Fleetwood Meadow Posted November 17, 2018 Share Posted November 17, 2018 I'm trying to get brakes in my '52 Cadillac and having a leak somewhere. There is no physical leak but I need to pump the brakes for about 5-10 seconds to get brakes. Then if I release the pedal I have to do it all over again. The master cylinder and wheel cylinders have been rebuilt. This system has a hydro-vac brake booster. When bleeding the system I used a vacuum bleeder connected to the first-in-line bleeder screw and I bled it for about 5 minutes. I got a tiny bit of fluid at the very beginning of the vacuum tube but that was it. Then it was all air. However the master cylinder never dropped its fluid level. What am I looking at as a problem here? Do I need to rebuild the master cylinder again or is this a symptom of a booster failure? I have never had the system working yet to know the competence of the booster. Link to comment Share on other sites More sharing options...
keiser31 Posted November 17, 2018 Share Posted November 17, 2018 (edited) Did you adjust the shoes prior to bleeding the brakes? If not, you may NEVER get a firm pedal or all of the air out of the lines. Adjust each brake shoe until you hear a slight rubbing on the drum when you turn it. Edited November 17, 2018 by keiser31 (see edit history) 1 Link to comment Share on other sites More sharing options...
PFitz Posted November 17, 2018 Share Posted November 17, 2018 (edited) If there is a check valve e in the master cylinder to retain slight pressure in the system to help the cylinder rubber cups seal and not weep fluid, it may not be holding that slight pressure. Paul Edited November 17, 2018 by PFitz (see edit history) Link to comment Share on other sites More sharing options...
Ben Bruce aka First Born Posted November 17, 2018 Share Posted November 17, 2018 I am with John. Sounds like adjustment needed. Ben Link to comment Share on other sites More sharing options...
Spinneyhill Posted November 18, 2018 Share Posted November 18, 2018 (edited) 3 hours ago, Fleet Meadow said: I used a vacuum bleeder connected to the first-in-line bleeder screw You might need to tell us what this means. The first cylinder to do is that furthest from the master cylinder, the last is the closest. Furthest and closest are relative to the length of brake pipe, not necessarily their physical location. For example, on my car, a big pipe goes from the MC on the RHS to the LHS to the splitter, then the RHS front wheel pipe comes back across, so the closest is actually the left front wheel. Put all the bleeding gear away until the brakes are properly adjusted, as stated above. Also, in 1950 3/4" pedal free play was specified; is that still the case in 1952? 3 hours ago, Fleet Meadow said: I got a tiny bit of fluid at the very beginning of the vacuum tube but that was it. Then it was all air. You mean a tiny bit of fluid came out of the cylinder, then just wet the tube and air flowed? Do you know the condition of the hydro-vac booster? Edited November 18, 2018 by Spinneyhill (see edit history) Link to comment Share on other sites More sharing options...
ArticiferTom Posted November 18, 2018 Share Posted November 18, 2018 Try bleeding with pressure . IE someone pressing pedal . Sounds like air leaking around cups . Also maybe because of bad flex hoses . Link to comment Share on other sites More sharing options...
c49er Posted November 18, 2018 Share Posted November 18, 2018 Pressure bleeding is the best way..^^^^^^^^^^ I've had the same issue's trying to vacumn bleed using 160 lbs air supply on a couple 50's cars with pro shop bleeders....didn't cut it...pressure bled them quick with a commercial pressure tank bleeder.. Both cars DOT 5 withframe mount brake boosters. Link to comment Share on other sites More sharing options...
Fleetwood Meadow Posted November 18, 2018 Author Share Posted November 18, 2018 According to the book you tighten the star wheel until the wheel can’t turn then back it of 14 notches. 14 seems like an awful high number but that’s how it is adjusted. The thought crossed my mind that maybe it was supposed to read as 4 notches but I did it how the book reads. Link to comment Share on other sites More sharing options...
