Squishy brake pedal....

Changed out the master cylinder with a fresh MB part - bled well with a hand-vac initially. Still squishy. Then went back and bled manually with a buddy at the pedal, still squishy.

Suspecting a possible bad new part, I swapped it out with our salvage truck's master cylinder today and bled manually (14,xxx mile part), used 1.5 quarts of fluid to make sure it was well bled. No air in lines. Still squishy.

Checked the factory service manual, nothing trivial about bleeding brakes. For some reason there isn't a bleeder on the ABS unit, but I did my best to bleed it by cracking each of the 4 lines with pedal pressed; still squishy.

No fluid leaks at calipers.

Only thing left is the ABS unit, and I did note in the factory manual that there could be possible internal leaks in the ABS unit with no evidence, so that's where I'm at. I got the unit out of our salvage truck and will be swapping tomorrow if time allows and see what happens. I'm about to use kerosene and matches on this thing....NEVER had a problem with brakes on any other vehicle I've ever worked on before!

Pedal takes one pump for soft brakes, and two for a hard pedal while driving. Not good for panic stops...

Why did you change the master cylinder?

If there is air anywhere it will cause the symptoms you describe. Air can remain in the ABS system even after a traditional brake line bleed. To get it all out you need a scan tool which operates the ABS pump/system during the bleeding process.

There have been reports of air in the brake system being traced to faulty ABS units. As I recall the symptoms were that the pedal would get soft, bleeding would restore, soft pedal would return after a time. The air can leak into the ABS system during down time without necessarily showing an external leak. vic

We changed the master cylinder due to the squishy pedal, after an initial bleeding. I bled the hell out of the system and no air bubbles left. I do have a scan tool and I can see if that will help.... With this truck, the pedal is consistently squishy every time you push the pedal; it takes a double pump in order to get a good feel.

I did just order a complete MityVac pressure bleed system about 10 minutes ago mainly so I don't have to wait on an extra guy to help me. Hopefully it's $280.xx well spent..

I would check out 2 things:
1-have a buddy press the pedal and you visually inspect each rubber brake line for a bubble or unnatural expanding.
2- my father-in-law bought an E250 a few weeks ago with "squishy brakes". I bled the crap out of the whole system and STILL had to pump the pedal to get a firm feel. Turned out to be poorly adjusted rear brake shoes. I know, the Ford has rear drums and the Sprinter has rear disks, but check all the calipers for one that may "stick", or not close all the way on the first pump of the brakes.
Good luck!

Try "bench bleeding" the master cylinder first.
P

Compstall,
ALL Sprinter Brakes seem "squishy". There may be (or have been) nothing wrong with your master cylinder.
The only way to fully get all the air you have introduced into the system out of the system is to take your Sprinter to an Authorized Mercedes/Freightliner Sprinter dealer and have them bleed the brakes and the ABS/ASR unit. The ABS/ASR unit has to be activated by their MB SDS computer or a DRB-III diagnostic unit.
Please read this Thread on this forum for what you need to know about the normal soft brake pedal feel on all Sprinters:
https://sprinter-source.com/forums/showthread.php?t=3114&highlight=soft+brake+pedal
Roger

Re: MB Squishy brake pedal....

gary 32 said:

Roger is right but to me all Mercedes have a soft brake pedal feel.
I bleed them, find a low traction surface like gravel lock it up a few times and let the abs actuate then re bleed. I have seen air exit the system after this procedure.

I use a Motive pressurized bleeder with an in fluid catch can.
A one man deal and you can do it with the wheels on.

Click to expand...

Sounds like a decent DIY method to me.

Sprinter brakes may have a soft feel, but when they are properly operating it doesn't take an initial low pedal pump followed by subsequent pumps as was described to work properly. The soft feel still stops the vehicle with one go. vic

Anyone know where to buy the DRB, I may just get one.

Also, I know the pedals are typically soft, but this one is too soft. I've got 10 other Sprinters to compare it with.

Brake rotors wore down to far what fixed ours. after all that bleeding.

I found that pressurized bleeding works better than vacuum bleeding, as well as the above mentioned "take it out on the road and make the ABS cycle" than bleed again.

I would also check the amount of vacuum your brake booster is getting. The engine mounted vacuum pump can wear out. A stuck caliper can also lead to some squishy feel.

I'm feeling good right now that I'm not the only one struggling with this. Threw in the towel today and took it to a different shop to let them play with it. They've had it all day; might get it back tomorrow, heh.

bigstevex3 said:

Brake rotors wore down to far what fixed ours. after all that bleeding.

Click to expand...

Mine was quite bad at 150,000. Dodge dealer tried to sell me 4 new calipers. I put new rotors and pads on the front myself.... problem solved!

At this point I'm letting this truck be as it is. All our other trucks take about 1/2 pedal travel to stop; this one takes about 3/4 pedal.

I threw in the towel and took it to a shop down the street and let them jack with it for two days. They even put the new master cylinder back in it, and swapped out the ABS unit. Nearly the same result.

Only question I have is, I know and understand shops can be expensive, but $420 to change the master cylinder?? TWO mount bolts and two brake line nuts, under 10 minutes to do. They already charged $100 to bleed it, which is what took the longest!

Soft brake pedal I usually find is a seized front caliper slide. Take cover off the bottom slide on each front caliper and if its full of rust then its seized and needs a new slide kit fitted.

