2008 Trailblazer, messed up brake bleeding

Bled or attempted to bleed the brakes yesterday. I primary used a vacuum bleeder off my small compressor. So here is what I ran into and where I'm at.

Started at the right rear, no problems.
Left rear, got the bleeder partially open but ended up rounding it bad. Couldn't close it couldn't open it. Moved onto the left front.
Left front, snapped the bleeder off flush, it never budged.
Right front, no problems.
Still had breaking after that, but very soft and squeshy.

Removed the left rear caliper yesterday, replaced this morning with a remanufactured from O-Reillys. The left brake line was unconnected essentially overnight but I hung it to keep it from leaking. I wonder if I allowed a substantial amount of air into the system? Pedal goes to the floor, not getting any pressure it seems. I'm getting very little fluid to come out the new caliper bleeder, and the piston has not compressed against the pads.

Talked to O-Reilly, suggested I replace the front left caliper (with a broken off bleeder, but not leaking anything), and then rebleed everything. If that don't work, he suggested having it power bled which means I'll probably have to have that done for me.

I'm hoping this is just a bleeding issue and hope I didn't damage something.

I've learned my lesson about being easier on the bleeders in the future. Give PB Blaster more time to work, use heat if necessary and do not force the bleeder.

Any input or advice, I could really use it
I doubt anything in the system is actually damaged. you need to replace the broken parts and make sure all four corners are able to be bled out. then you need to do an "old school" bleed out where someone pumps the pedal and you release the air from the system. always start with the longest line in the truck and work your way to the shortest. which is not always the same in every vehicle.
And if after that if it's still mushy, you may need to get the ABS bled/flushed as well by the dealer or other shop that has a Tech 2 to cycle the ABS. Air may have also gotten into it too. And because the system was left open for a while, you should completely flush it rather than just bleeding it. Not a bad idea regardless.


Well-Known Member
If air got as far as the master cylinder, you might need to bench-bleed the master cylinder. (Not as bad as it sounds.)

But it is just likely you need to re-bleed the whole system once all the parts are replaced. Once you bleed the system, find a gravel road and lock up the wheels to get the ABS kicking in. This will bleed the ABS. Big Difference.

I also like a pressure bleeder rather than a vacuum bleeder. Vacuum bleeders can conceivably suck air in through the bleed screw threads.

At this point, don't panic and don't do anything until you get all the parts replaced. Then bleed the system again, kick in the ABS on a gravel road ... then come back and let us know how things are going.


Active Member
Thanks for the advice. The front left caliper should be in today or tomorrow, and I will install it tomorrow. So the two replacements I will have done are problem on the drivers side. I will bleed all four using a the regular bleed method, should I go back right, back left, front right, front left, considering my problem children were on both on the drivers side?
That is the standard method so you should stick with that. Basically the furthest to the closest to the master cylinder.
Good advice from everyone. Especially the ABS bleeding part by locking up the wheels. After a brake job on mine I went out on wet pavement and slammed the brakes on to cycle the ABS and it firmed the pedal right up.


Active Member
Update: Installed the second new caliper tonight (front left). Then did a two person bleed on all four wheels twice. The car is still up on jack stands wheels off.

The peddle is a lot better now but it does not remotely feel normal, there is still quite a bit of softness. When the ignition is off, there is a little peddle slack, then soft brake. With the ignition on, almost no slack but the peddle is softer than when the ignition is off.

Other notes: Two of calipers had pretty good flow coming out of the bleeders. The other two, it was a like a half second surge that cut way back fast. I also noticed that when the brake peddle is pressed, I can not turn by hand the two front wheels, but with a little effort I can turn the two back ones.

Do I have more bleeding to do? I left the car up and on stands in case you think I do.
Rears won't have the same amount of bite, that's normal.

Do the ABS bleed next. Good chance that will firm it up.

Get good clean fluid out of each caliper?


Well-Known Member
Not sure how you are bleeding the brakes, but all great advice so far so I will just throw this out.

With the engine off, master cylinder to the full mark, pump the brakes but make sure it's not bottoming out. Give the pedal 5 good pushes then hold, make sure the person pumping the brakes doesn't let up off the pedal until you tell them to.

Do this to the right rear, then left rear, right front, then left front. If one of the rear calipers has air, the other side won't fully compress, same with the front. You may need to go through the entire cycle a couple times. Use a clear tube into a container and watch for air bubbles coming from the bleeder.