Frank DuVal Posted November 18, 2018 Share Posted November 18, 2018 That's 14 notches of a fine tooth star wheel. Maybe a half a turn from locked up shoes? Not just dragging shoes, locked up solid shoes. I've had to wrap Teflon (PTFE) tape on bleeder screws to use a vacuum bleeder on poor fitting screws. Note, just wrap the threads, not the end of the bleeder that actually does the sealing of the brake fluid. You do not want to get tape into the brake system. You should get flow into the vacuum bleeder reservoir. If you cannot get an inch or so of fluid into the vacuum reservoir from the master cylinder, something is wrong. Should be able to get fluid to flow even with mis-adjusted shoes. You still will have no pedal until the shoes are adjusted to the drums. Link to comment Share on other sites More sharing options...
Rusty_OToole Posted November 18, 2018 Share Posted November 18, 2018 Sounds like the brakes were not completely bled and you have air in the system. I like to fit a clear plastic hose over the bleeder and loop it up a foot or so then into a catch jar. You can see the fluid and bubbles in the hose and know when nothing but fluid is coming out. 2 Link to comment Share on other sites More sharing options...
Frank DuVal Posted November 19, 2018 Share Posted November 19, 2018 The one man brake bleeder Rusty describes is in a lot of old shop manuals. It works! No loop needed, just with clear hose it gives a good visual of what is going on. Link to comment Share on other sites More sharing options...
54vicky Posted November 20, 2018 Share Posted November 20, 2018 did you bench bleed the master? if not you will turn blue in the face trying to bleed a wheel cylinders Link to comment Share on other sites More sharing options...
Fleetwood Meadow Posted November 21, 2018 Author Share Posted November 21, 2018 I decided to remove the hydrovac brake booster out of the car and opened it. The air side of the diaphragm had what smelled and looked like brake fluid soaked saw dust. I’m assuming that that is where I was sucking in air. I took the master cylinder off. Yes it had been bench bled before but since it was out again I rebuilt it and bench bled it again. It seems to be working great. When I took it off and cleaned it I looked in the bore and it was perfectly smooth. When I get it back in I will then bleed the cylinders. But for that I have to wait for someone to help me. These cylinders have interesting bleeding nipples. They don’t have the nipple for you to attach a line. They have a threaded section for you to screw in a nipple it seems. I’ve never seen that before so I am going to have to do the pedal pressing method. Link to comment Share on other sites More sharing options...
Bloo Posted November 22, 2018 Share Posted November 22, 2018 1 hour ago, Fleet Meadow said: These cylinders have interesting bleeding nipples. They don’t have the nipple for you to attach a line. They have a threaded section for you to screw in a nipple it seems. I’ve never seen that before so I am going to have to do the pedal pressing method. My 36 Pontiac has bleeders like that. They just have machine screws in them. I gathered it is just to keep the crud out (like the little rubber caps that go on more modern bleeder screws). I am fairly sure I bled them with a suck bleeder. I probably just crammed a hose over the outside flats. Link to comment Share on other sites More sharing options...
c49er Posted November 22, 2018 Share Posted November 22, 2018 For years and years on the old 40's 50's 60's cars I never bench bled the M/Cylinde. It was not even mentioned in the older cars shop manuals to first bench bleed the Master cylinder. I think the bench bleed the master cylinder procedure started as I recall in the middle 70's. I practically never had issue's bleeding the brakes. I usually would air burp the M/cyl using the pedal several times then start the proper pressure bleeding process. With a commercial pressure bleeder ( not a pump the spayer type DIY'er) it's very fast bleeding all the 70's and back old cars... even with frame mount boosters. I have both vacuum and pressure tank professional bleeders.... the pressure type is the best and fastet for the old cars. Link to comment Share on other sites More sharing options...
Dave Henderson Posted November 24, 2018 Share Posted November 24, 2018 (edited) For one-man bleeding, including if the bleeder nut is seized, pump up the brakes and push the pedal down with a stick braced against the seat. Crack the hose (or tubing at the rear) a partial turn open at the wheel cylinder or caliper, and close quickly. This may take doing several times. If the pressure isn't relieved by whatever amount you can make the turn then instead crack the upper end of the flex hose where it meets the rigid tubing. A bit messy but it has worked fine for me, have some old news papers underneath. Edited November 24, 2018 by Dave Henderson (see edit history) Link to comment Share on other sites More sharing options...
