why would a drum wheel cylinder just leak?

[glsaved]

Speaking for any drums brakes, not just my contour.
So I found a puddle of brake fluid on the floor yesterday. Passenger side. Today I got around to removing the brake components on that wheel, and of course the brakes were this oily mess. Cleaned up everything best I could, and with the wheel cylinder itself, I removed the two pistons, cleaned up, inspected, and the seals were in perfect shape. Not stretched, torn, cracked, not hardened, etc. The brake fluid did seem kind of nasty though so I bled the hell out of that cylinder while replinishing fluid in the master. I need to do that with the other 3 wheels.

So everything cleaned up and back together, brakes work fine but whether or not they will leak remains to be seen.

Now having said that, why would they just leak like they did? It leaked during the night I guess cause when driving, the pedal was solid as it should be. No sponge, no sinking, etc. I will say the seapage was out of the pistons and not thru the cylinder body like if there was a crack.
While I am here, is it possible to remove the drum without having to remove the center axle nut? I finally had to pull the whole hub with drum to get it apart.

 

[gferr56]

The nasty looking brake fluid is caused from moisture in the fluid. Just the smallest speck of dirt, brake dust, or anything else on the piston seal will cause moisture to get into the line and then the breakdown of the seal starts. Cleaning it all up is good, but replacing the seals would be recommended. Cleaning it up may be good for a week, or a year, but it will start leaking again.

As far as getting the drums off... they've always been a PIA... They are especially hard when not up on a lift to put some more elbow grease behind them. I just recently did my rears too.. nearly an hour to remove each side. A very large screwdriver on each side an just keep wiggling until the shoes get under the lip on the drum. Once under the lip they'll wiggle off a lot easier.

 

[paulschott]

I replaced mine about a year ago. The nasty oil will corrode the cylinder and cause leaks. I Autozoned them and they were cheap I also changed out the rear shoes. Once they get hit with brake fluid they aren't worth squat. Don't fool with brakes to save a few bucks, new is the only way to go. Your brakes will leak again or just ooze fluid and drip on the shoes. A good panic stop will get you into the guard rail. Paul