I've got either the 4th or 5th master cylinder for my 65 Valiant with 9" manual drum brakes. I've tried remanufactured and new ones and each one of them leak from the same fitting on the bottom where there is a plug. I even tried wrapping it with teflon but nothing stops it. I'm currently running a reman Cardone master cylinder and I wrapped a coating of teflon on the threads of the plug and it still leaks. I'm using silicone fluid because the whole brake system was replaced and Right Stuff recommended it. My original one that didn't have an extra hole for a plug was sent to Cardone and deemed non-rebuildable and I was give one of their already reman units that is now leaking as soon as I put it on again from that same plug. The line to the top fitting is fine, no leaks at all. Just the bottom port where nothing goes it's just a plug. I remember someone telling me there was some kind of switch that went in that extra port for some kind of light. But I don't show it in my 65 Plymouth service guide. But here on EBAY I see one. What is that switch for? And here it's in the opposite hole. My line goes where that switch is in the picture. Maybe I need to get the switch and put it in. But what is it for? [ame="http://www.ebay.com/itm/1960-1966-Dodge-Plymouth-Manual-Break-Master-Cylinder-/201137848174?pt=Vintage_Car_Truck_Parts_Accessories&fits=Year%3A1965%7CModel%3AValiant&hash=item2ed4bfff6e&vxp=mtr#ht_226wt_1026"]1960 1966 Dodge Plymouth Manual Break Master Cylinder | eBay[/ame]
65 Valiant 4th or 5th master cylinder still leaking
- Thread starter wh23g3g
- Start date
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nm9stheham
Well-Known Member
That switch looks like an old style brake light switch, activated by pressure rather than one under the dash actived by the movement of the pedal lever. These may have 2 different ports types: one underneath for a brake line fitting and the other with a pipe thread or similar for the switch.
What are you plugging your 2nd port with? Have you looked into both ports with the line and the plug out? Are they both the type of port where brake lines will plug into, where there is an inverted flare at the bottom of the port? Or is one a tapered pipe thread or some other not-a-brake-line type of port?
I have had MC's where both ports were brake fitting types, and I had to take a brake line fitting and a short stub of brake line, weld the line shut, and use that to plug that extra port.
You can't plug a brake port line with a non-brake-line-fitting type of plug. It sounds like your plug is not right.
What are you plugging your 2nd port with? Have you looked into both ports with the line and the plug out? Are they both the type of port where brake lines will plug into, where there is an inverted flare at the bottom of the port? Or is one a tapered pipe thread or some other not-a-brake-line type of port?
I have had MC's where both ports were brake fitting types, and I had to take a brake line fitting and a short stub of brake line, weld the line shut, and use that to plug that extra port.
You can't plug a brake port line with a non-brake-line-fitting type of plug. It sounds like your plug is not right.
chryslerfat
Well-Known Member
The Ebay one almost looks like what I have seen on old farm trucks.
I called Dorman, Bendix, and Cardone. They all say each fitting hole is 1/4 NPT. I even tried buying a different 1/4 NPT plug to see if it would seal better. The hole where the brake line goes I guess is flared but when I look inside it has the flow valve cup or whatever it is with all the holes in it. The one that's leaking is just a bare casting with no flares just like and empty chamber type fitting. I'm getting tired of swapping them out going under the dash back and forth.
BillGrissom
Well-Known Member
I know what you talk about, and same deal for my 65 Newport. Most new MC's have the bottom port w/ a plug that you don't need. I had one MC with only the single horizontal port and it leaked because I over-tightened the "NPT to inverted flare" brass adapter and must have split the cast iron. Easy to do, so perhaps many rebuilt ones have a hairline crack. I fixed it with epoxy and maybe teflon tape, and used silicone. Don't know if glycol fluid would attack the epoxy. I since changed to a modern aluminum 2-port MC on all my 60's cars, which you might consider (read posts). If you were nearby, I would give you a new single-pot MC that came w/ a brake booster (if I didn't sell it, forgot).
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