The Stovebolt Site Forums The Parking Lot Big Bolts Another Brake Bleed Thread

I have a '54 6100 and I have read various brake bleeding threads as well as read the shop manual that I have. I can't get a stiff pedal. I have replaced the Master Cylinder, had White Post rebuild the Hydrovac, put on new wheel cylinders on the front. I can pump the brake about 3 times when driving to get a stiff pedal. I bought the truck in November and haven't been able to drive it, so I can't speak to how the pedal was before I bought it. Am I missing something that I am not reading or thinking of? Does it matter if the truck is running while bleeding or not.

I am bleeding the system manually. The only other thing that I can think of that I haven't tried...On the old master cylinder, there was a check valve and on the new one there isn't one.

Have you followed the Hydro-Vac brake adjustment procedure in the Shop Manual?

Do you have a Pressure Bleeder?

I had the same experience/problem, until I did it as described.

I don't have a pressure bleeder. Doing a 2 man brake bleed. We started at the hydrovac as the book says and went from there.

I do have a shop manual, but been using this procedure...Brake Bleedhttp://chevy.oldcarmanualproject.com/shop/1954truck/54ctsm0506.html

Did you adjust your brakes before beginning the bleeding?

Yes sir I did.

And you bench bled the m/c before installing?

First thing I did when I got it.

I'm sorry I'm no help. Sounds like you did they same thing I would do. Start with the hydrovac, go to each wheel (in the prescribed order) and then end with the hydrovac.

Well you are telling me something new. End with the hydrovac as well? I haven't read that part before.

That procedure (1.5 and 2 ton) is for use of a Pressure Bleeder.

Here is the procedure on a 1.5/2 ton with no pressure bleeder.

I posted that page as it showed the bleeding sequence. I used the manual bleeder page that you posted but it says refer to pressure bleeding for sequence. Did I miss something?

Nope, it looks like you followed the correct procedure.

I'll go back thru it again.

Well, I don't read it in that manual either. But I do remember reading it somewhere on this site several years ago, so that is what I do. Sorry for the confusion.

The brake shoe's need to be adjusted very close, I have my hydrovac bypassed for now and even with a decent load on the truck the brakes do a good job, good solid high peddle. I did not use a power bleeder.

On this page about Manual Bleeding, it says "on 1 1/2 and 2 Ton models, connect bleeder tube to hydrovac bleeder valve No. 1, Figure 59."

In this manual, I can't find Figure 59 or any Figure past Figure 51. Are there pages that are missing from this online manual?

My guess is that is a typographical error.''

Figure 9 (not, Figure 59)?

Figure 9 shows bleeding at the wheel cylinder

HydroVac bleeder valves (2, part number 24) are shown here.

Valve #1 and Valve #2 are shown here.

I apologize for misunderstanding your question.

You may have misunderstood my question. I have seen those diagrams that you listed and I understand those. What I am saying is that the manual that I reference speaks of Figure 59 but I have been thru the manual and I only see thru Figure 51. Are there any missing pages. If it is a typo on the Figure number, it's not figure 9.

Looks to be a mistake?

Most likely, #1 is the one labelled that way in the diagram?

I'm still following you on this kclark. Seems the manual has a misprint. In any case, I believe your procedure is correct: start the bleeding with the bleeder valve closest to the master cylinder (#1 on the hydrovac), and proceed the the next value (#2 on the hydrovac), and then to the next value (rear wheel cylinder). If you are getting all of the air out of your hydraulic system, you should have brakes. If you don't there's another issue. Keep us informed.

I am not sure which rear brakes you have BUT, on 55.2-59 2 Ton, you need to un-adjust the upper shoe on the rear brakes before you bleed. The top shoe on both sides needs to be all the way in (loosened away from the drum so it pushes the piston all the way into the wheel cylinder, to get all the air out).

http://chevy.oldcarmanualproject.com/shop/1955truck2/55ctsm0507.htm

I have a '54

Well, we went thru the system again staring at the #1 bleeder for the hydrovac. We still have to pump the brake to get a good pedal. The master cylinder we took off had a check valve. We are going to try that to see if it makes a difference for some reason. After that if it doesn't work, I just don't know what else to try.

