My low brake pad warning light came on a couple days ago, which surprised me, since I put these OE pads in a year ago. Popped off the wheel and sure enough, they're very low (not urgent low, but they need to go) ... I also noticed the rotors drag. They dragged lightly when I put them in, but seemed to stop after a couple hundred miles. I have not had any problems with braking performance AT ALL with this car, and my mileage has been great (right in line with average). I could probably just throw new pads in and go, but I'd like to address or explain why the pads drag and why they wore out after 15,000 miles. Most of it was around-town driving so it was reasonably rough on brakes, but even then ... isn't that low? It strikes me as odd that they would wear prematurely, yet I never heard or felt a dragging, nor did my mileage suffer.
Since the dragging occurs on both front wheels, is it more likely an MC problem than a caliper issue? Last time I checked the calipers moved in freely but with quite a bit of effort.
I'm kinda bummed because this car is my daily driver and I don't want it out of commission ... but it looks like I'm going to have to swap it with the 240d in the garage. Too cold to do this work outside.
AND ... here's something else I noticed when I had the wheels off. Don't now why I didn't notice this before. Is it just me or are the dust caps NOT supposed to look as though King Kong went postal on them?

Obviously the last person to do the brakes on this car replaced the dust caps using a sledge or something, and it really ticks me off. I had the brakes done (new rotors and pads) about four years ago at a shop I don't live anywhere near and haven't used since. I had already noticed a rear bleed screw had been broken off, assumedly by the same shop. It's not the end of the world; the brakes perform great. But it goes to show how careless some people can be. Makes me wonder what else I need to be worried about.

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1987 300D, arctic white/palomino--314,000 miles
1978 240D 4-speed, Euro Delivery, light ivory/bamboo--370,000 miles
2005 Jeep Liberty CRD Limited, light khaki/slate--140,000 miles
2018 Chevy Cruze diesel, 6-speed manual, satin steel metallic/kalahari--19,000 miles
1982 Peugeot 505 diesel, 4-speed manual, blue/blue, 130,000 miles
1995 S320, black/parchment--34,000 miles (Dad's car)

All rotors drag. There is no mechanism for retracting the pads. When you release the brake pedal, the pads have no force against them and they just ride lightly on the face of the disc.

If you can rotate the rotor with your hand (which you can because you determined that they "drag"), the system is functioning properly.

Just pull the pads and replace them............clean the slides on the caliper and add a touch of grease to the sides of the pads.

Some gorilla smacked the grease cap on............instead of tapping around the flange to seat it. Naturally, it lost squareness with the hub............so he hit it harder. The cap should never be hit on the center of its face..........only along lightly along the flange via the use of a a hammer and large screwdriver.

Thanks BC. These seem to have a stronger drag than my 240D, but maybe it's just due to the different caliper design. They do turn, as you said, so I guess all is OK. That's what I'd thought when I first changed them and they dragged, but the quick wear of these pads had me re-thinking. Maybe I'm just underestimating how much harder, city driving I do now as compared to the last set I went through.
I'm going to replace the dust caps on principle. I can't imagine why a professional shop would think it's OK to hammer them on like that. When I did the 240D's wheel bearings, I replaced the dust cap with a punch lightly tapping around the flange ... not so difficult. One more good reason to do things myself.

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1987 300D, arctic white/palomino--314,000 miles
1978 240D 4-speed, Euro Delivery, light ivory/bamboo--370,000 miles
2005 Jeep Liberty CRD Limited, light khaki/slate--140,000 miles
2018 Chevy Cruze diesel, 6-speed manual, satin steel metallic/kalahari--19,000 miles
1982 Peugeot 505 diesel, 4-speed manual, blue/blue, 130,000 miles
1995 S320, black/parchment--34,000 miles (Dad's car)

I can.

That's why most of us will never go to a "professional shop". In fact, the term "professional shop" is a bit of an oxymoron in many cases. The only thing professional about most of these people is the strict definition of the term............they get paid to damage your vehicle.

You brake hoses could be showing their age- They should be replaced every 5-6 years, most aren't done until they split and leave you with no brakes. As they age, the rubber flakes inside, and can block return flow. If your brake fluid is dark, that is rubber "dust" floating in it, and the fluid should be changed.
As far as retracting, all disk brake systems actually have two mechanisms inherent in their design that retract the pads: First, the piston seal. This is a square cut rubber seal that flexes slightly when the piston moves. The sealing face against the bore doesn't move as far as the piston does, and it pulls the piston back a little. The second is rotor or bearing runout. There will be about .0005-.001" of runout in a rotor after the very first heat cycle, and about .001-.002" play in properly adjusted bearings at the outer edge of the rotor. These combined will help push the piston back in.
There will be a little bit of drag, but make sure it's the pads and not excessively tight bearings. Without the pads on, you should get a solid two turns out of the rotor/hub assembly when you give it a spin. A very slight amount of play, but not loose, and zero play with tight bearings that only allow 3/4turn or less is very bad.

Bodhi, you can also install the dust caps with a properly sized socket used improperly in conjunction with a hammer (gently of course).

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Hanno
'79 6.9 Sold (after 27 years)
'83 280SL, 5 spd.
'94 E320 Sdn. 5 spd conversion
'02 E320 Sdn.(on loan to mom!)
'87 300E (5 spd. conversion) Sold
'05 E500 Wagon

Bohdi, I got 50K miles on PBR deluxe pads. And they spew out less dust than OE and Textar pads (same pads AFAIK). I think with the W124 300D that an individuals driving style has a lot to do with how many miles you can get on a set of pads because the car is so much stronger than a 617, etc.

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!