I picked up a 1979 300SD with a little over 90k original miles on it. A friend of mine bought it from the original owners grandson, and I bought it from my friend. It obviously has sat for a lot of time, and the brakes were not in great shape. I was trying to get it driveable for my wedding back in March, but that ended up not happening.

When I got it the front brakes had no fluid. I added fluid and discovered a leak between the caliper halves on one side and they would start to stick/seize up when driving, so I replaced the calipers with good used units. Those started to stick as well, so I replaced the master cylinder and brake hoses to the front. They still stuck, so I replaced the good used calipers with another set of good used calipers. Those stuck also, so I replaced the calipers and rotors with the early w126 vented rotors and calipers, and new hoses again.

That is where I'm at now. I still have the front passenger side caliper sticking when I drive. If I pull over and crack the bleeder, I have fluid shoot out and it drives well for 10-15 miles. I'm afraid to to father than that. 4am the night before my wedding I thought I had it fixed but after a test drive I only got a brake overheat warning light, as pictured below.



I did notice that I have a rear brake hose weeping also, but that should not have any effect on the front brake sticking or seizing. I am nearing my wits end here, I can't imagine I've had 4 bad calipers. Is there a way for the hard lines to restrict fluid flow this way? Anyone else had to deal with this before? I wanted to make this car a nice reliable driver but I've never had this many issues with brakes before.

Thanks
Max

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Milan Brown 1979 240D, rebuilt OM617.952 turbo diesel, rebuilt 722.315 transmission - engine spun a rod bearing

1979 300SD, ~90k original miles, all stock