Cant bleed brakes 2008 Tahoe LS

[Coyotejunki]

just got back from getting the front wheels aligned. Decided to change out the brake fluid. Sucked out the old fluid from the MS with a syringe and filled with new fluid. Then went to front left wheel had to fight the bleeding screw, and replaced with a new one. Had my brother step on the brake then I would crack open the bleeding screw, close it, and then tell him to let up. I had a hose on the screw going to an empty bottle to catch old fluid. I maintained the level between low and full in the Master cylinder but just can't get the air bubbles to stop coming out when he steps on the brake and then I crack open the screw. I am frustrated.

 

[Coyotejunki]

OK, Update, I just tried again, but this time with the engine running. The brake fluid seems to come out a bit foamy, but not many large bubbles like before, and the pedals appears to be getting solid again. I realize the foam is air mixed with the fluid or at least I believe it. LOL I am just guessing but believe the ABS may be the reason. I haven't touched the other 3 wheels at all.

 

[Coyotejunki]

well maybe I just had a lot of air or starting the engine helped, IDK, but the brake pedals is nice and hard this morning.

 

[Geotrash]

Thanks for following up. Glad you got it sorted. For future reference and for others here, GM Tech2 scanners and equivalents have a procedure for bleeding the ABS system. It's a step that's not usually necessary for most routine work like replacing a caliper, but can be helpful when the pedal won't firm up.

 

[Joseph Garcia]

^^^^^x2^^^^^

Get yourself a quality bi-directional scanner to add to your tool box. Then, you will be able to read ALL codes, along with a brief explanation/pointer to the source of your issue. In this specific case, a quality bi-directional scanner can run an antilock device air purging routine that will take care of this issue quickly and efficiently. You will literally save thousands of dollars in diagnostic and repair costs over the life of your truck, and you will most likely recoup the cost of the scanner within 1 year.