Spinneyhill Posted November 24, 2018 Share Posted November 24, 2018 (edited) I am with @c49er. Never bench bled a m/cyl. You can make a bleed nipple for those cylinders. Find a 1" long bolt of the correct thread and a short piece (1") of brake pipe. Put a double flare on one end of your brake pipe. Drill a little hole right through the bolt from head to toe. Drill in the bolt head a short length of hole large enough for the brake pipe as a push fit. Push the brake pipe in and solder it in. Now you have a bleed nipple. For one man bleeding, 1st adjust the brakes. 2nd, make sure all the bleed bolts are free. 3rd, find a tube to fit the nipple you just made and a jar or tin or something to catch the fluid. Now top up the m/cyl. Go to furthest wheel cylinder. Screw in your bleed nipple, tight. Attach tube, make sure the tube goes UP from the nipple before it goes down. Park the jar securely. Release the bleed bolt that contains your nipple. Now push down the pedal somewhat slowly. Again. I can get three pedal pushes per m/cyl top-up. Nip round and close the bleed bolt. Top up the m/cyl. Repeat. The upwards tube, properly sealed on the nipple, means no air gets in. If anything happens, fluid runs back into the cylinder, not air. A clear tube is helpful but you can't see it if you are not there! Just keep going until you get clean fluid. If the drain end is submerged no air will suck back up into the tube. Mine tube is a child's skipping "rope" cut in half - it happens to be a flexible plastic tube with a larger strong plastic "handle" that perfectly fits my bleed nipple. My 1930 Dodge Brothers has very good brakes for its era and I don't use any bleeding aids, like vacuum or pressure. When finished, wash down the brake backing plate and bleeding area and everywhere the fluid could have gone with soapy water. Edited November 24, 2018 by Spinneyhill (see edit history) Link to comment Share on other sites More sharing options...
Frank DuVal Posted November 25, 2018 Share Posted November 25, 2018 8 hours ago, Spinneyhill said: I am with @c49er. Never bench bled a m/cyl. ???😨 I can see you might say bench bleeding is not necessary, and get comments from those that like to do it, but NEVER? Thems strong words. I have put a lot of master cylinders on cars without need of bleeding the system because I bench bleed the master, bolt it in place without disturbing the lines and attach the lines carefully, leaving them loose. Have someone press the brake pedal as I tighten the lines. This is an important skill where salt is used and the bleed screws are FROZEN!😉 Not saying our antique cars should get this treatment, but it works if only the master is bad and everything else is up to snuff. Follow installation with a hard HARDER test to confirm. Bench bleeding came about with the dual maser cylinders and "not plumb" firewalls. When the master cylinder bore sits at a 45 ° angle to the ground, it is hard to get all the air out. Our rebuilt masters (parts found at US FLAPS*) usually come with either two plastic tubes and plastic adapters, or two plastic plugs. One method returns the fluid to the reservoir, the other method works the pistons against blocked outlets. Both methods want the same result, no air in the master before installing it. To do this, mount the master cylinder in a vise parallel to the ground. *Friendly Local Auto Parts Store Link to comment Share on other sites More sharing options...
Spinneyhill Posted November 25, 2018 Share Posted November 25, 2018 31 minutes ago, Frank DuVal said: Bench bleeding came about with the dual maser cylinders and "not plumb" firewalls. Well there you go. My firewalls are too old! The brake m/cyls are mounted horizontally in the chassis. I have bottom hinged pedals, not pendant pedals, which probably required sloping firewalls. And I have not ever bench bled a m/cyl. Haven't even thought of it. Wouldn't have known how or been aware you could. I haven't done brake work on anything with pendant pedals. We have no road salt and I haven't yet found a frozen bleed nipple. Our conditions are pretty benign compared to yours! Thanks for the heads up. Now I understand why you would want to do it! Link to comment Share on other sites More sharing options...
Frank DuVal Posted November 25, 2018 Share Posted November 25, 2018 I also just realized I mis-read your word, which is bled, past tense. I read it as bleed, a warning for others not to do it. That's the confusion I had. Of course you never bench bled a master cylinder, never had a problem, and that is great.👍 I read (past tense) it as a warning for others to not ever bleed a master cylinder, hence my "strong word" comment. Oops.... Probably not my last reading mistake!😉 Link to comment Share on other sites More sharing options...
