mystereons

Hi all, really hoping you guys can help because now my car doesn’t have proper brakes and the truck needs a new axle seal, so kind of in a bad situation. I just replaced the whole brake booster assembly and I am having the worst time figuring out how to bleed the brakes. I’m
following the instructions in the attached. I did Step 2, which is bleed the brake booster, and it turned off after 10 seconds like it was supposed to. Now I’ve moved onto Step 3, which is bleeding the brake lines. The instructions say to put the ignition in the “on” position. Is it normal when you depress the brake pedal (just before the bleeder screw is opened), for the brake booster pump to run?? Right now even with all bleeder screws closed, I can’t press the brakes without the pump coming on. The pump is pretty loud. I bought it used on eBay, and wondering if the pump is bad or just has air in it? How often does it normally run in the normal operation of the car? Because I don’t remember hearing anything that loud normally. Secondly, while I’m holding the pedal down and the other person opens the bleed screw, periodically the ABS/TRAC/VSC comes on while the pump is running and there’s a long beep and it sounds like some other mechanical thing is coming on. Anyone know what that is?? I’m not sure what I’m doing wrong or if the things that are happening are normal. Please help!!!

mystereons

Ok so after doing some reading, it seems like the front brakes are supposed to be bled the traditional way by pumping the brake pedal, and the rear you just hold down the brake pedal, open the valve, and let the booster pump do the work for you. The rear brakes seem to be bleeding normally. The pump comes on and a lot of fluid comes out. The issue is with the front. The booster pump comes on when bleeding the front, which I thought wasn’t supposed to happen. Is that normal? Also, very little fluid is coming out either side of the front. When the front bleeder valves are opened, the pedal slowly falls to the floor. Is that normal? Am I supposed to follow the pedal to the floor? That’s what I’ve been doing but worried it could damage the master cylinder?

mystereons

So this is the sound I hear with the ignition in the on position and I press the brake pedal. Is this a messed up pump or maybe it just has air in it?

IanB2

Rear brakes are bled using the pump to push fluid through until it runs clear, make sure it doesn't suck the reservoir down too far and suck air in, it moves fluid pretty quickly. Front brakes are bled the traditional way. The pump will run anytime the brake pedal is pressed, as that's the only way the rear brakes work. If the pump is noisy it's possible it's got air that needs to be bled out, or it may just be a noisy rebuilt pump? The video is pretty noisy though, hopefully it quiets down after being bled.

With having the system opened up like this, you may need to drive it to a gravel road and do a few ABS activated panic stops and then bring it back home and bleed it all again to get the air out of the system.

mystereons

Hi, thanks so much for your response! We’re having more luck bleeding the front brakes using one of those hand vacuum pumps. We also cracked the bleed valve open more than we were originally. There’s a ton of tiny bubbles. When the liquid comes through the tube, should it fill the tube completely, or is it normal for it to only be half full? We’ve already gone though about a half gallon of brake fluid doing the front brakes. Still a good amount of small bubbles and it never completely fills the tube. On the bright side, the pump only runs for about 1-2 seconds with the ignition on and only turns on every other time the brake pedal is pressed. It also seems quieter. So I guess we’ll just keep doing what we’re doing and hope it improves further! If anyone knows about whether the tube should be filled completely, let me know.

mystereons

Oh I also forgot to say, I got a Innova CarScan Tech that claims it does ABS Bleeding. So I’m curious if it will bleed the ABS solenoid. I was testing it out and it sounded like it was maybe actuating the solenoid, but I’m not 100% sure that’s what it’s actually doing. Here’s are some screen shots. It did a 4 second test, and there were about 4 separate clicks that maybe came from the solenoid.

IanB2

You don't really need the key to be in the ignition for bleeding the front brakes, as they don't rely on the pump. That scanner is likely cycling the ABS block as it claims, and it might work to get all the air out of the system. I've found for stubborn air locks, an actual ABS panic stop can dislodge things better than a controlled cycling of the system, lol.

The length of the hose plays a pretty major part in answering your other question, but as long as it's pushing fluid/air out when you crack the bleeder, the process is working. Make sure you're going from furthest to closest from the master cylinder, and not letting the fluid level drop so it sucks air in.

mystereons

Thanks for letting me know about the fluid level in the tube.

I’ll keep the panic stop in mind if the scanner doesn’t work out