Meloyelo90 Posted September 25, 2008 Report Share Posted September 25, 2008 Very interesting (and scary) issue...a couple weeks ago I was on a steep decline sitting at a light, my foot was in the brake pedal pretty hard. After about a minute the pedal went almost to the floor and the Service Brake light came on. The light went off on a start / stop and ever since the brakes have felt very mushy. This past weekend it happened again in regular driving, so it's parked now for fear of getting in an accident. The truck still brakes but the pedal goes almost the the floor and it's very tough to stop. I was thinking of bleeding the entire system, (no leaks that I have seen), maybe some air got into the system when I sitting on the decline some how ? Replacing pads at the same time would probably be a good idea even though they look ok. Any suggestions as to what could have happened / how to troubleshoot ? I'm not a brake guy by any means. Thanks in advance ! Meloyelo Quote Link to comment Share on other sites More sharing options...
Fireman31 Posted September 25, 2008 Report Share Posted September 25, 2008 (edited) check your brake fluid level........sounds like a master cylinder problem...... Edited September 25, 2008 by Fireman31 (see edit history) Quote Link to comment Share on other sites More sharing options...
Meloyelo90 Posted September 26, 2008 Author Report Share Posted September 26, 2008 That was the first check - fluid was full. Very puzzling... Quote Link to comment Share on other sites More sharing options...
SSThunder Posted September 26, 2008 Report Share Posted September 26, 2008 you need to bleed the brakes because some where in your lines you've got some air bubles. It's possible your brake lid was not sealed and air got in when you were the decline. I had to service one of my calipers after replacing a wheel stud and the same thing happened to me. Brake light came on and pedal went to the floor. As soon as i bled the bake brakes all was fine. Make sure to top off the fluid during and after bleeding. Quote Link to comment Share on other sites More sharing options...
04CHASE Posted September 26, 2008 Report Share Posted September 26, 2008 could be air in the system but unlikly unless you have had your brake system open lately, are you low on brake fluid? the master cylinder could be a culprit but they are not common for going out, next thing i would see if your vacuum line to the brake booster/ pump are in good shape. Quote Link to comment Share on other sites More sharing options...
Krambo Posted September 26, 2008 Report Share Posted September 26, 2008 ... next thing i would see if your vacuum line to the brake booster/ pump are in good shape. That is where I would look. If you have a method to scan your fuel trims, you may be able to pinpoint an issue with vacuum going to the booster as well. Quote Link to comment Share on other sites More sharing options...
Meloyelo90 Posted September 26, 2008 Author Report Share Posted September 26, 2008 Thanks for all the replies. First thing will be to bleed this weekend, the more I think about it I am leaning towards air getting in from sitting on the decline somehow. Will also check the vacuum line to the brake booster. Keeping my fingers crossed...thanks. Quote Link to comment Share on other sites More sharing options...
benjaminh2 Posted September 26, 2008 Report Share Posted September 26, 2008 (edited) if the fluid is full, your truck would have to be standing on its nose to get air in the system. more than likely a vacum supply problem or a master cylinder as a couple other guys mentioned. check for brake fluid leaking from between the booster and master cylinder. Edited September 26, 2008 by gmperformanceguy (see edit history) Quote Link to comment Share on other sites More sharing options...
Meloyelo90 Posted September 29, 2008 Author Report Share Posted September 29, 2008 Well, I caved in and went to my local mechanic, mainly because I'm in the middle of working a fuel issue on my other car and just ran out of time. Long story short the rear pads / rotors were pretty shot so at first we were hoping a swap of those and then a bleed would take care of the problem. It did briefly... turns out there was a tiny pinhole leak coming from one of the brake lines as well. Very strange since there was no fluid on my driveway. Anyhow, bad portion of line replaced, new rears and back to normal. $270...wish I could have done it myself but the rotors were extremely rusted out and it would have taken me forever to find that leak. So why did the rears wear out so much quicker, and why the heck were the rear rotors completely rusted out when the fronts look new. Front pads are almost perfect. Could this be a proportioning valve issue ? I'm assuming we have these on our SS's. Thanks again for all the assistance. Quote Link to comment Share on other sites More sharing options...
Fireman31 Posted September 29, 2008 Report Share Posted September 29, 2008 (edited) So why did the rears wear out so much quicker, and why the heck were the rear rotors completely rusted out when the fronts look new. Front pads are almost perfect. Could this be a proportioning valve issue ? I'm assuming we have these on our SS's. Thanks again for all the assistance. It's common on the AWD SSS for the rear brakes to wear out before the fronts AFAIK. GM had a problem over the last 5-7 years with rotor rot on factory rotors, that is why yours looked like crap. How many miles are on your truck? Are the front brakes original or have they been replaced before? Edited September 29, 2008 by Fireman31 (see edit history) Quote Link to comment Share on other sites More sharing options...
Meloyelo90 Posted September 29, 2008 Author Report Share Posted September 29, 2008 Interesting...72k miles on the truck, fronts look brand new but have never been touched unless they were done prior to the 10k mark when I bought it (doubtful). Thanks for the info. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.