cylinders). I bled the rear drums since I replaced the wheel cylinders. I did not have to remove any lines from the master cylinder in order to remove the power brake booster / install the new one so I did not bleed the front brakes. I also topped off the brake fluid in the master cylinder.

The problem:

When I took it for a test drive, every once in a while the brake pedal would stick to where I pushed it to and there would be a squealing kind of noise coming from the area of the brake booster. I took the car on about 5 test drives and every time it would do it at least once. Sometimes it would happen when I slam on the brakes and sometimes it wouldn't. Sometimes it would happen when I was just pressing regularly and again, other times it wouldn't. The easiest way I found to get the pedal to come back up to normal position was to put the car in park and pump the pedal.

My question:

What could be causing this? Is the power brake booster that I was sent defective or is it something else? Any suggestions or ideas would be greatly appreciated!

  • Welcome to Motor Vehicle Maintenance & Repair! This sounds most like there is an issue with the master cylinder and/or the booster mechanism. I couldn't tell you what it is, exactly, but that's where I'd look first for answers. Maybe someone on here has experienced this type of issue before and can give you a better clue than I can. – Pᴀᴜʟsᴛᴇʀ2 Mar 29 at 15:20
  • Sounds like a defective booster or incorrect installation. – Moab Mar 30 at 20:56
  • I know it's a pain but sounds like a wheel cylinder isn't retracting back into the bore. Air in the lines doesn't cause a pedal to stick down. Isolate the side that's sticking and check it. Remanufactured cylinders tend to be garbage, are they OEM? – geoO Apr 1 at 14:01
  • Thanks everyone for your help! I have another booster on the way so I can figure out if it is the booster or something else. Also @geoO the wheel cylinders are new AcDelco (OEM for GM). – AFatBunny Apr 1 at 14:07
  • If you solve it come back you can make an answer to your own question and then upvote it. Pictures would be nice! – geoO Apr 1 at 14:12
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It appears that the issue was a faulty power brake booster. I removed and returned the first one that Cardone sent me and installed the second one. It's been about a week and a half and there is no longer an issue leading me to believe that the first booster that they sent me was defective.

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  • I get a lot of remanufactured parts with defects. It's a scandal and a trap for the unwary DIYer. Sometimes, not always, it's best to buy from the dealer, because their parts go will into warranteed cars, and is likely to be a specific, operational part. Not some no-name core with a "universal" fit that is used to replace a group of OEM part numbers. Cardone actually on my "junk" list. – geoO Jul 13 at 12:24

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