[PontGuy]

Shiny I am right there with you, just a little earlier in the process, or maybe later depending on how you look at it..

Went to drive my '69 last March after it sat for a couple of months (mostly because the booster quit working.) No brakes. Opened the master cylinder and the rear was out of fluid, but the front disks should have been working. So I bought a booster and master cylinder from one of the local stores (Autozone?) and installed it. Tried to bleed the rears with the old "wife pushing the pedal" method but no air or fluid would come out. Then tried the fronts and found the bleeder broken off one of the calipers. Back to the store for a caliper. Put it on with a new hose and then tried to bleed the rears again without success. Pulled the rear wheels and found both sides soaked with brake fluid and everything rusted up. Pulled the feed line to the back brakes from the combo valve and plugged it thinking at least the front brakes will work. Then found the hose bayonet fitting was leaking on the new caliper, and I could not get it to seal.

So... I decided to replace everything on the brake system. And while I was at it, a new trunk floor, gas tank, susp bushings, engine, trans, exhaust, wheels, tail lights, wiring, chrome, emblems etc.

I finally have the "detailed" bay ready for the engine/trans- but before I drop it in I want to get the new brake system working. Everything is new including the brake lines and combo valve that I bought from inline tube. And I still can't get the rears to bleed right. I think maybe the master cylinder could be bad, or maybe the combo valve is sticking... but I am just getting started trying to figure it out. Oh, and now the hose fittings to the calipers won't quite seal all the way on both sides.

I don't want to hijack your post but maybe some info-sharing could help both of us!

Walt (Who needs brakes anyway..)

[Shiny]

Bob - Thank you for the good ideas. I am begging for things like you suggested that I have not tried yet. I will also follow the link, read the info, and order the catalog if necessary. I hope it answers my questions about the rod lengths.

Walt - Thank you too for taking the time to detail your experience. It cracked me up to hear how your brake repair got "just a little sidetracked". It does sound like your current situation may be very similar, so I would like to hear more about your efforts and results. There was another thread with a similarly frustrated poster (Jimbro727). We and others traded ideas for a while but he has not updated status:

http://forums.maxperformanceinc.com/...d.php?t=597593

You might want to check the switch on your combo valve to see if it is indicating a misbalance between front and rear. Inline Tube said this is a fairly common issue that can make it hard to bleed. Since your rears were leaking, this might be "tripped" on your valve. They said to check the switch both with and without pressing the pedal.

When you press your pedal, does it go almost to the floor then build up pressure on the front calipers? From your description, your rears may have air and I am curious if this will cause my symptoms or not.

Did you adjust your rear shoes to minimize travel? I'm not sure I did this right. What is the right procedure to adjust the rears with new shoes?

I did call Inline Tube again on Friday. The tech thought it possible that the master was "bypassing" as suggested by GStage1, but he could not tell me how to verify. He asked me to call again on Monday and ask their expert. He said they "have never had one returned for that", but "I suppose it could happen" ???? As it is my 2nd new one, I am not hot to go buy another without knowing it is the problem.

Also, GStage1 asked if all my new parts were "good"? How would I know this? I get fluid to all 4 when bleeding, nothing seems to be leaking and all 4 corners seem to be squeezing immediately after bleeding, so what else would tell me if they are "good" ???

I am a little suspicious about my rear cylinders. I replaced them about 3 years ago and don't remember where they came from. I finally got around to finishing the front conversion to discs this last winter, and all this grief started. I just don't see how a "bad" cylinder could apply pressure, not leak, yet cause the brakes to go away after a few cycles.

I am simply baffled by having the brakes seem OK after bleeding, then I go drive and after about 10 stops, they act full of air but there is no fluid leaking anywhere I can see.

I will post an update after I talk again with Inline Tube about both the master and the combo valve again.

[PontGuy]

I think our problems are similar, but not exactly the same- at least not yet. Sounds like you have fluid everywhere but have air in the system someplace. I suspect the master cylinder but its only a guess. Air can make the brakes feel fine at first but then go away after a few uses- don't know why its just my experience. Yes, my pedal feels like you described. Nothing at first until the fronts engage and then the pedal is still soft. Should be rock-hard but isn't.

I've replaced master cylinders, calipers, wheel cylinders on these old cars dozens of times, and changed rears so had to bleed the system out. But it has been a long time for me. This has been a comedy of errors but I am still confident I will get through it.

