This was a new master cylinder installed about 5 years ago and has not had fluid added since. I clean the underside of the truck every winter and had not noticed this before now. From the picture, it would appear the fluid is escaping from the fill cap. I have not pulled the carpet to get to the access panel. Couple questions...is the cap vented? If not, is there an O ring or gasket on the cap? I suppose it could have been overfilled when installed, but it would surprise me. Any ideas on a failure, other than over filling, that would cause this? The truck is not driven a lot, mostly a trailer queen, but I have not noticed any issues with the brake operation. The entire brake system was new 5 years ago (maybe 100 miles of driving). BTW, the bottom half looks dry because I used a wire brush to start cleaning it to repaint.
Last edited by FallenHerosDad; 12/13/201711:29 PM.
Ray Charles could "see" the vent hole right there under the tab on the plastic cap. It's overfilled. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Also on my original master cylinder there was a fiber washer gasket on the cap.
Tim
I am currently digging back in to a 1953 3800 (one ton) with a nine foot bed. I've owned it since 1979, and drove it until 1982 (or so). My wife got me involved in restoring it back in 2002, got the body removed and the frame redone, then things came up. Now I am retired and starting again. If anyone is interested I have photos on Imagur ( https://timwhiteblues.imgur.com/ ). I live way back in the woods in the Ozarks on 40 acres at the end of a 2 1/2 mile private road.
Unfortunately, Ray Charles wasn't here to ask, but assuming it is over filled, How is the "Full" level indicated? I'm trying to figure out if I can correct this from underneath without pulling the carpet and access panel.
Dave, Routine maintenance requires checking the level of brake fluid in the master cylinder on a periodic basis. Even a trailer queen requires inspection, at least once a year, to be sure a leak has not occurred, dropping the level below the inlet port and producing a dangerous situation. Observing the fluid also indicates untoward corrosion or water in the fluid. I would respectfully suggest you change your carpet arrangement so that you can access the master cylinder through the floorboard as it was designed. You don't want to be guessing or hoping everything is OK.
There is no simple method to keep from overfilling. You want the level to be below the bottom of the cap, which has a built in baffle. Having said that it is difficult to gauge the level when the fluid is nice, clean and crystal clear. Personally, I wouldn't sweat that amount of seepage, especially after 5 years.
But I would sweat it if I hadn't seen the inside of my master cylinder for five years.
The rule of thumb has always been to keep the fluid level at least 1/2" below the level of the threads to allow for heat expansion of the fluid and/or splash from bumps, etc. Brake fluid is soluble in alcohol- - - - -use a spritz bottle to soak the outside of the casting and a bunch of clean rags to wipe it down. Use a turkey baster to suck up a little fluid if it's too full. If the cap doesn't have the fiber gasket it might be a good idea to buy or make one. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
