Sunday, I decided to put new brake pads on my 79 280CE. Short version is that I couldn't get the caliper back on with the new pads in place and after squeezing the pistons as far in as they'd go to make room, and trying everything I could think of, I gave up and put the old pads back in (which hadn't quite hit the wear sensors yet) until I could figure what the problem was. Before you experts let me know how dumb I was, yes, I NOW know that pre-85 Benz used thinner pads, and while subsequent pads are the same shape, they are too thick...live and learn. After re-assembly, I surely got some air in the lines, as the brakes were now slightly mushy, so I "burped" the system from the top and added a small amount of fluid. This weekend planned to fully bleed the lines. Never made it. Driving home last night, I needed to slow and make a right turn. Foot pressure on the brake was about normal when suddenly, the pedal dropped almost to the floorboard and the brakes stopped working. I made the turn successfully, pumped the brake and got some resistance, and in the rear view mirror saw a huge, dense plume of white smoke come from the back of the car. What the?? At the next stop sign, brakes were very mushy and didn't work well. I nursed the car home, figuring I blew a line somewhere, and because it was sleeting, the underside of the car was too wet to pinpoint the problem. All night, I wondered...had I screwed up something? Did I blow a caliper seal, line or even the master cylinder? Where'd the smoke come from? Well, I waited until rush hour was over as the route to the local indy MB shop requires some highway travel, and since I had no brakes it was going to be an interesting trip. MB guy said: "caliper seal? We don't replace them anymore for liability reasons. Just put in new ones. And if you blew seals in the master cylinder...well (I think I could actually feel my wallet getting thinner the more he talked). I'll get to it tomorrow and call you with the diagnosis." Well, only 2 hours later he called: "drove your car inside and washed off all the brake fluid underneath. Saw that one of your brake rez' was empty, and the other full, and that you had a can of fluid on the seat. Used it to fill up. Pumped the brakes and guess what? (By now I'm having visions of a second house mortgage) The bleeder valve on the left front caliper was open slightly! You squirted brake fluid onto the engine causing the smoke. I bled the line, closed the valve and test drove the car. Your brakes are fine! You owe me $44 bucks." Whew. Dodged a bullet this time.
03-04-2004, 02:06 PM
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