The Stovebolt Site Forums The Shop Area General Truck Talk Bleeding Brakes

Tonight or tomorrow I'm gonna bleed the brakes on my 49 chev 1 ton. Got new master, front cylinders, rebuilt rear cylinders, all new lines, relined shoes. Just wondering if there were any "tricks" I should be aware of. As in; should I bench bleed the master? should I start at furthest wheel? closest wheel? doesn't matter? Do I need to have the bleeders open on cylinders to actually get the fluid to go all that way? Any advice would help.

I just did this on my 3600 a few days ago. The instructions with the master cylinder stated to DO NOT BENCH BLEED because you can actually push the rod in too far, said to do it on the truck so that the pedal will limit how far it goes in. So that's what i did, but not with the line hooked up, use a short piece of tubing or whatever you'd normally use when "bench bleeding". After I got the MC bled and filled, I did the RF first. I'm not sure if the 3800 lines run the same, but the trick is to do the wheel that is closest to the MC (meaning how far the fluid travels), and work your way out. Only open one bleeder at a time. I use one of those plastic cups with a rubber hose so brake fluid doesn't go all over and I bleed the brakes different that most people... I open the line first then have someone pump the pedal, then have them hold it when i don't see any more air in that plastic tube, then tighten the bleeder screw (I do this a couple times). Pretty easy that way, when you can actually see if there's air coming out or not. You'll have to fill the MC often. Adjust your brakes then bleed again.

Hey you oldcarandtrucknut,
Out of curiosity, what is the purpose of bleeding the master cylinder that way? as opposed to just trying to bleed it all at once?

The short tubing hooked up to the master goes into a separate reservoir just like bleeding wheel cylinders? After it's bled, do you have to switch out that temporary tube real quick with the permanent line before all the brake fluid runs out of the master cylinder?

I replaced all the brake parts on a '55 3100 last year, including the master cylinder, new steel brake line tubing, hoses, and wheel cylinders.

I found a little tool at my local auto parts store called a "one-man-bleeder" or something like that. I think it cost about $5. It was a little plasitic tube with a fitting at one end that fit over the bleeder valve on a wheel cylinder and a little check valve in the tube that allows flow in one direction only.

One end slips over the bleeder valve, and I put the other end into a clean plastic jar. Fill the master cylinder, open the bleeder valve and then gently pump the brake pedal.

Since I was doing this myself, I wasn't able to see the brake fluid coming out, I just pumped and refilled the master cylinder until I guessed was enough. The fluid that is captured in the jar is clean and reusable, so I'd just pour it back into the MC and go onto the next wheel cylinder. I started with a rear wheel cylinder that I thought was farthest from the MC. Worked fine.
LT

Because you'll have a greater chance of trapped air in the master if you don't bleed it first. Typical method is to bench bleed the master first. If the manufacturers directions say otherwise, then do that ( as in oldcarandtrucknut's case.) Most manufacturers say to bleed the farthest wheel first. As for the tube in the master, put the end of it into the resevoir, not a jar. Watch for bubbles there. After you bleed the master, don't worry about dripping fluid from the ports ( except to get it on painted surfaces.) Just don't let the resevoirs empty. The way I do it is bench bleed the master, leave the bleeder tubes on and bolt the unit into the vehicle. Then remove one tube and attach a line. Do the same with the next line. When I do these repairs out in the field ( I do this stuff for a living), I try not to bother other techinicians. So I usually gravity bleed everything. This might not be a luxury for you since the master is under the floor. So you'll need to grab a helper. The usual process is to have the helper pump up the pedal, then hold pressure. Crack the bleeder until the pedal goes all the way to the floor. Close the bleeder, release the pedal, apply pressure, crack the bleeder, repeat. Doing it one man is possible like others have mentioned with a tube and a clean jar. Best way is to pressure bleed but costs for the tools aren't justified for ocassional use.

If you are doing it by yourself, keep in mind that not much fluid is needed in the brake lines. So you won't need to use a complete container just for one wheel. It's a pretty small volume. Oh yeah, once you have a cylinder bled, tap it with a wrench or something. Crack that bleeder one more time and release any bubbles that might have been stuck to the cylinder walls.

F Booth, as i think i wrote before, the instructions said to bleed the mc that way to prevent damage. I wasn't clear about that short tube to temporarily hook up to the mc. One end should be fastened to the outlet of the mc, the other end should be put in the reservoir of the mc, completely submersed so air does not get back in when you let off the pedal. you could stick it in the bottle of brake fluid instead if that would be easier, just make certain it only sucks in brake fluid and not air when you release the pedal. After you bleed the mc, no, you do not have to put the actual line on super quick, it won't drip out from the mc.

A "trick" that I use is to adjust all of the brakes up tight so I'll know when I have all of the air out. Then I go back and properly adjust the brakes,
Scott