The combo valve has always been a bit of a mystery- I've always just ignored it and managed to get the system to bleed. But maybe not this time. My valve is now brand-new. To watch it you have to unscrew the electrical connector right?

One thing I plan to try is using the old lines to make a little loop and connect them to the master cylinder so that they discharge back into the top. Then cycle to make sure the rear is pumping. I will do this on the bench since it might get messy and figure it may at least help to make sure all of the air is bled out. The master cylinder is no. 1 suspect for me because everything else has been replaced but I am still having exactly the same problem getting fluid into the rear system.

I haven't tightened the rear adjusters yet. All the hardware and the wheel cylinders back there are new. But that won't help until I get some fluid at the bleeds. I don't see how a bad wheel cylinder could be causing your problem although the adjusters do need to be pretty tight to the drums for the pedal to be good. You can use a little screwdriver to tighten them up through the access holes in the backing plates- just don't go too far or the drums will drag. If the adjusters are worn out then they may not self-adjust by backing up.

Getting the hose connections to seal up to my calipers has been a real pain. Like I said, I've done this many times in the past, not sure why it is being so difficult this go-round.

Walt

[Shiny]

Yes, yours sounds different - no fluid to the rear at all?

I have a "one-man" vacuum bleeder that I use first, after replacing parts or breaking a line. It pulls a lot of fluid at the cylinder. It may help you make sure you have fluid all the way to the rears, and is cheap. I do not have the preferred "pressure bleeder", so I have been doing the "wife pushing the pedal" method too. The last time I "tried again", I got a few bubbles on the first two strokes, then 2 or 3 more with no bubbles, and moved to the next wheel. When I was done, I had decent pedal, but it doesn't last long.

If you know your brake warning light works, then give your car power, turn on the ignition, and watch for the warning light. If you aren't sure, or know it is not working, then just use an ohmeter or continuity light (easier to see from inside the car) between the switch and ground. I soldered long wires to a tail lamp bulb and ran from positive battery to lamp to combo switch so I could monitor while pushing the pedal. Mine never contacted, so I believe my problem is not a fundamental "imbalance", but yours may well be. If you see the switch contact, then the vacuum bleeder may get you going enough to correct the imbalance and "reset" the combo valve. I think you basically have to create an offsetting imbalance to reset the valve. For you, this would probably mean cracking both fronts and leaving them open while you bleed the rear and stop when you see the switch open up so you don't trip it the other direction.

My master was bench bled and then, when I started chasing my problem, I fabricated plugs for the front and rear outlets on the master. My master has bleed screws, so I put in the plugs, bled, and the pedal was literally solid. Inline Tube told me this means my master has been bled well and there is no air in it. I don't know if or how this relates to the "bypassing" comments, but I will be asking them later today.

Leaks at your calipers sounds frustrating. That is one problem I do not have! I have new hoses, banjo bolts, and copper washers... no issues. I did notice there were a lot of similar sized copper washers at the parts store, so maybe yours are not quite the right size ??

[PontGuy]

I am getting just a couple of bubbles at the rear and not very consistently at that. And no brake fluid. I checked the continuity through the valve with a meter just before shutting down the garage last night and it showed the switch was closed. So I need to see if I can get it to re-set, and then watch it as I try to bleed. I don't have a vacuum bleeder but I may pick one up since it looks like this may turn out to be some trouble.

I was thinking about your problem while driving to the office this morning- are you sure that the mechanical setup on the rears is not the problem? The shoes need to be pretty tight up against the drums or a bunch of the pedal will be taken up just moving them into position. I always tighten mine up through the back until I feel a little drag on the drum. How old is the hardware back there and what kind of shape is it in? Are your adjusters working OK and are you sure that you have the correct hand threads on both sides? I've actually seen adjusters installed on the wrong side, then they work backward and open up the gap instead of closing it.

If your master cylinder is "solid" when the ports are plugged then it does not sound like it is the cause of your problem. Mine is not as solid as would like when I bench bleed it, I get a little travel before it firms up even though I don't get any bubbles. Another reason that it is suspect.

Not sure why I am having trouble getting good seals to the calipers. Just re-installed with new bolts and matching copper washers last night. I think one side is finally OK, and the other is close. It may be the surface finish on the calipers. I never had so much trouble with this in the past.

Yes, my little "brake repair" got side-tracked. But restoring the car has been on my to-do list for a bunch of years. The fact that it was not drivable (or more correctly, "stop-able") finally motivated me to get started on it. After all its a lot easier to install a new brake system if everything has been pulled out and the chasis cleaned and painted first.

