gpspfish

I have a 2007 Equinox and have recently noticed that the brake pedal is quite spongy. It does eventually stop the car but the pedal is about 1inch from the floorboard. I carried it to the local dealer and after testing was told that it was the master cylinder loosing vacuum. The master cylinder was replaced but the problem still remains. The dealer does not seem to have any idea what else to do to correct the issue. If this problem cannot be resolved the Equinox will have to go. It is an LT version with AWD. It has about 121,000 miles.

morbid81

When you remove the master cylinder you open up the braking system, you probably air in the system, take it back and have them bleed the air out of the system if they didn't to see if that remedies your issue.

ruley73

Not likely because the ABS actuators can be used to bleed the system with the GM scan tool. I doubt a dealership would waste their time doing it the old fashioned way. With that said if they didn't first bleed the lines as they were reconnecting them to the master cylinder this procedure won't work either.

morbid81

They need to do it the old fashion way, that is why the brake pedal goes to the floor you have air in the system. Tell them to bleed it through the bleeder valves on the caliper starting at the passenger side rear and going to the driver side rear, then front passenger side and over to the driver side. You gotta do all 4 now the system has been opened up and exposed to air.

ruley73

It seems I misread the service manual excerpt I got my info from. The procedure to use the ABS actuators to bleed the lines is not intended an alternative to bleeding the lines manually. It is only suggested if the pedal is spongy after pressure-bleeding the hydraulic lines to remove any air that may have been trapped in the brake pressure modulator valve (BPMV). Also, most newer vehicles have a specific order in which the hydraulic lines must be bled. You can't just go in order of farthest to closest to the brake master cylinder as you mentioned.

The correct order for the Equinox as specified in the factory service manual is

1) right rear
2) front left
3) rear left
4) front right

tech2

easy way to tell if there is air in the system is to: while driving during a brake application, repeatedly pump the brake pedal. this will send more fluid into the lines compressing the air. if the pedal seems to be not so deep or comes up after the accumulated pumping and holding the pedal on the last pump; there is air in the system. releasing the pedal completely will allow the air to expand and the pedal will be spongy again.


if they didn't fix the problem, return and speak to the service manager.

Droberts

The brakes in my 2010 Chevy equinox LTZ 4 cylinder (96k miles) were very spongy. I replaced the brake master cylinder yesterday and bled the brakes. Then I took it out for a test drive and it did exactly the same thing as before. I had to push the brake pedal all the way to the floor to make it stop. After reading a couple of blogs online, one suggestion was to take it out and slam the brakes down several times. I thought it sounded extremely foolish but I said what the heck, might as well give it a try. I started at 10 mph and slammed the brakes, then 20 mph slammed the brakes down, then 30 then 40 then 50. I repeated the process one more time just for good measure and it because it was kind of fun.
What do you freakin know? The problem has been solved! Apparently the ABS had to be recycled or reset, I'm not sure what that even means. But the problem has been fixed!!!

morbid81

one other thing is did they bench bleed the master before putting it on? that brake bleeding procedure is the same as my 90 bonneville the two wheels are on one chamber hence the cross bleeding then. Makes perfect sense guess GM seems to keep old habits alive in some of their vehicles.

tech2

as previously mentioned
after bench bleeding the master cylinder, manual bleeding the lines, abs pump bleeding is required to remove air from the abs pump. if you don't have access to a scan tool, creating an abs activation is a clever way to go about it.