spongebob Posted November 15 Report Posted November 15 i tried to use an o ring on the fill cap for the master cylinder on my 54 windsor. it does not seat properly and i actually ended up with a small piece of it broken off and ending up inside the master. the original one is a metal crush washer but i have not found one available anywhere. a teflon washer of this size would work, but where to get one? these small parts can often be hard to get. and as an aside, hidden valley auto parts is closing early next year. you can bring tools and get what you want. dennis Quote
soth122003 Posted November 15 Report Posted November 15 (edited) Are you sure it's a crush washer and not just a soft thin metal washer? If your just looking to seal it, try the hardware store for a washer in the plumping supplies. Or you can use thin cork gasket material and cut one your self. Joe Lee Edited November 15 by soth122003 Quote
Sniper Posted November 15 Report Posted November 15 McMaster-Carr or even Grainger are two places I go for stuff like that. Quote
desoto1939 Posted November 15 Report Posted November 15 (edited) I looked in my wagner brake catalog and looked up the master cylinder info for your car. You use the filler cap # FC4073 and the gasket is FC5922. refer to the picture 13c which is the filler cap and the gasket which is listed below it as FC522 Then go to picture 14 filler cap gasket FC5922 is listed as a fibre gasket 1 17/64 - 1 1/2 If you go to a Napa store with this information they might have it in stock or can order you one. This is again where having cross reference and old car manufacture catalogs comes in handy. On the last page go to the bottom of the sheet and look at FE17632 that is your master cylinder for your car Rich Hartung Desoto1939@aol.com Edited November 15 by desoto1939 1 Quote
spongebob Posted November 15 Author Report Posted November 15 desoto, alot of good info there. thanks. i have a napa nearby. i remember that the gasket was a thin metal washer, but having the correct fiber one should be better. thanks, dennis Quote
chrysleritis Posted November 16 Report Posted November 16 You don't need much of a tight seal on the fill cap on the master cylinder. The caps all have a small air vent hole in them, strategically placed so as not to let dirt in. So the gasket under the cap can really be any old thing as long as it does the job of keeping out crud. DIY cork or fiber should be fine, and I've had some janky-looking homemade gaskets on there over the years. Probably you're the only one who sees it! I prefer fiber, since it won't flake apart like a cork one might, which would land you back in the same place as with your piece of o-ring... 1 Quote
spongebob Posted November 19 Author Report Posted November 19 the reason i want a proper gasket is because i am losing brake fluid and cannot find a leak at any of the wheels or lines anywhere. while filling the master i saw that the oring i used as a gasket was ripped and a piece of it was inside the master. i think the fluid is coming out at the cap where the is no seal when you use the brakes. only way to confirm this is by having a proper seal on the fill cap. the fiber one is best since it will squish on and make up for the small amount of rust in that area. last time it went low it did allow some air in the system so now i have to bleed the whole thing. dennis Quote
bacelaw Posted November 19 Report Posted November 19 35 minutes ago, spongebob said: the reason i want a proper gasket is because i am losing brake fluid and cannot find a leak at any of the wheels or lines anywhere. while filling the master i saw that the oring i used as a gasket was ripped and a piece of it was inside the master. i think the fluid is coming out at the cap where the is no seal when you use the brakes. only way to confirm this is by having a proper seal on the fill cap. the fiber one is best since it will squish on and make up for the small amount of rust in that area. last time it went low it did allow some air in the system so now i have to bleed the whole thing. dennis You might be overfilling it. The book for my wagon says 1/2" *below* the top of the resevoir is the maximum. Quote
Bob Riding Posted November 19 Report Posted November 19 Moparpro makes a replacement cap Master Cylinder Fill Cap Might give him a call to see if he has or knows what would work. Quote
spongebob Posted December 2 Author Report Posted December 2 Bob, nice to hear from you, nice work on that master. my master was leaking from the fill cap, but i found a gasket for a carb. at the parts store that works, i will now search for the proper one. thanks for all who answered dennis. 1 Quote