Walt

[bulletpruf]

Mike -

Man, this one sounds quite frustrating. Had the same problem on a 66 Chevelle SS396; finally gave up on it for a while and will attack it again at some point.

A few thoughts -

How old are your flexible brake lines? If they are old, one may be ballooning when you apply the brakes. I don't think this is the problem, but might be worthwhile to replace all 3 or at least have someone eyeball them when you apply the brakes.

Wheel cylinders are cheap and easy to replace or take apart. Same as above - I don't think this is your problem, but might as well rule it out.

I would try to gravity bleed, then bleed again a few times. I'm not so sure the vacuum bleeder is better than having the wife pump the pedal. Another thing to try is to run a rubber hose from the bleeder to a jar of brake fluid when you bleed the brakes. This way, you aren't sucking air back in the system.

Good luck,

Scott

[PontGuy]

Good progress for me tonight, and reading closely through all the posts was a big help. Thanks guys!

It seems that I have the dreaded "booster shaft is too long for the master cylinder" syndrome. I loosened up the master cylinder bolts and could actually see the plunger back off through the port holes in the rear reservoir as I did it. And now the rear brakes bleed just like they are supposed to. Since I bought the booster and master cylinder as a matched set, assembled in the box, I really shouldn't have this problem. Chalk another one up for the local parts suppliers.

My pedal is now rock hard without an engine to pull vacuum and the brakes are engaging at all 4 wheels. Hopefully I'll get the new engine installed and started up within the next few weeks. Then we will see if I still have a good pedal.

Getting all the fittings to seal completely has been an ongoing battle. I seem to be winning, but we will see what happens with vacuum on the booster.

Also, I am still getting a signal through the switch. With everything I've done I would have thought that it would have reset itself. Is there a way to force it back?

And I still need to resolve the cylinder fit to the booster. Is it worth pulling apart to see if it is adjustable? Or just throw in some flat washers and forget it?

Walt

[Shiny]

Walt - that is awesome !!!

As you probably saw from all my frustrated questions, I had been looking for answers on how to tell if that was my problem, but got no response. I was going to try washers but have not had time to work on the car this last couple weeks. I was not smart enough to pull the cover and look at the piston through the ports while loosening the nuts at the booster. Very clever !!!! You da man !!!

So how far did the piston move when you loosened the nuts? My memory is poor, but aren't those ports very small? Are you looking with the master full of fluid? I'm asking because I did loosen the nuts to check this once, but I was looking for the master to pull away from the booster (follow the nuts when loosened). It was not obvious to me, so I did not pursue, but I also suspect my hard lines to the master could be forcing it one way or the other so I did not trust this.

I attached the section from the manual that talks about this relationship. It says if there is a mismatch, then use a "service replacement adjustable rod". After all the work, washers seem like a bandaid, but where would an adjustable rod come from ??

Does anyone know if an adjustable rod is available, and if not, how to accurately gauge the rod penetration into the master? I was thinking some modeling clay stuffed in between the rod and the piston might indicate clearance, but I think an adjustable rod would be needed. I also still have no idea how much clearance is desireable, as the attached instructions simply show a gauge with no dimensions.

As far as resetting your switch, I was told to open both ports on one system to prevent pressure build-up, then press the pedal while watching for the switch to open. They did not say how to tell which direction the switch plunger was tripped, but from your description of leaky rears, I have to believe the front was getting pressure and the rear was not. I would suggest opening both rears while slowly pressing the pedal and monitor the switch. The idea is to get the plunger centered, then close up the rears.

I will definitely chase this, but according to the attached descriptions, if the port was "blocked" by an incorrect rod depth, the symptom would be brake drag, which I would personally kill for right now. Maybe the brake drag would happen with a factory master with check valves or something ? Anyway, I have nothing to lose by chasing this possibility so thank you for your success !!

And I will check my rear adjustment again. My rear axle has a new posi carrier so it is literally hard for me to rotate the drums while I am adjusting. If I tighten the shoes until I lock the drum, how many clicks should I back off ?? I will also double check the adjusters, but I think if they were backwards, the wheel would not be centered on the slot in the backing plate and it would be obvious ??


Scott -

Thank you too. All my parts are new with the exception of the front-to-rear hard line, a used booster, and rebuilt calipers. I was thinking the same about the rear cylinders. If I chase the rod length and it does not prove to be the source of all evil, I will probably buy new rear cylinders and try that. I have replaced everything else twice, so I guess if I want to keep being frustrated, this would fit right in !!

