The Stovebolt Site Forums The Shop Area Driveline Bleeding brakes

I replaced the master cyliner, all 4 wheel cylinders, and the 2 front rubber brake lines. The brake pedal will go to the floor when I first push it but will build pressure if i pump the brake a few times. I have tried bleeding the brakes a few times without luck and i am not losing brake fluid anywhere. I have never bled brake lines before, am i doing it wrong or is there something else? Thanks Steve

To help we need to know every time you start a new thread exactly what truck you are working on. What procedure are you using to bleed the brakes? Yes there is a “Right” way to do it. We will walk you through it once we know what you are working on.

Steve, I reviewed your other thread about the drums binding up, and you said that you had to file off the wheel cylinders to get the drums freed up. Is it possible that you put the cylinders on upside down? That would cause a problem with bleeding as the bleeder screws wouldn't be at the top of the cylinder. Just a thought.

What Martin said about telling us what you're working on. If you only have one truck, put that info in your signature in your profile (click your username in the upper right and chose "edit profile" then scroll down that page till you get to signature and put the info there.) It will appear in all your posts.

Thanks for the feedback. I have a 1949 Chevy 3600. The bleed screw is on the top. Our technique has been my wife pumping the brake pedal several times and then holding pressure while I open the bleed screw for a few seconds. I am not seeing any air bubbles. I bled in the order listed in the manual - driver side rear, driver front, passenger rear, passenger front. I have read other posts saying to do the rear wheels first, but decided to follow the manual. I appreciate any input.

I assume that you adjusted the brakes as described in the '49 shop manual before trying to bleed the system. If there is too much clearance between the shoes and drum the pistons will move to the end of their travel without any air or fluid coming out the bleeder.

I did adjust them prior to bleeding them. I do get brake fluif out when I bleed them

Once you get some pedal after a few pumps, does it feel firm, or is the pedal "spongy"? If there is air trapped somewhere in the system, it will compress as pressure is applied, giving the brake pedal an uncertain feel and poor braking of the vehicle. If the shoes are simply out of adjustment, after pumping the pedal enough to displace fluid and get the shoes firmly against the drums, the pedal will feel solid. The fix for these two problems is different. Try adjusting the brake shoes until it's difficult to turn the wheels- - - -not locked up, but enough that it takes some effort to turn each wheel. Then try the pedal. If it's firm, with little if any travel, you've found the problem. If the pedal still requires a few pumps to keep from going to the floor, there's still some air trapped somewhere.
Jerry

It is the second - firm not spongy. I will try adjusting the shoes. Thank you.

Adjusting Huck brakes can be a frustrating chore. Each shoe has its own adjustment, so you're going to repeat the process 8 times before you're done. I believe the procedure is to tighten the shoe firmly against the drum, and then back off until the wheel turns freely, but don't overdo it. A low or no pedal situation when there's not any air in the system means that the full stroke of the master cylinder is being used up just to get the shoes into contact with the drums. As long as even one shoe has room to move, none of the otherws will apply any force to the drums. The closer you can get the shoes toi the drums without creating a constant drag situation, the more pedal height you'll have. It's a constant balancing act between pedal travel and not making the brakes drag. Huck brakes also have to "wear-in" until there's full contact between the linings and the drums, so you might have to do repeated adjustments after getting the brakes relined.
Jerry