2000 Mercedes Benz ML320 Brake pedal fade

CARFIXED

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2000 MERCEDES BENZ ML320

Brakes problem
2000 Mercedes Benz ML320 6 cyl Front Wheel Drive 88000 miles

Hi, I just put pads on the front of my 2000 e320 Mercedes. Just like I have done on all cars for the last 20 years. I pulled the calipers, put a c clamp on, pushed the pistons back, installed the new pads.

I never opened the hydraulic lines.

The car's brake pedal went to the floor.

It worked fine before I put the pads on, I just had pad wear.

The only thing I can figure is that I pushed the hydraulic fluid backwards and blew something. Master cylinder? Now when I push on the brake pedal I hear a squishy sound like air. I think the booster is working though because when I pump the pedal the brakes pump up and work good. If I stay off the brakes for a few minutes the pedal will go to the floor again. I thought maybe it was a computer problem. I unhooked the battery for a few minutes and hooked it back up. No change. I had the abs and brake assist and baf lights flashing until I drove the car awhile then those lights went off but the pedal still goes to the floor. What the heck did I do wrong?

5 Replies

MERLIN2021

MECHANIC
17,250 POSTS

Is the ABS light on? If not, it sounds like the compensating port in the master cylinder. On ABS brake cars its best to open the bleeder, then push the piston basck! Don't know if it will help, but try bleeding it, did you at least remove the cover on the master before you C clamped?

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Sunday, April 27th, 2008 AT 10:01 AM

CARFIXED

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Yes I did take the cover off the master cylinder and the fluid did rise when I used the c clamp. I agree that I should have opened the bleeders because I obviously blew something. Compensating port? Does that mean I must now replace the master cylinder? The abs and baf or ba something lights came on until I drove for about 10 miles then they went off. The brakes work but the pedal goes to the floor. It feels like the back brakes are coming on first and the front end will not "dive" unless I pump the brake first. If I pump the brakes up first then stop quickly the brakes work good and the front end will dive. My wife hears air or a squish sound if she steps on the brakes with the engine running as the pedal goes almost to the floor. I will always open the bleeders in the future but I am where I am now. What next? We just went out and my wife pumped the brakes rapidly while I listened under the hood. It sounded like air near the booster firewall area. My wife closed the doors and said the sound was louder inside. Then she smelled an odd smell which I assume is brake fluid. So, there must be something near the steering column above the drivers feet leaking air and maybe brake fluid. It is all covered up so it looks like I will have to take the plastic cover off and lay down and look up in that area for a master cylinder, booster, hose etc leak inside the car? Folks I need help with this one. Bob and Ken dont charge anything for you to register and only take donations. If we all contribute to their website it will help us all so sign up please. I need your help. Thank You Rick

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Sunday, April 27th, 2008 AT 10:16 AM

MERLIN2021

MECHANIC
17,250 POSTS

You may need to go to mercedes to have it scanned for ABS codes. Did you try bleeding the lines at the master? And the calipers?

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Monday, April 28th, 2008 AT 2:21 AM

CARFIXED

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I did bleed the lines at the master and abs system but have not yet blead the calipers. I did not think I needed to do that since I never opend the line system. I will do that today and keep you posted. If bleeding the calipers does not work I will go to Mercedes and have the scan. Thank You Rick

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Monday, April 28th, 2008 AT 7:10 AM

MERLIN2021