Spinneyhill Posted November 25, 2018 Share Posted November 25, 2018 You misinterpreting what I said is my problem, not yours! My writing is not clear enough. I shouldn't use phrases. I promise to try harder. Link to comment Share on other sites More sharing options...
Fleetwood Meadow Posted November 28, 2018 Author Share Posted November 28, 2018 I have now bled the brakes. The master cylinder was bled as a just in case situation. The shoes had already been adjusted prior to bleeding. I get pedal pressure but I have to pump it once first. So it goes to the floor and then the second pump I have pedal pressure. I feel pressure in the pedal when it goes down to the floor as if it is in fact moving the shoes but they are too far for 1 stroke to apply them. I see nothing dripping or leaking and the brakes hold after I pump them twice. Link to comment Share on other sites More sharing options...
Spinneyhill Posted November 28, 2018 Share Posted November 28, 2018 16 minutes ago, Fleet Meadow said: the brakes hold after I pump them twice. Do you mean you get a stationary pedal, fairly hard, no matter how hard you push? If it is soft, there is still air in it. If it goes down slowly as you push, the master cylinder is leaking past. Anyway, it is still not right! Link to comment Share on other sites More sharing options...
Fleetwood Meadow Posted November 28, 2018 Author Share Posted November 28, 2018 When I push the pedal down the first time i feel slight resistance as if the brake shoes are being pushed out but not enough for the stroke of the pedal. I then release the pedal to the top of the stroke and push it down again. The pedal stops about 3/4 of the way down and is firm. If I release it and push it down again it holds firm at about 1/2 of the stroke. The pedal does not seem to slowly fall to the floor when holding in place. Link to comment Share on other sites More sharing options...
Spinneyhill Posted November 28, 2018 Share Posted November 28, 2018 It sounds like adjustment to me. Tell us how you did that. 2 Link to comment Share on other sites More sharing options...
Fleetwood Meadow Posted November 28, 2018 Author Share Posted November 28, 2018 How I did what? The bleeding? After I rebuilt the master cylinder I reconnected it. Instead of drawing the air from the line being open at the master cylinder through the entire system I vacuum bled the front left cylinder. Once fluid came out I went to the rear right, rear left, front right, and finally front left. If I get a firm pedal and back my foot off until just before the pedal is in resting position, wait for a couple seconds, then apply the brake I still have a firm pedal when I push it down. But if I fully remove my foot from the pedal I lose it and have to pump it twice again. Link to comment Share on other sites More sharing options...
Spinneyhill Posted November 28, 2018 Share Posted November 28, 2018 No, the adjustment? 1 Link to comment Share on other sites More sharing options...
JFranklin Posted November 28, 2018 Share Posted November 28, 2018 7 minutes ago, Spinneyhill said: No, the adjustment? The shoes only need to move a few thousandths of an inch to actuate stopping. Link to comment Share on other sites More sharing options...
Spinneyhill Posted November 28, 2018 Share Posted November 28, 2018 3 minutes ago, JFranklin said: The shoes only need to move a few thousandths of an inch to actuate stopping. Yes, if adjusted properly. I am asking for the method; there seems to be something wrong. The bleeding seems to be right so I think we can tick that off. Link to comment Share on other sites More sharing options...
MCHinson Posted November 28, 2018 Share Posted November 28, 2018 I once experienced some rear brake bleeder valves that were not sealing properly. After many attempt to bleed the system I removed the bleeder valves and replaced them with new bleeder valves and had no trouble with the brakes after bleeding them after installing the new bleeder valves. The original ones seemed to seal, but they were allowing air to be sucked into the system. It took me a few days to figure that one out. Link to comment Share on other sites More sharing options...
Spinneyhill Posted November 28, 2018 Share Posted November 28, 2018 Wouldn't they leak fluid when you put the brakes on? Link to comment Share on other sites More sharing options...
