Brake / MC problems

I snipered this Prop Valve pic from Hellfish's thread on his brake problems. The pic of the MC an prop valve is from my 51' Chevy truck. I got drum brakes in the rear, and disk in the front. The chasis is an s-10. I have all new brake lines, cylinders (except new front calipers). New MC and prop valve.

I am am having a hell of a time getting fluid to the back mainly to the back brake hose. I can't even get fluid to there. I am getting fluid to a union about 3 or 4 ft from that (as it has leaked a little because the union wasn't tight enough). The MC is blead. I have tried bleeding that rear line forever and still nothing.

Upon reading another thread on here. I have to check my pushrod travel and play that I know. But I was just trying to double check that I have my lines plumed right with the Prop valve. Also on the MC is the reservoir closest to the firewall for the front brakes or back? I was told the front of the MC is the reservoir (toward the grille) runs the back lines.

At any rate, I believe I have everything plumed right. I have not tried bleeding the fronts yet. What I am told though seems contradicting to how I have my lines plumbed. Also the prop valve pic is identical to the one that I have hooked up on my system.

any help would be appreciated. Sum up. I have no fluid getting to any cylinders, atleast in the rear so far. My pedal is medium firm. So is that telling me the MC is working? It isn't like my clutch pedal when it wasn't blead, that thing was soft as a feather. But my brake pedal has some resistance to it.

thanks

 

These can be tricky at first. Is the check valve over centerd? Did you try bleeding the fronts yet?

 

Not sure what you mean by the check valve being over centered. I just
bolted it up to the stock bracket, it is offset from under the MC a little.

I did not try bleeding the fronts yet. I am definitely going to try that this weekend (as only time to work on the truck). I have to still check my push rod and make sure there is play and make sure the pedal isn't bottoming out
before the rod pushes the plunger to it's full potential.

Once I check that stuff, how long does it usually take to start getting fluid through the lines (they were all brand new)?? I am ***uming an hour or so?

I thought to hook up an electric vac*** pump to the lines, to **** the fluid through them, thought it would be quicker and more efficient. Obviously I would hold down the pedal during this process and make sure my MC stays filled. I have pumped these forever and nothing is coming past my second brake line union to the back. It is located at the end of my cab. Then there is a few feet before that lines connects to the rubber hose in the back.

I have also disconnected the rear line (before the hose that goes to the T) and put a clear rubber hose on it and submerged it in fluid. I can see fluid rise up and down in the hose that is in the bottle. So does that mean the MC is working and I just have a **** load of air in there? I would think I would see air bubbles coming up in my bottle, but there isn't.

Lastly, I am not noticing any air bubbles in the MC anymore. I was told you should see air bubbles in it and that I should re-bleed it. So I did that. Do my lines look right on my Prop Valve??

thanks

 

OK so you tell us the MC is bleed good . Is the porp valve all the way open ? That might be your problem with getting nothing to the rear . If it closed then you won't get a drop . If nothing still happens , then start with the MC and start working back st each connection to see where the problem is . Also usually the MC with the larger well is for the front disc brakes and the smaller on is the rear brakes . If the MC is equal on both side those are for drum/drum brakes . Disc/drum have 2 separate size wells .
I would check the prop valve first to make sure it's all the way opened up with no restriction . Just follow each connection and you will find out where the problem is . Now if you get fluid to your front disc brakes then it's the prop valve .
Sometimes they just like to be a pain in the **** .
Let us know what you come up with .

This is what I would do if it was mine ! Hope this helps !

Retro Jim

 

open the front bleeders pump the pedal a few times, then open all four bleeders and let it sit and drip. when they all drip steady close them and bleed like normal.

 

I do that with a MC . I just fill it up in a vice and place a drip pan under the MC . Then I go and remove the old one and get it ready for the new MC . Then by that time the MC has gravity bleed the MC by its self . I never had one not work and bleeding time was nothing .
I have also done that with brake systems as well but you have to keep the MC full ! Sure makes thing a lot easier . Of co**** if you have the one I had when I was a mechanic back in the 70's , I had one that held a gallon of brake fluid . The hooked it up to the top of the MC and put air in the brake tank . There was no problems ever bleeding brakes again . That was the damn best tool for brakes I ever had ! I think you can by cheaper ones now that do the same thing .

Retro Jim

 

try following my preceder it will center the proportioning valve and then gravity bleed it enough to allow you to bleed it

 

Thanks guys, when I bought the MC it said it was for Disc/drum. If I remember, it looks like it is the same size reservoir. I am going to check to see if fluid is coming out of the Prop Valve this weekend. My goal is to check the push rod first. Then check each line before the prop valve, then check the lines after the prop valve, then check cylinders.

I have not tried the fronts yet. Again, I am thinking of hooking up this vac*** pump to the lines and try ****ing the fluid out.

