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A little puzzler here.

1K views 7 replies 5 participants last post by  Darkmann 
#1 ·
last night I washed my truck. usually after a good washdown, I run the truck a mile or two to get all water "dislodged" then give her a final wipe. Didn't do it yesterday. This evening, I get in, put it in reverse, her tranny shift, mirror tilt, parking brake off but car won't budge. So I try again, same result. I got out, lok around for obstacles under tire, free and clear. So I'm thinking stuck pedals on the rotor. So I get back in, put in reverse and rev to force the issue. "POW", that's the sound that came from around the drivers' side front tire, and vehicle moves. Get out of garage and check around and all seems fine. What the heck just happened? Assuming it had to do with the brakes, did my front pads stay stuck onto the rotor since yesterday night? Could I have possibly damaged something? It can't be the parking brake - operates only rears. What else could it be? All I can think of is that water got soemwhere into the brake hardware (probably torn pin boots), caused just enough corrosion to push the pads onto the rotors. I'm going in tomorrow for an unrelated problem - leaky rear lamp gaskets!!! Maybe they can find out what happened.
 
#2 ·
It's actually fairly common.

After I wash my truck I often only move it 20' into my garage. Even with that, the water on the brakes causes a little oxidation that makes the car "stick" the very first time I try to drive it. Sounds like yours was a little more prominent than what happens to mine but I still doubt it's anything to worry about.
 
#3 ·
I can understand the rears getting stuck because of the emergency brake. The fronts have

floating calipers, I believe. As long as the brake pedal is not depressed, there's clearance (there should be!!!) between the pads and the rotors. The calipers have to be "energized" somehow for the pads to stay on the rotors that long. And that's what's bothering me - bad calipers or what? All this, assuming that the problem is related to the brakes!!! Anyway, the service manager said they'll check it.
 
#5 ·
Are you sure it was the front brake....?

Did you apply the Parking Brake after washing the truck and left it parked overnight?

Someone in another discussion forum (I forgot which one, not Edmunds, maybe m-class list) had his parking brake "stuck" after washing and parking the ML.

It also happens to me if I don't drive it around after washing my truck, and it's definitely the parking brake (if I don't apply the parking brake after wash it's ok; so if I don't have time after washing it I leave the parking brake un-engaged and since it's on my level garage floor it wouldn't damage the transmission gears in Park).
 
#6 ·
Wait a second here...

Just to clarify, when you said "parking brake off", does that mean that you left the parking brake off overnight, or did you leave it engaged and then released it in the morning, just before you were going to move off?

If you leave the parking brake on without letting the water dissipate in the parking drum (in the disc), rust can form overnight and rust the shoe to the drum, causing exactly what you described.

Unlike many vehicles out there, MB's parking brakes work <b>very</b> well. Most parking brakes "give up" when enough throttle is applied. Heh, this has some advantages in the snow, when you're fooling around [;)]

Perhaps try low range next time? You won't need to rev the engine quite as much, LOL.
 
#7 ·
Re: Are you sure it was the front brake....?

...wouldn't damage the transmission gears in Park).
Actually it doesn't damage the transmission "gears". When you put the vehicle into park, a parking pawl (small piece of metal) is "stuck" into the cogs. This is why it's important to apply your parking brake as often as possible, so that it minimises stress on this part. If you don't, (with domestic cars especially), it can break off in time and then you won't have anything to hold your car back in the "Park" position without the parking brake engaged. Yikes [:0]
 
#8 ·
I always engage the parking brake when I turn ignition off and in P. What I meant was that I

disengaged the PB and the truck didn't budge - had it engaged overnight as I always do. I know it wasn't the PB 'cause the POW sound definitely came from up front. Anyway, they looked at the hardware today and everything's fine. I also found out that there is very little pad-to-rotor clearance on these trucks. And Drew, i didn't have to rev real hard, just a little push on the pedal to unlock things.
 
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