Brake flush procedure?

askibum02 · June 2, 2019

I'm getting ready to flush my brakes next weekend with a Motive pressure bleeder. Is there anything special I need to do with these particular trucks? My plan is to start with the furthest point and work my way around, i.e passenger rear, driver rear, passenger front, driver front. Do I need to worry about cycling the ABS or anything?

davester · June 2, 2019

If you have the regular/basic Motive pressure bleeder, it comes with a plastic cap that screws onto the brake reservoir. You don't want to exceed about 10-12 or so psi using it, as going higher, the cap may pop off, spraying corrosive brake fluid all around your engine bay. This happened to me when I tried to use the pressure specified in GM's full-service manual for my truck (IIRC, 25 psi).

The lower pressure works just fine, perhaps not quite as fast. If you really want to use a higher pressure, Motive sells a metal adapter cap, which stays on at higher pressures.

The main thing to be careful of, is for the reservoir on the truck to not get empty. If it does, everything you've done up to that point is wasted, and you have to start over with bleeding the master cylinder, then all 4 corners. If you are at all in doubt of having enough fluid to bleed a corner without the reservoir running dry, release the pressure, add more fluid, pump it up and then continue. It may take a couple minutes, but WAY less time than starting over.

The ABS system will retain a small amount of the old brake fluid. Because you haven't introduced air into the brake system, there is nothing special you need to do to bleed air out of the ABS system (unless, of course, you run the reservoir dry, in which case you should bleed the abs system as well).

If you want to get that last bit of old fluid out of the abs system, you can either use a computer (tech ii system, autogenuity w gm enhancement, or other system tools, which should/will have the procedure for doing it), or you can do it "redneck style", by bleeding all 4 corners as you decide (furthers from MC to nearest), then do a couple of panic stops on a gravel road to activate the abs system several times, then go back home and bleed all 4 corners again.

You may also want to spring for the little rubber caps for the bleed screws, as water tends to sit in them and then rust the screw to the brake assembly...

Nitrousbird · June 5, 2019

On 6/2/2019 at 3:48 AM, davester said:

If you have the regular/basic Motive pressure bleeder, it comes with a plastic cap that screws onto the brake reservoir. You don't want to exceed about 10-12 or so psi using it, as going higher, the cap may pop off, spraying corrosive brake fluid all around your engine bay. This happened to me when I tried to use the pressure specified in GM's full-service manual for my truck (IIRC, 25 psi).

The lower pressure works just fine, perhaps not quite as fast. If you really want to use a higher pressure, Motive sells a metal adapter cap, which stays on at higher pressures.

This. Motive bleeder is the way to go. Our German cars use DOT-4, which requires a change out every 2 years, so I do it frequently. Just used mine on my boat trailer as well. I will never, ever do the pump the brakes method again. This makes it quick and painless. I just replaced all the brake lines in my trailer last weekend and it took maybe 20 minutes (wheels on, boat on the trailer, so lots of sliding on my back) to get it fully bled. It would have taken 2 people a good hour+ to do it manually.