My Mercedes has been making a really irritating rubbing noise at low speeds which I think has been coming from the nearside rear brake, it doesn't roll properly on an incline in neutral and the fuel economy doesn't seem to be where it should be. Its been like this for a little while, so I've finally snapped and bought a new rear passenger side caliper and pad retaining pins kit for the Mercedes, I am moderately sure its the piston not retracting properly. A rebuild kit was £35 or an entire refurbed caliper was £41 so that won out. It also developed a rattle noise when decelerating as the engine revs drop between 1500 and about 1300 rpm which I'm fairly sure is a heat shield. I set too investigating that too.

The caliper I ordered duly arrived and I set about fitting it, getting as far as having removed the pads and retaining pin, and disconnected the brake flexi from the old caliper before realising the new one was wrong. Specifically, it was for a 278mm rear disc, whereas my C180 has the SPROTS 290mm ones. Bother.

So swapped it all back to the original caliper and fitted the new retaining pin since the old one was a bit grotty. Duly enlisted my neighbour to do the pedal end of bleeding the air out. This was going swimmingly, right up to the point this happened

Bother again. Well thats that b0rked isn't it? It sheared off as I tightened it up, so the stub was at least preventing the brake fluid from escaping, but I wasn't confident enough to drive it like that, so it was off to the local Motor Parts Direct for a new, correct caliper. Mercifully they are only 20 minutes walk away, they relieved me of £98 + £53 surcharge and gave me the right caliper.

Back to HQ and knowing what was required I quickly swapped over the old caliper for the new one while my wife was out at work

Old one off, flexi undone and swapped to the new one

Pads swapped over as they still have loads of meat left on them and they're worn to the discs anyway (which are also fine). Used the new slide pin and retaining clip thing to keep it all where it ought to be.

When my wife got home I got her to do the pedals as I carefully bled the caliper end (without shearing the bleed screw this time). But the important question - did it fix the sqeaky noise after a motorway run?

No, of course it didn't. FML.

So, I think the only possible option now is that its the other (drivers) side. The fronts are fine, and have had the sliders lubricated twice in the last 2 years, the noise is definitely coming from the back, but only after a run, followed by braking, then moving again at <20mph speeds. Its a constant rubbing noise, so I'm fairly sure its not a warped disc, and is a caliper piston thats slow to retract. I'll have to buy another caliper for that side, but it won't be this week.

I did get my £53 surcharge back though, and have returned the wrong 278mm caliper for a refund so I'm only £100 out of pocket.

Also I can't find where the rattle is coming from, the engine bay heat shields are fine so it must be further back. I'll have to get it on the lift and see if anything looks iffy.