W163 2000 ML 270 CDI brakes stuck on (intermittently)

Wearethesound

Member
Joined
Dec 21, 2014
Messages
31
Car
2000 ML270 CDI
So I just changed my front brake pads and was doing a test drive and about half way through the drive I noticed it was harder for my ML to accelerate and when I let off it would decelerate quickly. I pulled over and sure enough both bakes where smoking hot. I let them cool abit and headed home. After they cooled completely I went out again this time I put the petal to the floor at about 35-40 mph to activate the abs. I got some tire squeal from the front tires so I tried it again this time the abs kicked in and stopped without locking the wheels up. So I test drove it again. This time all seemed great until about 20 mins into my drive the BAS/ESP light came on and I noticed it was decelerating fast again. I got home and this time only the left front was extremely hot. Should I give it a few hard stops again? Or is there something else I should be looking for??? I lived everything up when I did the job and even polished the bolts. (Mine are not the pin style where the pads drop in, you pull the caliper to get them out just FYI) thanks for any help anyone has to offer.
 

Stratman

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Jun 15, 2003
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5,001
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Sunbury
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W203 C200 CDI '04Estate
Do the pads slide easily in the calipers? If they're a tight fit they could be expanding as they heat up normally after an application, and sticking on.
 
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Wearethesound

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Joined
Dec 21, 2014
Messages
31
Car
2000 ML270 CDI
They did, I think it's fixed now. I pulled the mount bolts and they where so tight I couldn't push them through with my hands so I shaved a few mills off them, rounded them out and gave them a good polish (about 1.5 hrs per bolt due to them being such a hard tempered steel) a little copper grease and all good. I was about to rebuild the calipers but I noticed when brake pressure was applied then released the piston would retract ever so slightly (barely noticed it) and a tiny bit more with pressure from my thumbs (don't try at home possibility of thumbs getting swished) (no brake pad installed) so I make the call it mustn't be the caliper but the mounts. So far seems I was right took her for an extra long road test and found the wheel area warm to the touch but touchable as to where before It was visibly smoking after a much shorter drive.
 
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Wearethesound

Member
Joined
Dec 21, 2014
Messages
31
Car
2000 ML270 CDI
Also now for some reason my BAS/ESP light comes on about 10 mins into drive and stays on. I know my brake sensor was melted after the second test drive. Is this related to the system?

Knowing what little I do BAS (brake assist system )?? And ESP (electronic slip program)?? I was thinking maybe related???
 

Stratman

MB Enthusiast
Joined
Jun 15, 2003
Messages
5,001
Location
Sunbury
Car
W203 C200 CDI '04Estate
There's a wheel speed sensor on the wheels, it magnetically reads the teeth on the toothed ring tucked in behind the brake disc. It most definitely contributes to the ESP and ABS as it's what tells both systems the wheel speed. It's easily dislodged when working on the brakes so make sure it's pushed fully home in its seating and that the wires haven't been severed.

BAS Brake Assist. When the car senses you're doing an emergency stop it takes over and stops the car like you wouldn't believe.

ESP Electronic Stability Program(me) An advanced form of traction control, The computicle measures individual wheel speeds, steering wheel angle and other parameters to decide if everything is in order and if it isn't it brakes individual wheels to keep you on the tarmac.
 
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remlap

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Jul 29, 2015
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13
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ML 270
When i changed mine about a month ago i found that the new pad back plate was a smidgen bigger than the aperture they fitted into, I lightly ground the edges down so they slipped in easily, as the pads need to move back freely to release the disk. If yours went in quite easily i would suggest an inspecton of the calliper pistons just to make sure they move in and out freely
 

remlap

New Member
Joined
Jul 29, 2015
Messages
13
Car
ML 270
When i changed mine about a month ago i found that the new pad back plate was a smidgen bigger than the aperture they fitted into, I lightly ground the edges down so they slipped in easily, as the pads need to move back freely to release the disk. If yours went in quite easily i would suggest an inspecton of the calliper pistons just to make sure they move in and out freely
 

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