Help! I Can't Figure This Out - PeachParts Mercedes-Benz Forum

Ockman · #1 10-12-2004, 08:08 PM

I have a 98 ML320 with 57K miles and every few months a strange thing happens when driving it. I call it uncommanded braking of the right front wheel. The vehicle becomes very cumbersome and will hardly move unless you really get on the pedal. When you release the gas, the car comes to a stop as though the brakes were applied. The right front brake disc area and wheel are very hot when this happens. All the other wheels are normal. There are no warning lights that indicate a problem.

Here is the part I don't understand. If it were only the right front brake that was malfunctioning, let's say a caliper sticking, then wouldn't the vehicle pull to the right when this occurs? It doesn't. Instead, it tracks straight ahead. The dealer replaced everything in the brake system, calipers, rotors, brake lines, pads and master cylinder under warranty. That didn't fix it. It still does this every few months and hit me today in stop and go traffic.

I tried going into low range and back out thinking that might help. It didn't. I tried everything I could think of but the only thing the seems to correct it temporarily is waiting for the brake and wheel to cool. When this happens the transmission also shifts normally so I doubt that has anything to do with it...but maybe it does. After it cools she drives fine again.

Of course I'm out of warranty now and would like some ideas on where to start troubleshooting. I've lost confidence that the dealer can fix it..he had a go at it and failed. Any ideas?

lyonstexas · #2 10-12-2004, 08:27 PM

On previous vehicles, I have had a problem which appeared under warranty and was not resolved while in warranty and I pushed the dealer to make it right as it was their misdiagnosis/inability/ineptitude that caused me to be out of the warranty period. If the problem is brought to their attention during warranty, it is theirs to resolve no matter how long it takes.

Tim

Gilly · #3 10-12-2004, 09:01 PM

Never heard of this. It would be pretty tough to diagnose if it only happens every few months. To be honest, I'd dump it (while it's not acting up of course).

Gilly

Ockman · #4 10-12-2004, 09:52 PM

Dumping it is not an option Gilly. I already tried that on my wife and she won't hear of it. She loves that ML....she and that "truck" have gone thru all the growing pains of the "early ML320s" and now she's is a pretty good vehicle except for this problem.

How about some ideas? The thing that has me puzzled is it doesn't pull to the right and yet that is the only wheel that is very hot. Doesn't make sense!

nglitz · #5 10-12-2004, 10:01 PM

Well designed suspensions don't let the brakes don't "pull" their wheel to that side.

No idea what's causing yours to apply themselves.

I've heard that old hoses sometimes start to come apart inside and the loose parts can act as a check valve. This would hold the brake on after it's applied. Sound like yours? Or does yours apply itself without your help?

Could it be a bearing?? Is it the brake rotor that's the hottest part or the bearing housing?

This is a tough one.

Ockman · #6 10-12-2004, 10:45 PM

It's definitely the brake disc that is hot, not the wheel bearing. The dealer already replaced the brake line and it continues to act up every few months. I still don't get why it's not pulling to the right if the right brake is sticking. If the other wheels are trying to compensate for the right pull they would be a bit warm too, wouldn't they?