83 240 D
After I c-clamped the pistons back as far as possible, I still couldnt wedge the driver side caliper with the new pads on it back on the rotor that easily. (Curiously enough, the passenger side caliper went on easily)

The brake rotor is running hot and grabs and pulsates, I dont think its warped yet, because I've only had it one day on the road and havent hit any puddles.

I'd like to fix this. Is the rotor still good? I'll sand the pad down if necessary.

Pads
 

Be really sure that you have positioned the pad in properly, maybe use a hammer to lightly tap it in place then try. Careful about sanding or grinding it down, the brake dust is supposed to be harmful esp. if it has asbestos

If the wheel will turn, there isn't much interference and a little sanding of the pad should solve the problem. If there is an unworn ring on the outside edge of the rotor, sand or grind it off.Have you tried to switch the pads? One might be a little thicker than another.

If the rotor doesn't cause the brake pedal to pulsate, the rotor is OK. Just think how hot the rotors get when you stop quickly from 100 MPH. They are made to take a lot of heat without damage.

P E H

How often have you bled those calipers? MB braking systems love fresh fluid, and if they don't get it can tend to stick a bit. I also don't use a c-clamp, a large and small screwdriver combo works much better.

I don't know if I am ever going to replace the pads an my '80 300SD. I have about 115,000 on the car since I bought it in '90 (227,000 total) and it still has the same pads in it. They look less than half worn out now. I make a lot of long trips where brakes might not get used for 100 miles or more and I downshift on some hills..

P E H

Its still a good idea to bleed the fluid with regularity. Time also effects brake fluid, over time even without heavy braking, the fluid absorbs a great deal of moisture, lowering the boiling point and contaminating the fluid. .

Jason M.

If the brake hoses are pretty old (10 years or so) it may be you have an internally failed hose. Deteriorated rubber in the hose can act as a check valve holding the piston out. You can push the piston back manually, but when you apply the brake, the pad stays against the rotor, dragging and creating lots of heat. Check that this is not happening by applying the brake, then trying to spin the wheel by hand with the wheel off the ground.

Also, sometimes a little bit of rust in a critical spot can prevent the pads from seating properly.

Just a couple of things to check...good luck with it.