bakestein1

So I’m getting the “check brake pads” message on my GLS550. I pulled the front brakes but the wear was minimal, still plenty of pad left. The brake sensor had not touched anything, as there was still lots of pad before it touches.

It could be the rear brake sensor, but without taking the tire off (the key bolt is starting to strip so I can’t) the right rear seems to also have plenty of pad.

What else can cause this message?

Thanks!

chassis

Rear brakes wear faster than fronts on most MBs. Reason is the assist systems use rear brakes and the quantity of pad material when new is such that the rears need replacing before fronts.

Fix your wheel bolt and replace your rear brake pads and rotors.

bakestein1

Thanks again!

fiveeleven

I had the same situation a few months ago. The outer pads looked fine on all four wheels. Took off all wheels for a closer examination and turns out the inside pads on the rear were worn down pretty good. Front pads were in great condition.

BlownV8

How many miles on your GLS?

fiveeleven

Bought mine CPO with 33k on it, have 51k now. The way the pads and rotors look, probably had pads and rotors changed before I picked it up. Probably change the rear rotors with the next brake pad change.

BlownV8

I would just replace the rear pads that are worn. The inside right rears seem to wear the fastest if you have Distronic. That's also the location of the brake pad wear sensor, coincidence? Just make sure to grease the sliding pin since it has a tendency to seize and cause excessive pad wear.

bakestein1

80k

bakestein1

Sliding pin? The caliper holder? I put new bolts in, as they came with from flip euro.

bakestein1

Off topic…
I replaced the engine air filters myself, and on the top of the engine is what looks like a second filler port for coolant…same markings on cap. Is it the same as the other?

BlownV8

On the rear, the inner brake pads slide in and out on pins. The bolts they sent you attach where the slide pins go into the caliper brackets. Those pins require grease, or they will bind, and your rear inner pads will wear quickly.

threeMBs

Yes same coolant, except that port is for cooling the turbos and not the radiator/engine.

bakestein1

Thats cool, thanks, however, what tells me to check it? I don’t recall anything about it in the owners manual. How to measure? I can’t figure the regular one out…now there’s two?!
🤪

bakestein1

BTW, I did not add grease to the bolts, just used the new ones that came with the brakes pads (FCP Euro).

bakestein1

Well, that as fast!
I replaced my rear brakes ~7 months ago. I did not replace the rotors, as they did not look bad enough to do so. I have a check brake pad message as of this week. I thought it was the front brakes, as I did not replace them and that made sense. It was not the front! After 92000 miles, my front brakes still have plenty left on them…which is curious. The front sensor had not begun to be worn.

I checked the rear and while the pads do look like they need replacing soon, it seemed the sensor had not started to wear either.

Question…the front and rear sensor are slightly different. How does the rear sensor work? Is it the main body that needs to start wearing or the “finger” that sits on it?

Question…what could be the cause?


Thanks for your time!

In Christ…

BlownV8

The problem on the rears is you did not grease the sliding pins. They will not release properly, and it will cause excessive rear brake pad wear.

bakestein1

What grease and where? The boot?

bakestein1

Question…the front and rear sensor are slightly different. How does the rear sensor work? Is it the main body that needs to start wearing or the “finger” that sits on


Thanks for your time!

In Christ…[/QUOTE]

Does anyone know how they work?

bakestein1

BTW, do you have to grease the front pins as well? I just did those.