Anybody have any ideas on what might be causing so much play in the Brake Pedal? Any advice "In General"? Thanks!

-Brian

Oh, I asked him if he had bled the brakes and he said, "Yes".

 

Did he bleed them in the correct order?

 

Given the work done my crazy idea is to check the rubber lines to the calipers.


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Two years ago I replaced the front and rear pads on my 2002 ML320 (now, with 170k miles). Afterwards, I noticed the brake pedal was soft. It would stop the ML with no problem, but now the pedal would almost go to the floor. I check the brake fluid level and even bled the brakes, but the pedal was the same. Again, the ML would stop easily, but the pedal would be "soft" or "lots of pedal", but stop the ML safely.

So, by your own admission brake pedal feel/travel is somewhat different then most. Vehicle stops on a dime with pedal 3 inches from the floor. Yes, you can push it further but why would you?

 

After I replaced the pads two years ago, I did not have any problem stopping the ML. The pedal had a lot of "play" but there wasn't any problem stopping. Over time, I found myself automatically pumping the pedal, which shortened the play of the pedal.

My wife drove the ML once and refused to drive it any more with the pedal having so much play.

=Brian

 

I spoke to the manager of the garage: A second Mechanic at the shop believes that the new booster is bad. How he determined that, I don't know. The manager said the mechanic is sure the Master Cylinder is good, so the booster must be bad. They have ordered a new booster from Dallas and it should be here (Birmingham) by tomorrow (Thursday).

I'll update the thread with the results of the new booster.

It bothers me that I'm spending $2k on an ML that's probably worth $3k.(2002, 170k miles). Oh well...

-Brian

 

Brake booster will not fix excessive pedal travel.

Since search engine here is FUBAR I have used just generic Google query. "w163 soft brake site:benzworld.org"

Here are results:

First. Moderator of this forum @cmitch starts a new thread. Ends it with "Huh?" Really. https://www.benzworld.org/threads/very-soft-brake-pedal-2002-ml320.1537123/

Second. Again no resolution. https://www.benzworld.org/threads/2000-ml320-brake-booster-problem.1636295/

Another. Again. https://www.benzworld.org/threads/spongy-brakes.2076553/

Do I need to go on?

 

I would put my money on flexi hoses .The booster can be checked by -first you start the car with your foot on the brake pedal now switch off the engine still keep foot on brake .Push pedal down a few times till it is on the floor boards ,hold it there .Next step is while your foot is still on the pedal with the pedal right on the floor start the engine up ----good booster foot lifts up as the pressure biulds in the booster . Bad booster foot moves very little or not at all .

 

FWIW, my ML500 is about the same. Effective brakes - decently strong, but spongy pedal quite a bit softer than average. It works better than it 'feels'.

The E-wagon, w210 has both great effectiveness and great feel.

On the ML, I was thinking I have a bit of wear on the Master Cylinder & rubber hoses are flexing, too.

Matt in Australia had gotten a set of 4 braided steel brake lines he was going to install and let us know how they work.

Hey Matt, are you 'reading the Air-Mail' down under - did you ever test them out ?

Mine isn't so bad I'll tear into it. But keeping an eye on it !

Best regards - David in Texas

 

FWIW, my ML500 is about the same. Effective brakes - decently strong, but spongy pedal quite a bit softer than average. It works better than it 'feels'.

The E-wagon, w210 has both great effectiveness and great feel.

On the ML, I was thinking I have a bit of wear on the Master Cylinder & rubber hoses are flexing, too.

Matt in Australia had gotten a set of 4 braided steel brake lines he was going to install and let us know how they work.

Hey Matt, are you 'reading the Air-Mail' down under - did you ever test them out ?

Mine isn't so bad I'll tear into it. But keeping an eye on it !

Best regards - David in Texas

I ended up selling the ML55 before I fitted them but I gave them to my friend to install. I don’t know if he ever did.

 

I state clearly a path to repair could be CHECKING FOR RECALLS & BULLETINS. WAS IT NECESSARY I get a rude email? FYI I Used my car as an example. The fact I don't know the person asking question skill level I thought an example might help.

 

The mechanic now believes that the ABS Pump is bad and has ordered a used one from the salvage yard.

Anyone have any thoughts on this latest diagnosis? Will the ABS Pump cause lots of play in the brake pedal? Thanks for your response!

 

The mechanic now believes that the ABS Pump is bad and has ordered a used one from the salvage yard.

Anyone have any thoughts on this latest diagnosis? Will the ABS Pump cause lots of play in the brake pedal? Thanks for your response!

It’s very doubtful it will make any difference at all. I would be looking at the brake lines first as well. Get a set of verniers and place them around the brake hose in different positions and get someone to press on the pedal with the engine running and see how much they expand.

 

Here is set of hoses for W163.

Goodridge Braided Brake Hoses for Mercedes ML W163 | Official Goodridge Distributor, DriftShop.com

Choose security and performance without compromise with these Goodridge Braided Brake Hoses for Mercedes ML W163

www.driftshop.com

 

Like others have said, look at the brake hoses especially those to the front calipers.