seanomatic

First off...

2006 HHR 65,000 miles.
#1 No air in lines (fluid replaced & system bled)
#2 Fresh pads up front and life left in rear shoes
#3 Brakes feel normal when engine off, once engine started pedal goes almost all the way to the floor and stays that way during driving.

The issue happened suddenly with no lead up of spongy braking, etc. precipitating this problem.

Anyone have any experience with a similar occurrence and a solution? Seems to be a lot of people experiencing problems with pulsating pedal and shuddering on downgrades (myself included) - supposedly caused by pad material deposits on rotors and misdiagnosed as warped rotors - but that's not what I'm talking about here. My mechanic is slightly at a loss and could try replacing the master but as there is no aftermarket option I would have to pay for it wether or not the mc is the culprit.

HELP HELP HELP!

I'm a newbie on the forum, thanks in advance for any info and help.

Greybeard999

Welcome to the forum.......

My first thought was master cylinder from past experience with older cars, but this is the first I've heard of it in an HHR so I don't know if it applies. Can your mechanic pressure check the MC before replacing it?

harleysshhr

If I'm reading you post correctly the pedal goes down and stays down without going completely to the floor and while still having some sort of stopping ability. The pedal height is in most causes directly related to the adjustment of the rear brakes. Try adjusting the rear brakes. If that doesn't help you might have and air displacement problem with the front braking system requiring another bleeding of the front only.

donbrew

Top of head: Did you bleed all the way around? If you step on the pedal before starting the engine the pedal should go almost to the floor upon starting the engine, but then pump back up. Check for cracked/broken/disconnected vacuum lines to the booster. Check the rear adjustment (the parking brake should only pull up a few clicks). It is my (and only my opinion) that you should not bleed the brakes if you are only replacing pads, a huge number of people disagree with me. But, poor/incorrect bleeding technique can definitely cause the stated problem. My opinion is that if you open the brake fluid system at any point on the pressure side, you must then correctly bleed it at EVERY point.
I would also try another mechanic, if this guy seems to be clueless.

My opinions are not intended to cause thread hijack debate.

sleeper

If you did total bleed out, & have ABS, I would think air is trapped in the ABS .. That can be time consuming to get it all out..

Did you use a pressure bleeder ?

pitbull76

Quick question: did this happen immediately after the brake work, or were the front pads and fluid changed to try and troubleshoot your problem? Or did it just start a couple weeks after the brake work?

seanomatic

Thanks a lot for the welcome and the replies guys. I just got back from a few days away in the mountains celebrating my 40th so I wasn't plugged in.

The culprit turned out to be a failed master cylinder which then proceeded to dump it's guts all over the electronic vacuum booster which caused that to fail (hence the pedal going to the floor after the engine was started). The new parts are in and the brakes works fine now.

My mechanic is clued in and as honest and ethical as they come - in a word "old school" (wish they all were like this guy!). He strongly urged me write a letter/phone GM in regards to potential design flaw as well as possible reimbursement (the warranty ran out at 36,000/the car has 65,000). He feels that mc should not be failing at this mileage and location of the mc inside of the booster is asking for trouble should the mc fail (ie catastrophic brake failure while doing 75 mph).

Any of you guys know if HHR's are prone to mc failure? I did a quick search of some other posts and found a few other people with mc failures.

donbrew

Evidently, they changed something since 2006! My 2008 LT has a vacuum booster with the MC mounted after it, just like every "old fashioned" car I've ever seen. Or, are you talking about the ABS module? I don't have one of those, so I got nothin'.

sleeper

Same on my 08 2LT, & my ABS unit is up near the radiator on drivers side

seanomatic

On mine the MC actually fits inside of the vacuum booster (not ABS module), perhaps Chevy became aware of the vulnerability of the vacuum booster failing due to leaked brake fluid. In any case I called GM customer support and they were very polite if not very helpful. Awaiting a return call on Monday.