There have been two comments about adjusting brakes, including one advising that the shoes need to be adjusted very close. I agree with this and would suggest that before you do anything else, try adjusting them so the wheels barely turn and see if you have a better pedal. This will only take you a few minutes and you can back them off if it doesn't work or seems too tight and might overheat. I have found the pedal responds to very close adjustment. Good luck,
Kent

I will try that the next time that I have time to bleed. If I pump up the brakes when driving (usually 3 pumps I have a great pedal) but then after a minute or so it goes to the floor again. I know that someone said the manual says to backoff on the shoes, but as I read it, that was using the pressure pump. Under manual, it goes step by step to get it started then refers back to steps 5-12 in the pressure bleeding but never refers to backing off the shoes.

Let me preface my response by stating that I’ve never owned a vehicle with hydrovac brakes. That being said, I have had good luck in the past with stubborn air pockets by gravity bleeding. Top off the MC with fluid and leave the top off. Open all bleeder valves and watch for fluid to start a regular drip. Let drip for awhile keeping the fluid topped off. As fluid begins a regular drip at the farthest point close that bleeder. Work your way farthest to closest closing the bleeder after it starts a good healthy drip. Do not let the MC run dry. Might work.🛠

kclark, my master cylinder did not/does not have a check valve, as far as I know it's the original style m.c. I rebuilt the master and all six wheel cylinders, all new rubber and steel lines, bypassed the hydrovac for now. Might I suggest you bypass your hydrovac and see if you get good peddle?

That does bring up a question. I have been bleeding with the cap still on the MC. Is it better to bleed without the cap on the MC?

I put the cap on but not tight, just to keep the fluid from burping out but let air in. I had no problem bleeding mine without a power bleeder and help from an inexperienced friend.

Well, The master cylinder that we bought isn't working quite right so you are using the piston and cup out of the new MC and put into the old one. The brakes are working much better. I get a stiff pedal that will stop on a dime but every so often I get a soft pedal that goes almost to the floor but the truck stops slowly. If I take my foot off and reapply the brakes it stops on a dime.

Sounds like the M.C. is still bypassing intermittently. can you explain a check valve in the system?

I can't explain the check valve. That's the way the truck came. But when I bought it, it hadn't been run in over a year. I bought it and had it towed.

I don't have to pump mine at all, you saw the load of hay on her, without the hydrovac in the system I had no problem with brakes. I had to back one rear off just a little as it was warmer then the rest but no grabbing, no fade, no pumping.

The pedal is stiff. Usually grabs after and a 2" push on the pedal. But as you said intermittently, it will be soft. If I leave my foot on the pedal, the truck comes to a slow stop, but if I let the pedal go and his it again, it is back to a stiff pedal and stops on a dime.

If your original M.C. is good enough I would get the correct kit for it and get rid of the check valve, or take the new one back and trade for another.

We have two types of pressure bleeders which give a solid pedal nearly all the time but back when we manually bled brakes I would plug the outlet (or both outlets on a dual mc) and step on pedal---shouldn't move AT ALL. Next plug off rear line(s), bleed front and check. If high pedal front OK. Repeat for back. If OK reconnect complete system and check. If only part pedal usually the mc doesn't have enough volume or wheel cylinders are too big. If in any check there is soft pedal there HAS to be air in that part of the system. With drum brakes there HAS to be residual pressure valve or the brake shoe springs will push all the fluid back to the mc and the first pedal stroke will have to move all the fluid back till the shoes contact brake drum. If the valve isn't incorporated into the mc brake line seat then a 10# inline valve is standard. Your system is all factory so exotic steps should not be necessary.

coilover, from what you are saying I take it that the original master cylinder in my truck has the residual pressure valve incorporated in the output port, spring loaded steel disc at the outlet. I see in the shop manual that is called a check valve, I was confused with kclark's set-up. Thank you.

Yep that is what I have.

We're going to bleed it again. The truck drives really good and has plenty of power for my trailer with my Kubota tractor. Just need to nail down these brakes and convert it to 12 volts for the electric trailer brakes and I'll be good to go.