How do I "gravity bleed"? Does that mean simply open all the bleeders and let them drip into a jar? How long?


I am grateful for all the help and will beat this thing some day.

Mike

[Shiny]

Walt - woops, I meant open both fronts and push the pedal to try and center your switch because you want to create a differential pressure on the switch plunger that offsets the condition that tripped it.

[PontGuy]

Yes the ports are small but the new fluid is still crystal clear so its easy to see the piston move through them. Was looking down at it with my wife cycling the brakes slowly to see if any bubbles, and got the idea to back off the nuts to see if the piston would pull back any further. It didn't move much- maybe 1/16" or so? Nothing you would notice if you weren't looking for it. But that was all it took to make a big difference. I just left it "loose" and the system bled perfectly.

I wouldn't want to bet either way that this is your problem too, but worth a quick check.

I think there needs to be just enough clearance so that the piston is sure to pull back all the way. Too much might cause some chatter in the booster? Its the only downside that I can think of. I will probably check to see if mine can be adjusted somehow before going with the washers as a short-term fix. I bought the new booster and master cylinder in March, and I don't even remember which store it came from. And I really don't want to take the master cylinder back now that it seems to be bled and working properly!

It seems to me that the switch should center itself if both systems are working OK. But I haven't tried opening up both the bleeds on the front yet. Another follow-up task. I am going to keep on bleeding and checking for leaks every day or so for a while anyway.

I adjust the drums so that they turn by hand pretty easily but I can feel the shoes holding them back just a bit. Not sure how many clicks that takes. If you get both wheels off the ground then the posi won't be a problem checking this way.

The threads in the left side adjuster are opposite the threads in the right hand adjuster. If you install a left hand adjuster on the right side or vice-versa they will fit perfectly but work backwards. It may be an outside shot but I've seen it done before.

Walt

[ELKHORNAOG7]

If you get the catalog I told you about it will be in there about the pins and master cyl. some boosters use differnt pins and some have adjustable rods, if the plunger in the master cyl don't come back far enougth it can't full up with fluid when the brake peddle is rel.-----BOB

[bulletpruf]

Mike -

Gravity bleeding is just what you guessed it was - open the bleeders and let the fluid drip. Amount of time to drip is a good question; when I did it, I think I let them go for an hour or so, but not sure if this is long enough.

Good luck,

Scott

[Shiny]

Thanks again to all

Bob - I have tried to find info on the web site, but was not successful. I will call them tomorrow. I was looking for details and/or options on what they call adjustable booster pins, but probably missed it. They did, however, have a good troubleshooting guide online, and it said the spacing between the booster pin and master piston should be 1/64".

They also said that residual pressure in the rear drum system is necessary, and that it should be 10 pounds. They did not make it clear if an aftermarket combo valve provides this function or not. I am pretty sure my new master does not have a check valve in the rear outlet. The tech at Inline Tube said the valve should be integral to their combo valve, but I am skeptical given my earlier observation of rear cylinders seeming to be fully "returned" or "retracted" by the shoe spring tension. I will try to figure out how to verify this residual valve is either in my master or in my combo valve and is working.

Scott - Thanks for the gravity bleed thing. I will try it next time I get enough motivation to go after this again. Sounds easy.

Walt - The MPBrake web site linked below by Bob has a switch centering tool advertised on the home page ( I attached a copy of their ad). I would try resetting per my previous post, but if it doesn't work, maybe a call to these people and the tool could help?

They also have a tool to help bleed the master by "reversing" flow. It looks like a syringe is used to pump fluid backwards from the outlet port. If you are suspicious your master may not be completely air-free, this sounds like a potentially simple trick that could even be done in the car.

I will loosen my master from the booster and watch the piston. If I see any movement at all, I will put some washers in between and try it until I find a way to actually confirm and/or obtain the right pin spacing.

And I will check again on the adjusters. I would be so happy if I messed that up since I could see a path to the end of this rainbow. I am more than capable of putting them in wrong, and it would be very consistent with my symptoms, although after my pedal goes away, I can bleed them and get good pedal again. I did verify the shoes were at least keeping the drums from turning against my hand rotation. Do you think I could "unwind" the adjusters but have a good pedal after I bleed that goes away later? hmmmmmm....