Once you get a good bleed, the pedal should firm up pretty good.


Active Member
I have nice clean fluid coming out of the calipers, but like I said, some calipers are flowing better than others. But like I said, some calipers are flowing better than others.

I've actually done three methods of bleeding. 1) vacuum bleeder running on my 3 gallon air compressor (quickly depressurizes). 2) one person bleed with a bottle and clear tubing-a few pumps, open then close bleeder, tube in bottle in brake fluid to prevent air suck. 3) two person, 3 pumps and hold, open and close bleeder

My brother in law says when he has air issues, he uses his vacuum bleeder but rather than just sucking, he is also simultaneously pumping the brakes.

I will go back to bleeding, just haven't decided what method to fall back to.


Well-Known Member
Just curious, did you change the rotors? Sometimes a spongy or less responsive brake feel can be the result of not removing the greasy film from the new rotors with some brake cleaner.

I know one time I took about 4 feet of hose and attached to the bleeder screws and gravity bled with the hoses supported straight up but higher than the master cylinder. I think this was on a 1995 ish Chevy 1500 which had terrible brakes....had to try just about everything.


Active Member
No did not change the rotors. They look okay and before I bled the brakes, everything seemed good. Lots of thickness to the pads as well.

I've only been doing my own car maintenance for the last 6 months or so, and I started doing it, because I was tired of getting price hammered by some of the local shops and sometimes getting scammed as well.

Case in point with my TB and the brakes. Midas "supposedly" replaced the front rotors, calipers and pads two years and 8,000 miles ago. Price: $658. What I see when I'm looking at the brakes, they replaced the pads and one caliper, did not replace the rotors or the other front caliper. Shady work and while I'm on my soap box, each caliper was $138 in parts. Purchasing from O'Reilley's I most recently paid $53 and I think $68. This doesn't count them "replacing and billing" me for a new EGR valve on my wife's old Equinox, and what I recently found was a half ass weld job, no new EGR. Urhhh
Yep, lots of horror stories out there.

If after all that, the pedal is still spongy, you might have to bite the bullet and take it to a dealer to have it bled. I had to have that done once because air was trapped in the ABS.


Silver Supporter
Should still take it on a dirt road or wet road if you're brave and stomp the brakes. Get going 15-20mph (or quicker, whatever you're comfortable with) and stomp them. You'll hear and feel a pulsing in the brake pedal, do it a couple times then reassess the pedal feel.

I've done no brake bleeding myself but know from seeing here and personal experience that giving the ABS system a workout will firm up the pedal. Some jackwagon turned from the opposing lane across in front of me one day and I had to floor the brake pedal to keep from hitting him, ABS cycled and I stopped without hitting him. After I came off of the adrenaline rush I realized the pedal was much firmer and it's been that way for a month or so now.


Active Member
Thanks to all, brakes are fixed.

Used another 1/2 bottle (16 more oz) to bleed the brakes. I tried my Harbor Freight Pnuematic vacuum bleeder for a little bit, the one person and a bottle method for a little bit, but what ended up really getting the job done was the two person method. Even today I still had bubbles coming out of all the calipers. Finally the bubbles stopped and the brakes firmed up quite a bit. I ran a dirt road 3-4 times locking it up at around 30 mph, then on pavement locking them up at 55 mph, doing both of that really firmed up the brakes tight. I think everything is good now.

So DIY for about $130 I got two new calipers and a full brake flush. $70 would have been the cost if I had paid to have them flushed by the local Indy. So I did alright I guess and learned some stuff

thanks again


Well-Known Member
Curious why most use the gravel road method to engage the ABS, some buy a $170 scan tool to perform "auto bleed"?

Both methods will cycle the abs Motor.
Why not simply jump the ABS Motor at the relay?
I don't think you can at the relay. It's activated internally according to wheels sensor data or activation by scan tool.


Well-Known Member
^makes sense.
But at the ABS pump harness, should be able to feed 12v & activate pump. I still have a switch with 10' wire I used to bleed my '94 Jeep, made bleeding brakes an easy 1 man job using the pump to apply fluid pressure instead of pumping pedal. This would also help if any air gets into the master.
I'll look into this next weekend.


Nope. Again, it's internal to the ABS module. There's already +12V from the fuse, which is hot at all times. Ground is also always on.