Bob Riding Posted December 3 Report Posted December 3 Thanks, you too. I only hope it works as good as it looks! Quote
kencombs Posted December 3 Report Posted December 3 (edited) Sneaky leaks like that are sometimes hard to find. IME, the first place to look, after the obvious wheel cylinders, is the master push rod. Often leaks past the piston go no further than the dust boot. In good shape, that will contain the fluid so it isn't visible without pulling the boot back. Never have seen a master cap leak. And, if it did it should be obvious as the outside of the master would be wet below the cap. Edit to add: one of the good things about later firewall mounted pedals, leaks like that can't be seen, but can be smelled. A little brake fluid inside your car really reeks! Edited December 3 by kencombs Quote
desoto1939 Posted December 3 Report Posted December 3 I had a very small leak at one of my bleeder screws on my right rear brake. I found out that the taper on the end of the bleder screw was not the correct taper and that the fluid would then work its way out via the threads of the bleeder screw. I was able to find the correct bleeder screw and this solved my problem. saw a wet spot on the backer plate and had to look hard to find the issue but i found it. Take a look around the brake hose and also bleeder screw. Rich Hartung desoto1939@aol.com Quote
spongebob Posted December 4 Author Report Posted December 4 the fluid was definitely coming out the cap.put a temperory gasket on it.but, i still have to bleed the whole system. on the tech. site they recommendede a pressure bleeder so i may try that. dennis Quote
Sam Buchanan Posted December 4 Report Posted December 4 On 11/19/2024 at 8:58 AM, spongebob said: i think the fluid is coming out at the cap where the is no seal when you use the brakes. only way to confirm this is by having a proper seal on the fill cap. the fiber one is best since it will squish on and make up for the small amount of rust in that area. last time it went low it did allow some air in the system so now i have to bleed the whole thing. dennis The fluid reservoir is not pressurized when the brakes are applied. The gasket on the cap is to prevent fluid from seeping out due to the fluid sloshing in the reservoir. Also, the reservoir would have to run nearly dry before air would be introduced into the master cylinder. Having a good cap gasket is desirable but its failure doesn't explain the problems you are describing. Quote
Ivan_B Posted December 4 Report Posted December 4 On 12/3/2024 at 6:40 PM, kencombs said: Never have seen a master cap leak. And, if it did it should be obvious as the outside of the master would be wet below the cap. 54 minutes ago, Sam Buchanan said: The fluid reservoir is not pressurized when the brakes are applied. The gasket on the cap is to prevent fluid from seeping out due to the fluid sloshing in the reservoir. I concur with the above, something does not add-up. Try filling the master to specs, wipe it clean with alcohol or carb cleaner, and see what happens around the cap next time you notice the fluid loss. Quote
harmony Posted December 7 Report Posted December 7 Granted your car is a bit newer than my '48, so I don't know the routing of your brake lines but on my '48 there is a section of the brake line that is hidden, just forward of the master cylinder that feeds the front brakes. If there are hidden sections of brake line on your car it might be possible that there is a pin hole in the brake line due to corrosion in one of your brake lines. Quote
spongebob Posted December 9 Author Report Posted December 9 my neighbor has a lift i can use. i will get it up,and when the rear wheels turn i can adjust them since i cannot remember the last time they were done. then i will bleed the system thorughly. i did run the master dry the last time i was bleeding, so that put air in. i also read that the fronts need the lower cylinders bled first, then the uppers, and i only bled the uppers. not sure why that order. thenks for all the rteplies. dennis Quote
Ivan_B Posted December 10 Report Posted December 10 20 hours ago, spongebob said: I also read that the fronts need the lower cylinders bled first, then the uppers, and i only bled the uppers. not sure why that order. Oh, so you've got that fancy dual cylinder setup... 😅 Just do what ever it says in the manual. Also, you do not need a lift to do the brake adjustment. You can do do that just fine by using a jack, one wheel at a time. Quote
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