mike012997

Chevy equinox LT 2008

I initially was having problems with the brake fluid disappearing from the reservoir in the master cylinder (no idea were it was going ) but there was no leaks. Changed the brake pads on the rear because they were worn out and everything was fine and seems to solve the problem but now the brake pedal was too stiff and seemed to work at the least touch. Couple days later my wife was driving it and the brakes engaged while she was driving. She made it home and the service stabilitrak light was on. After sitting for a while the brakes released but the stabilitrak light is still on. I think i need to change the master cylinder, could this be the issue and could this make the service stabilitrak light to come on. Bleed one of the brakes, no bubbles but now there is a clicking noise near the gear shifter when i press the brake pedal. (In Florida)

Anybody have any insight ???

tech2

remove the bolts from the master cylinder to the brake booster. pull the master cylinder out far enough to see inside the booster. I'm wondering if the booster is filled with brake fluid.

mike012997

I pulled the master cylinder out before changing the pads but it was dry. No slush sound either. The service stabilitrak light would come on every two or three months, checked the reservoir it was low; light would turned off but no sign of leak in the garage.

ruley73

There is a correlation here. It is normal for the fluid level in the reservoir to decrease as the brake pads wear. You're not losing any fluid, more fluid is just staying in the calipers as the brake pads wear. Again, this is perfectly normal, when you compress the caliper pistons while replacing the brake pads, the fluid is pushed back up to the reservoir. New pads will make the brake pedal engage the brakes with less effort, and this should be expected.


Need more info about what happened here. One possibility is that one of the brake calipers may be hanging up. Make sure you lube up the guide pins with some high-temp brake grease whenever you replace the pads.


I think you're just hearing the shift-lock mechanism locking and unlocking - especially if the shifter is in Park . This feature is what locks the shifter in Park unless you are pressing the brake pedal.

mike012997

Reference my previous post about my brake problems on my 2008 chevy equinox. I realized my master cylinder was bad and was leaking brake fluid into the brake booster for about 6 months. The booster was full of fluid. I vacuumed it out with a wet vac, replaced the master cylinder, put everything back together and bleed everything out. I went to test drive it and got down the street and the brakes locked up again. I pulled the check valve out of the booster and the brakes released. The check valve seems to be working... it only allows aie to go through one way. I'm hoping the booster isn't bad (because they are expensive), or is there a way to take apart and clean the booster? I'm thinking there is still brake fluid in it somewhere.

Does anybody have any insight?

mike012997

Update
I went back and re checked the rear brakes, I checked the calipers and the slide pins for grease. they seemed fine but I put more grease on them anyways. Everything seems how it should be. If the check valve on the brake booster is bad would it cause the brakes to lock up after a while? My last resort it to replace the booster, but i'm hoping it is something else.

Has anyone had this problem?

ruley73

The check valve and brake booster would only affect the amount of assistance or boost that is applied when you press the brake pedal. If the booster is bad, it would require substantially more pressure on the brake pedal to stop or even slow your vehicle. I believe that your brakes locking up is a separate issue that is not related to the booster. If you live in the salt/rust belt, your front brake hoses could be bad and preventing the front brake calipers from releasing. Have you checked the front pads lately?

How does the brake pedal feel? Does it feel normal, spongy, or super firm as if the engine isn't running? If it feels normal, I'd replace the front brake hoses and see what happens. If it feels spongy, you may have air in the hydraulic system which needs to be bled out. If it is super firm then the booster is bad. To check for a bad booster, start the car and apply the brakes a few times, then kill the engine and push on the pedal a few times. Normally, the pedal should stiffen up after being pressed a few times after the boost from the booster is depleted (and not replenished because the engine is not running).

Also just FYI the correct order to bleed the brakes on the Equinox is 1) Right Rear 2) Left Front 3) Left Rear 4) Right Front

mike012997

At first the break pedal feels normal until it starts to lock up, then it gets stiffer and as soon as I touch the pedal; the brakes grab and then it really locks up.

I drove it around until it locked up. Made it home and took off all the tires. All four brakes were locking. The front left brake was locked up the most. I opened the bleeder valve on the front left brake and that brake released but the fluid didn't shoot out, it kind of came out slowly. I went to the front right side and did the same thing, and the same thing happened, it released and the fluid came out slowly it did not shoot out. I then went to the back tires and both the left and right side were freed up and i did not do anything to them.

If it is the brake hoses, How can they all go bad at the same time? And when i released the front how did the back release? I am really confused, i don't know what is wrong. Is it the hoses? Is it the booster? Please help!!!!!!

If it is the brake hoses that are bad, why is it when you pull the check valve out of the booster it releases the brakes. I have seen other people ask the same question but nobody has come up with an answer. I tested the booster and the brake pedal goes down when i start the car. I Checked the valve on the booster and it allows air to go through one way, but no the other way. So it seems to work fine. Nothing makes sense and i urgently need to get this up and running.

2008 Chevy Equinox LT FWD

FYI; I live in Florida (no salt)

mike012997

Update

I disconnected the booster check valve and I plugged it up. I ran the car for a while and pumping the brakes. It has not locked up yet. If the brake lines were bad or clogged, wouldn't it still lock up after a while? and if it doesn't lock up does that mean it is the booster that is bad? If I replace the booster in a 2008 equinox LT, how do i know which one. There are two first design and second design. First design is with out a BUSHING BETWEEN BRK PED PIN & BOOSTER PUSHROD. Second design W/BUSHING BETWEEN BRK PED PIN & BOOSTER PUSHROD.

208 Chevy Equinox LT 3.4L.V6

ruley73

Did you drive the car with the booster disconnected? I hope not. The hose being disconnected means the booster can't provide any brake assistance. This would make stopping a two-ton vehicle a tall order for anyone at anything more than 20 MPH or so. The catch is that since the booster is not functioning, there is substantially less pressure applied to the hydraulic system when you press the brake pedal. The reduced pressure means the issue of the bad front brake hoses causing the calipers to lock up will not not be observed.

I never said that all your hoses are going bad, just maybe the front ones. Each front brake hose has a mounting bracket that is crimped around the hose which rusts over time and squeezes the brake hose. This happens more often in the salt/rust belt and causes the calipers to lock up because the fluid is being forced through the resulting smaller passage in the hoses, but can't go back through it because there is no opposing force pushing on the fluid when you let up on the brake pedal.

As far as checking which booster you have, just pull the cover off under the dash and look at the connection between the brake pedal and the booster pushrod. Look to see if you have a "BUSHING BETWEEN BRK PED PIN & BOOSTER PUSHROD".

I guess that raises another question. Did the brakes work fine at any point between replacing the master cylinder and replacing the rear pads? In your first post it sounded like the brakes worked fine for a few days after the master cylinder was replaced. If this is the case, I doubt the booster is bad.

I'm still thinking the front hoses are to blame just because the symptoms seem to favor this and I know it is a common issue with the Vue/Equinox/Torrent; particularly in states where they apply salt to the roads in the winter.

A seasoned auto technician will need to chime in here, but I'm still not convinced that the booster is the problem. It might not hurt to get the codes scanned to see what DTC caused the SERVICE STABILITRAK message. The scanner will need to be able to read more than just powertrain (Pxxxx) codes in order for the code to be retrieved.