 

If I understand this correctly, you have rear pressure to the flexible rear hose but not at the rear cylinders. I'd be taking a real long look at that rear hose. I've had several that would deteriate inside to cause an interior "flap"....no pressure coming out the end of the hose. A simple hose replacement will fix it.

 

Rocky,

Ok, I have coming from my Prop valve going to the rear .25" line. I have two unions connecting the lines to the back. The second union is at the end of the cab. I have fluid there (because it has leaked there, before tightening). Then from that union it goes back to the connecting point which is the "hose fitting" The problem is, I have no fluid coming out of the line "before" the hose. So I can't determine if that hose or anything past that is bad. I disconnected the line from the hose, I then put a clear rubber hose on the line and submerged it in a clear bottle with fluid. Pumped the brakes, I can see fluid rising and lowering from the bottle, but no air bubbles coming up from the bottle. So the pedal is doing something, I am just not sure if maybe the plunger in the MC is fully extended or if there is just too much air back there. That is my main problem right now, I only know I have fluid to that second union in the rear, I haven't gotten fluid to any cylinders and again, haven't checked the fronts and or haven't even checked the fluid coming out of the Prop valve yet. I will be doing all that this weekend.

It just seems odd, I haven't gotten any fluid coming out of that line in the back, and I have pumped the piss out of it, but no fluid. I have become a little skeptical on if I had my lines crossed on my Proportioning valve.

 

Sounds like a bad rear soft hose....

 

Guys I appreciate the replies. But I have to emphasize again. There is no fluid getting to the hose. It is bone dry before the hose in the rear.

 

Lots of good advice so far. The valve you have has a saftey feature that will close off the cylinders with the least resistance. So if you are just bleeding the rear, the front will get air/hyd pressure and close the rear that your bleeding.
You should follow the advice of opening them all up, pump slow a couple of times to get it centered again sometimes. Plus the gravity bleed will get the fluid thier without having to pump sometimes. Then you can bleed it.
When you bleed these valves you have to do the fron and rear at the same time. So bleed the rear a couple of times and when you start getting a pedal bleed the front a couple of times untill you get a good pedal. Do it back and forth. Then give the system a solid bleed.
Hope that makes sence to you.

 

well, I just typed a whole bunch and couldn't post it.

So can I unscrew the lines running out of the prop valve and let it gravity
bleed? Maybe I got some air in there?

Would fluid running halfway back in the rear mean gravity did it or is the MC
doing something? Because I have fluid halfway back, just not far enough to
the hose link. I don't have fluid "before" the rubber hose in the rear.

Can I try the front and see if I can get fluid to them before I go nuts trying to get it to the back?

Once I establish all cylinders getting fluid, I can take normal bleeding procedures correct. Farthest from MC or should I go back to front front to back as you are mentioning (Hi).

thanks

 

What you have is a 3-way combination valve, and they really don't belong on vehicles they were not designed for. Sorry. I would pitch it and just use an adjustable prop valve with a 10 lb residual to the rears. Ok,.... at least maybe re-position the valve so the inlets are vertical, as bleeding might be a problem with the valve the way you have it mounted. All I've ever seen or worked on were mounted near vertical, and it might make a difference.

You do know you have to push that little rubber-covered ****on in to allow fluid to flow to the fronts with low (<100 psi) pressure bleeding? That's the metering or hold-off valve. Pretty hard to gravity bleed with these.

The proportioning valve to the rears is fixed and non-adjustable.

The middle switch is simply a pressure differential valve, and shuttles to one or the other system when a pressure differential of about 400 psi occurs. It does not shut off fluid to any brakes-it simply turns a dash mounted brake warning light on telling the driver you've got a problem! If you're not going to use the feature, it's just more **** that can go wrong, leak, etc.

You should contact the company you bought the master from to learn which port goes to the fronts, especially if this is designed for disc/drum. Most drum/drum or disc/disc masters are not 50/50 on piston stroke (displacement), even if the reservoirs look equal.

No reason why you can't bleed just one system at a time and get a hard pedal, although much nearer the floor. Like you pointed out, make sure the master pistons (full stroke) bottom before the pedal. The booster push rod is usually mounted solid to the pedal, but the master push rod should have 1/16" max clearance to the primary piston. This should be checked with full booster vacuum, but do all the bleeding with NO vacuum. (engine off, check valve pulled or vacuum bled down)

Good luck.

 

v8 bob,

Thanks for the insight. I planned on using the brake warning valve at some point. I'd
like to have a warning as to where all my pressure went.

I didn't know you have to push in that middle valve. So basically I need someone pushing that in and someone stomping on the pedal, with the bleeder valve opened right? I am ***uming that valve pushes in and releases on its own?