Compstall said:

At this point I'm letting this truck be as it is. All our other trucks take about 1/2 pedal travel to stop; this one takes about 3/4 pedal.

I threw in the towel and took it to a shop down the street and let them jack with it for two days. They even put the new master cylinder back in it, and swapped out the ABS unit. Nearly the same result.

Only question I have is, I know and understand shops can be expensive, but $420 to change the master cylinder?? TWO mount bolts and two brake line nuts, under 10 minutes to do. They already charged $100 to bleed it, which is what took the longest!

Click to expand...

Wow, glad they were pros and new what they were doing. Not fixed--talk to a lawyer
For that much I think a sprinter dealer would do it
At least I think they can

Way late to the party, but I think the "squishy" brake pedal is a Mercedes thing. For the record, I have a lot of experience in the other German marque, BMW, on and off a race track. No matter what model BMW I drive the brakes all feel the same. Firm and linear. The BMW brake pedal feel is the same even with Performance friction or stop tech BBK.

Every Mercedes I have driven had the " squishy" feeling brakes. E350, squishy. E350 convertible, squishy. German Vito rental van, squishy. I now own a 2013 AS Inetrstate and compared to the e450 based RV I had the Mercedes brakes feel great. Go figure.

At the end of the day the Mercedes mind set is focused to a buyer who wants a solid German car with more luxury and comfort with a compromise on sportiness. In my case, with the Airstream, the Mercedes chassis hits that nail right on the head. However. Compared to my old Winnie, the Sprinter is a sports car.

Here's where I'm at with this thing: Over the last couple months the guys have been complaining to me that the front end is binding up. I did change the front shocks but of course wasn't given enough time to complete the job, i.e., get an alignment done. The first time I got it back I took the wheels off and checked everything to make sure a bolt didn't come loose or any other visual binding, stuck, or jammed parts. Everything looked fine and I even loosened up the bottom mount bolts and retorqued. Did this three different times, but could never get the problem to duplicate itself when I was around; it minded its manners and drove fine.

Last week I was finally able to get it in for an alignment. They loosened everything up and started from scratch. Straight as an arrow, and when I pulled out of the parking lot and let off the gas, it finally did what the guys were talking about. I immediately knew it wasn't any binding issue in the suspension. The right front brake got a random signal from the ABS unit and tried to lock up for about 1/2 a second.

So now I know it's a brake issue. The ESP light is on, and I'm confident the soft pedal is the cause of the ESP problem, which is probably confusing some component in the system. It only did this one time for me and drove fine otherwise.

I called a shop near Seattle that specializes in Sprinters and they mentioned that the vacuum pump could possibly be weak, so I swapped the vacuum pump from our salvage truck (11,000 miles on it). That improved nothing. When I got home I ordered all new hard plastic vacuum lines from the vacuum pump to the master cylinder to rule them out. Waiting on them to come in.

Still scratching my head.

Is your truck a 2500 or a 3500 Sprinter? Cab and chassis or van ? As for the wheel releasing at low speed braking (ie. parking lot) Have the system scanned , probably a bad speed sensor or pulse ring . The "soft" brake pedal is a common complaint on the 3500 Sprinters especially the Cab chassis ones (campers too). All the bleeding and all the parts replacing will never fix a Soft pedal nor a "LOW" pedal. Try this - drive about 40mph with no one behind you !! perform a panic stop without pumping the pedal ... it will stop in a hurry believe me , if it doesn't and the pedal hits the floor then you have a problem. If you are comparing a 3500 to a 2500 Sprinter then its apples to oranges. The brakes on the 3500 Sprinters are inherently "squishy". Why they are that way ? I do not know.. You may be fighting with design engineering.

Carl

As you can see in post #8 I have 10+ Sprinters I work on and drive regularly, actually 12 now - picked up a used one a couple weeks ago and the guys are flying to TX to drive back a brand new 2012 model chassis cab in the next week or so. I know what a good pedal feels like and this one isn't good. We only have 3 high-top vans (one is gas), and the rest are all chassis cabs. This particular one is a chassis cab. I have no brake codes other than the ESP light on the dash.

Hi guys my 2004 dodge sprinter 2500 threw lites on in the dash abs - esp -asr malfunction . Vehicle locks in park cant move it - till i start and shutoff vehicle 3-4 times then the lights go out and i can roll again , apply brakes too hard lites on put it in park and wont release same scenario again & again ? So im thinking brakes in the front are worn - went to mechanic he says they look low on the pads ! Can barley see the pads ? New brakes ~new rotors and sensors installed , mechanic says nothing about having a good amount a meat on the old pads after i see them ? $$$ ?pads still had life , but he does mention i need a slider kit for the left caliper as its not sliding on the pins smoothly* with that i ck brake fluid and its close to the minumum line ? Mechanic adds the mopar - sprinter dot 4 fluid i provided . Pay the bill roll out the door brakes are mushy and i dont go more then 2 blocks all the lights go on ? Shut down start up and lites come on 3-4 times on the way home , finally after some hard braking this has seemed to stop no lights . But now trying to locate a parts house who sells the slider kit for the front brake calipers = any one know of a parts house or has anyone had this problem too ? Please reply johnny or johnnyvictrola@nyc.rr.com