[PontGuy]

I keep on reading about residual pressure at the rear drums too, but its something that I never was aware of. What I do remember (and observed when working with the rear brakes Mon night) is that they pistons remain extended after they are pushed out, but it is pretty easy to push the shoes together to press them back into the cylinders. And I believe that if you just let the brakes sit for a while- minutes? I think the spring pressure will gradually push them back in. Since my car is still on jack stands with no tires I can easily check this on mine and report back tonight.

I did glance at the site and saw the centering tool. Thought it was probably a tool to keep the valve from going off center during bleeding, not for centering it after it got out. But worth exploring. I checked continuity on my old valve and it is not activated even though the brakes were certainly not working before I removed it. This is consistent with my thoughts that the valve should center itself if the pressures on both sides are even. Of course it looks like hell, full of gunky brake fluid, and may just be locked up.

The adjusters are a long-shot but everything possible is worth checking. I had a good car buddy a long time ago that had big problems with the rear brakes on his Nova loosening up. I mentioned the left-hand/right-hand threads to him, and it turned out that he had them wrong. So I have seen this before, but not convinced your symptoms match up with his.

Walt

[Shiny]

Hey Walt,

I just got off the phone with tech at MP Brakes. I described my symptoms. His 1st thought was leaking rears. When I told him no fluid, even under the rubber things, he said "you are sucking air and need a residual pressure valve".

He said he did not know why, but occasionally, some of us are just "lucky". He said the valve holds 10 psi in the rear line, which is not enough to make the brakes drag, but is enough to prevent any chance of vacuum building in the rear system and pulling air in. He said it happens when the pedal retracts and there is suction on the rear line that builds faster than the shoes can retract to compensate. Makes sense to me and I am going to buy a valve.

I asked if the combo valve had the residual pressure valve built in and he said "NO!", it only had metering and proportioning functions. He said when I suck air into the rear line (probably through the rear cylinders), then the metering function is delayed since pressure is building too slowly in the rear system, which is why my fronts don't engage until almost to floor.

I asked him about the booster pin length and he said if it was too long, it was more likely to cause the brakes to drag and should not affect bleeding. If too short, it would simply cause weak brakes.... but would not lead to my symptoms. He does not sell an adjustable pin. He said if too long, best to grind, but shims would work. He said if too short, buy a long one and shorten it.

I asked him how to center your switch, he said open both front bleeders and apply pedal slowly until the switch opens. I think you are right about the tool. The cross-section I have of a combo valve would suggest the switch piston has a detent and the switch has a follower. If the piston had traveled enough to close the switch, you would not be able to reach the detent through the switch opening and push it back to center.

I am going to try and get my car back on the jackstands for the fifth time and check the adjusters again. I will look closely at the shoes and pins to the cylinder. I want to compare with yours so please let me know what you see.

Mike

[PontGuy]

Sounds like you had a good discussion.

I agree with him that it sounds like something wrong with the rears, but never considered a vacuum pulling in air. You would think that a wheel cylinder or fitting that allowed air in would leak fluid under pressure... but maybe not. Installing a residual valve certainly wouldn't hurt.

I forget what year your car is, but I am not sure that my 69 came with a residual valve. I actually blew through the ports in my old combo valve and they are wide open. And my new setup is exactly like the factory stuff that I pulled off- or at least looks like it is.

As for the booster rod, I can see that mine is too long. And fluid wouldn't get to the rears until I backed it off. Maybe if you start with a system full of fluid then it can cause the brakes to drag, but overall it inhibits fluid flow? One thing I learned long ago as a young engineer- sometimes things that are wrong can cause unexpected things to happen. But when you finally find what is wrong then fix it and move on. Anyway I still think that it is worth it for you to do a quick check, especially since it seems to be a pretty common issue.

Tonight I am going to rig up a light on the switch like you did so that it is easy to monitor, then try opening both bleeders on the front to see if I can get the valve to center. I will also take the drums off and see if the wheel cylinder pistons eventually return after being pushed out, and if so how long it takes.

Walt

[PontGuy]

Mike, here are the results-

My rear wheel cylinder pistons do return back under spring pressure when the brake pedal is released. Actually without the drums on, the shoes fall back against the backing plates and get stuck. But if I pull them away from the backing plates then the springs push the pistons in pretty quickly.

But.. I think I still have some air in the rear system. Not surprised, it will probably take more bleeding. And maybe that's why the valve doesn't want to return to center.

And I still have a leak at one of the calipers. It is close to sealing, but if I really stand on the pedal and hold it a while it starts dripping. I will pick up some new copper washers and try again tomorrow. Hopefully all the tube fittings are finally well seated.

