Front Wheel Metel on Metal Squeal

Took car to very trusted mechanic who pulled brake pads, which were OEM installed 15,000 ago by dealer during Certified PreOwned Prep. Brake pads had very little wear but the pads were cracked and flaking at the edges. We did not pull the rotors, visually they looked OK. Braking performance was normal and did not pull to the side or squeak (except as described above.)
Mechanic replaced pads on both front wheels. After that, all seemed well, no squeaks/squeals or abnormal sounds.
Fast forward two weeks. Damn sound came back after a 5 hour drive. Just as bad as before.
Fast forward one month. Did not do anything after the one time return of the squeak. It’s now been one month, no squeak.
Below is a link from the W219 forum of a member who appears to have a similar problem.
https://mbworld.org/forums/cls-coupe...ide-wheel.html
Any thoughts as as to this problem?
Last edited by RNajarian; Aug 21, 2018 at 08:02 PM. Reason: Update

Two months later, about 2,000 more miles on odometer and I am frustrated to report the squeak returns occasionally, from same front driver wheel. When they removed the brake pads after the initial visit to the mechanic I was shown the top of the brake pads which were peeling away in sections ranging from 1/2 cm wide and about 1/4 cm deep shaped like a triangle. There were three maybe four of these breaches.
I suspect the part that is causing the squeaking is likely a defective or possibly slightly warped rotor. The rotors are drilled and I wonder if one of the holes is maybe somehow causing these triangular shaped defects.
When the squeak returns what I have been doing is driving about 20 feet with a foot on the brake and the other on the accelerator. Of course I’m doing this in a parking lot and not on the freeway. The reason is that I’m thinking with the brake depressed and the car moving it may break these little defects of the pad off. After doing so the squeak stops. . Whether it is related to my actions or not I do not know. I am due for an oil change so at that point I may have them pull the rotor and turn it and see if that helps if not I am quite frustrated as to this annoying development