I will try and mount it vertically and also try contacting the company I bought it from. But I bought it off ebay, so I am sure it is a **** shoot if the company knows anything about their product.

Lastly, there was a rubber boot inside the booster with the push rod, should that be in there? Also I had to customize my own push rod to the brake, since they didn't provide me with one. So that might be causing some problems. Although, the pedal is not completely spongy, it actually has some medium resistance to it.

I should be seeing bubbles in my MC when I pump the pedal during bleeding right?

I appreciate your input.

 

I think an earlier guy nailed it about the valve being off center. I was a ch***is engineer at GM before retiring. When evacuating and filling a system, if under pressure there was a leak, the valve would shift as designed, isolating a specific component or line. If the valve was not re-centered, that part of the system remained isolated. Since we had to run an ***embly line, I made a tool to hold the valve centered under any condition. After the brakes were tested and OK, the tool was then removed. Usually you can feel the pin pushing out the little rubber cover on each end of the combo valve. Simply push the pin in to center the valve and try to re-bleed.

 

Saucerhead,

Great advise as are all of you guys. I will push that in and set it vertically if it will mount that way. I bought this set up from Fatrodder off of ebay, So I am going to hit them up and see what the deal is. Now this is obviously a dual MC since the reservoir is split? Just trying to eliminate variables and making sure they didn't send me a single and or a drum/drum MC. But even if they did, I don't see that being my problem as to getting fluid to the lines for a fresh bleed. That would effect things after it was blead correct?

 

Oh, one other thing that might effect this prop valve. When I first started bleeding the system, I didn't have one of the ports (for the front) plugged off (didn't even notice it). So I began trying to bleed the system and finally that port began leaking. So could that have offset the prop valve?

Again I have fluid in the rear all the way till about the end of the cab. So some fluid got back to the rear.

 

I am having the same on going problem.
Didn't even have to read your hole post and knew you weren't getting any pressure to rears. I will also bet you will have great pressure to the fronts when you try them for the first time after bleeding.
I disagree with some, keep the PV as 95% of the time they will work with most set ups. As far as I am concerned the adjustable rear PV can be thrown as far as you can chuck it if you are running one......................... JMO
please keep us posted.
Having fluid part way to rear dosen't mean you have pressure.......................

 

Well it is obvious some of you guys don't understand the internal workings of a dual MC !! ALWAYS bleed the chamber closest to the pushrod FIRST ,no matter which end of the car it is plumbed to. Flame suit on !!

 

Here's a simple tool that you can get from any brake specialty shop, it keeps the valve centered while bleeding............

 

I have several Motor Manuals that contradict each other on the bleeding procedure .......................... pretty confusing.

 

brigrat, word glad I aint the only victim here lol! anyway, yeah I'll try some things out this weekend. I will try the fronts and see how it goes. So the fluid that is in the rear line could simply be from gravity correct?

 

that would be my guess

 

No you are probably pushing some fluid but not building up enough pressure. At some point you may want to pull your wheels/tires & drums off and watch your wheel cylinders move, bet they move a little BUT with no real force or pressure. Warning though do one drum at a time so you don't blow out the wheel cylinder seals.................
This has been so frustrating that I have literally walked around the project for a month now not wanting to deal with it but time has come. My next move is to make sure that the push rod is moving far enough. Seems you can have a 6-7 to 1 ratio but that doesn't mean the rod is moving the distance it should...............

 

John,
It does not matter which chamber or system you bleed first, as long as the master can be bottomed out before the pedal, because the systems are completely separate. That's the whole purpose of a dual system, having each axle (in a typical vertical F/R system) operate hydraulically independent. It really is a good idea to bleed one axle, get a hard pedal, then open that system and bleed the other until a hard pedal results. This makes sure you will have brakes if one system fails, and proves your pedal/master setup is OK.

 

It's the front ****on you have to push in when low pressure bleeding, like when using a bladder bleeder, to overcome the 100 psi or so hold-off feature. Pedal bleeding produces enough pressure to open the valve, but push the pedal slow when bleeding, not stomping! That you do to pressure check the system once you have a good bleed.

Not sure about the rubber boot inside the booster?? A picture would help. Are you sure you are it's not the booster diaphragm? The master cylinder push rod is connected directly to it.

When you apply the pedal, you should see fluid bubbles generated from the piston cups closing off the compensating ports in the bottom of the master. If not, the pistons are not fully releasing

 

Ditto.
Get the centering tool. If you can't find it, it's pretty simple, you might be able to jury-rig it from an old switch.

 

V8 Bob : My 50 odd years of working on cars says otherwise. I HAVE corrected one than one no bleed problem by doing my way. Without the rear half being bled first the internial connection only moves the front piston about 25% of it's stroke. If your pedal travel will bottom out your MC soooner or later you may get things bled.