2007 Pontiac Torrent braking system problem
I have been having a mysterious problem with my 2007 Pontiac Torrent that apparently no one, not even GM, can diagnose.
Problem: After driving my car about 10 minutes, the brake pedal gets progressively stiffer and the car itself is “heavier” (no other way to describe it). If I continue driving, the car will begin to make a low roaring sound, which will get louder and louder if I continue driving. The car also at this point will lose acceleration and it is very difficult to make the car accelerate (that also makes the noise louder). A couple of times (luckily I was in my garage at home after driving), the car was stopped and when I tried to reverse, the car would not move at all.
When this problem first started (about 6 months ago), the Service Stabilitrak and Service Traction Control messages would come on, but I had a part replaced and that stopped (although the car was still having the same problem) until yesterday when those messages came on again. It has been four months since the messages stopped, yet the car was still having this problem during that time.
My remedy to this problem has been to pump the brakes each time I stop (I now take the highway instead of the interstate so that I can make enough stops to do this). I can go about 10 minutes before I have to stop, pump the brakes, and continue driving. This makes the stiffness in the brakes stop and keeps the car from making the noise and having the acceleration problems. The car runs fine as long as I do this.
During this six months, I have been to two different auto mechanics AND the local GMC dealer (at least four times). The parts that have been replaced are: right rear hub bearing assembly, EGR valve, rotors resurfaced, left rear caliper repaired, brake pressure modulator valve, and electronic brake control module. The dealership says they do not know what is causing this problem, and they claim they contacted the technicians at GM and they have never heard of this problem. Can I really be the only person in the entire world that has had this problem?
I feel this is a problem in the braking system. Something is getting hot the longer I drive and causing something to lock up the wheels, but not enough to stop the car entirely unless I continue driving. What stumps me is why does pumping the brakes help, and why are no service messages or warning lights coming on?
Any input or advice will be GREATLY appreciated! Thank you in advance!
I am a service advisor at a Chevy dealer in PA, I've had a customer in here (this would be his 5th time) with similar issues. 2007 Pontiac Torrent! First we found his brake fluid and pads low so we replaced those, and topped off the fluid. Came back in saying his pedal felt spongy-so we bled the brake lines. Next time in, we ended up replacing the master cylinder, and brake booster. today he says his brakes are locking up on him (again). My technician has spent multiple hours and hours on the phone with GM technical assistance trying to get this problem fixed for him. Our next step is to get on the phone with GM again, and a possible brake pressure modulator valve! Let me know if I can help with anything!
Do you have any update on this problem? The symptoms sound identical. So far I have a new master cylinder and new brake hoses. Plans are to replace the booster next, but wanted to see if the brake pressure modulator valve might be the problem instead? Anyway to diagnose which it might be?
I would add that once the problems start, if I put my foot behind the brake petal and pull up, they are relieved immediately. I used to pump the brakes, but using this technique is much more effective.
I went through it as well. for me It was the master cylinder. Upon getting the hubs, calipers, rotors and pads. Had an oil change. They again topped of all my "fluids" Once again my front end loaded up!
The master cylinder was dumping the break fluid into the booster.
So i got to the master cylinder easy enough. took off the masters 2 nuts and looked into the booster and sure enough break fluid! ended up siphoning out about 20 oz with a clear pc of 6 ft - 1/4 in tubing
was able to get it home to do the master cylinder change myself and spray down the booster with acetone and wiped it out and let it dry
i may have to do the booster in the future