And I double-checked my booster rod by tightening and loosening the nuts, and confirmed that it is about 1/16" too long. And it is not adjustable. So I installed some 3/32" thick washers and watched to make sure that I could not see the master cylinder piston move when I tightened it up. Looks like it will work fine this way.

Except bleeding and leak checking I don't think I am going to be able to do much more with the brakes without having vacuum on the booster. So I plan to go ahead and drop the engine in this weekend and concentrate on getting it set up and ready to break in.

Very interested to hear if your new valve fixes your problem since I might end up having to install one on my car.

Walt

[Shiny]

Thanks for the update. You are making good progress. I hope that leak figures out who is in charge soon.

Before I went to check my car, I placed a second call to Inline Tube. This time, they told me I must have a leaky fitting that allows air to come in, but no fluid out..?? Skeptical as I may be, I did tighten the fittings at the rear cylinders and at the flex tube.

When I asked about the residual pressure valve, they told me, "yes" it was built into the combo valve. If this was the Andy Griffith show, somebody would be pulling the bullet out of his pocket. They did not claim "master cylinder internal bypass" this time, though... So much for trying to get two suppliers to agree... So just for grins, I talked to a second tech at MP Brakes and he said he never heard of that valve being in an aftermarket combo valve but I could tell by poking a wire into the rear outlet port. If it has a valve, it will be right there. I plan to do this as I am not going to buy another part if it has no chance in helping.

So I jacked up the car and pulled a drum off. Please look at pics and tell me if you see anything wrong. I still see no fluid, and the adjusters are rotating the intended direction so it is not "self-loosening". I wiggled the pin between cylinder and shoe and it wiggles quite freely, which still makes me think there is a vacuum somehow being pulled that retracts the cylinders even farther than would naturally occur from the springs.

After the shoes retract, does the pin seem tight or loose on yours? I would expect the shoes to push against some resistance to get the fluid back out of the cylinders, and end up with the pins under some compression. Mine did not seem to be that way... felt more like the shoes had retracted against a stop, but the pistons in the cylinder had retracted even more.

I pulled the cover off the master and the 3rd pic gives another hint of something weird - the seal was "pulled away" from the lid. It is hard to see in my picture, but the right-hand "bellows" has expanded into the reservoir, which would be consistent with a vacuum somehow being pulled on the rear system. And no, I had not used my vacuum bleeder lately. Hints and allegations, but still no facts.

I then followed your lead and loosened the master cylinder mounting nuts while watching for movement inside the small port at the bottom of the rear reservoir. I pulled the master at least 3/8" from the booster, and saw nothing move inside the hole. I have no idea what it should look like, but nothing moved. I tightened and loosened, looked at both front and rear with a flashlight and never saw anything move. My conclusion is my rod is not too long, but I did not pull and measure. This is actually disappointing, as it was giving me some hope.

Next chance I get, I will pull the rear line from the combo valve and see if it has a residual pressure valve. If it does, then I am once more left with an empty idea box. If it does not, I have nothing to lose by installing the residual pressure valve.

Any other ideas?

Mike

[PontGuy]

Mike,

Your rear brake mechanicals look great. I have never checked to see how tight the pins/pistons are against the shoes after they are retracted, but the fit in your pics looks just fine to me.

But unless you didn't refill the master after the last time you bled the system, the seal being pulled into the master cylinder indicates that you definitely have a leak somewhere. If fluid goes out of the system when the brakes are applied, and then the pedal returns, the system will be under vacuum and pull the rubber boot in. And if fluid is getting out, then you can be pretty sure air is getting in through the same leak point. The bottom line is that the fluid level should never drop unless there is a leak. (The only exception is when the car has been driven long enough to put significant wear on the shoes/pads.)

I would clean up all the fittings on the rear brakes real good including the ones at both ends of the rear hose even though they are a real pain to get to. Then push the pedal in hard and hold it for a while. Do this several times, and check the fittings for any sign of brake fluid. (This is exactly what I have been doing the last several days, and finding that getting all the new tubing to seal up completely is a tedious job.)

The residual valve debate is interesting and has my attention, but I am not yet convinced that it is anything more than a smoke screen.

Walt

[Shiny]

You are right about not refilling after bleeding last - that will explain the cover seal protruding.

Next time I get a helper, I will do as you suggest and check for leaks with the system under pressure. That makes good sense. The most progress I have made to date was after repairing a leak I introduced by adding a flare union to extend the rear hard line so I could mount the combo valve up at the booster. I will look there again first.