JFranklin Posted November 29, 2018 Share Posted November 29, 2018 (edited) 1 hour ago, Spinneyhill said: Wouldn't they leak fluid when you put the brakes on? I'm guessing the air molecule is smaller than the fluid. I agree the shoes need a couple thousandths clearance and all needs to be bled by the book, then go look for other causes. I couldn't get a good pedal on an old truck and found the drums had been turned so thin they were just flexing with the shoe. They looked plastic when I had the wife push the pedal while I watched the drums. Edited November 29, 2018 by JFranklin (see edit history) Link to comment Share on other sites More sharing options...
ArticiferTom Posted November 29, 2018 Share Posted November 29, 2018 (edited) Has someone maybe changed the wheel cylinders to the wrong diameter . Hence needing more fluid then can be provided with one push . Also make sure apportioning hole is open to let max amount of fluid back in M/C . Edited November 29, 2018 by ArticiferTom (see edit history) Link to comment Share on other sites More sharing options...
MCHinson Posted November 29, 2018 Share Posted November 29, 2018 3 hours ago, Spinneyhill said: Wouldn't they leak fluid when you put the brakes on? It would certainly seem like it would, but it did not. That is why it took several days to figure it out. Link to comment Share on other sites More sharing options...
Fleetwood Meadow Posted November 29, 2018 Author Share Posted November 29, 2018 I adjusted the shoes according to the shop manual. It says to tighten the star wheel until the wheels can not be turned. Then back off star wheel fourteen (14) notches. Link to comment Share on other sites More sharing options...
Spinneyhill Posted November 29, 2018 Share Posted November 29, 2018 (edited) Did you reassemble the shoes correctly when you put the rebuilt cylinders in? Short-lined shoe is the primary at each wheel, so the cylinder pushes it out to the wheel and the wheel pulls it further out. For a top mount cylinder, that is the front shoe. Did you do the major adjustment when you reassembled, before you did the minor adjustment you mentioned above? Did you first set the pedal free play to 3/4"? Edited November 29, 2018 by Spinneyhill (see edit history) Link to comment Share on other sites More sharing options...
Fleetwood Meadow Posted November 29, 2018 Author Share Posted November 29, 2018 (edited) I’ll check the free play again and make sure that is right. Upon looking at the manual again I’m thinking the locking anchor needs to be adjusted. That would explain the double pump to get enough fluid to apply the shoes. Any tips on how to do this the most effectively? I know it’s all straight forward but sometimes they have fun car tricks that make it easier and faster. Edited November 29, 2018 by Fleet Meadow (see edit history) Link to comment Share on other sites More sharing options...
Fleetwood Meadow Posted November 29, 2018 Author Share Posted November 29, 2018 On 11/28/2018 at 5:32 PM, MCHinson said: I once experienced some rear brake bleeder valves that were not sealing properly. After many attempt to bleed the system I removed the bleeder valves and replaced them with new bleeder valves and had no trouble with the brakes after bleeding them after installing the new bleeder valves. The original ones seemed to seal, but they were allowing air to be sucked into the system. My bleeders have a threaded flat surface at the end of them where the nipple should be. I’ve never seen it on a cylinder before. I attempted to use some “normal” bleeders on the cylinders but they were too big for the holes. Link to comment Share on other sites More sharing options...
Spinneyhill Posted November 30, 2018 Share Posted November 30, 2018 (edited) 1 hour ago, Fleet Meadow said: threaded flat surface at the end of them Might have had a wee bolt screwed in there to keep it clean, or something. See my post above on making a nipple. My Dodge 8 has that sort of cylinder. My resources end with 1950 so I can't give you any detailed information on 1952 models. Edited November 30, 2018 by Spinneyhill (see edit history) Link to comment Share on other sites More sharing options...
Frank DuVal Posted November 30, 2018 Share Posted November 30, 2018 (edited) Follow section b. Major Adjustment on page 9-2 of the shop manual. That covers the master cylinder push rod, the anchor pin and the shoes. http://cadillac.oldcarmanualproject.com/manuals/1952/1952 Shop Manual/09-Brakes/image2.html I'll include it here for others to follow along and comment if they have better ideas. A test for hydraulic vs adjustment issues of too much play is to tighten all four shoe adjusters until all 4 wheels no longer turn. The pedal should be rock hard and close to the top. If not, hydraulic issues. Edited November 30, 2018 by Frank DuVal added pages (see edit history) Link to comment Share on other sites More sharing options...
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