OffroadHamster
K.I.S.S.
Whatever Mother Benz put on them from the factory.
I was missing a dust boot which I am sure contributed substantially to the frozen pin.
A Soft Brake Pedal Story
- Thread starter Wandering Albatross
- Start date
I was missing a dust boot which I am sure contributed substantially to the frozen pin.
Nhuskys
Member
2008 3500 C Class? How many miles? My 2008 3500 got a very soft pedal. Dealer wanted to sell me new calipers, brake lines, and a master cylinder, along with pads and rotors. I installed new rotors and pads myself. The pedal was fine after that. You may have worn pads, and worn beyond minimum thickness spec rotors?
I use sythetic axle grease! I also clean out the calipers, and aply a thin coat of grease on the both sides of the shims, and thin coat on the tracks where the pads slide. Basicly anything that moves on the caliper I lightly grease, and wipe down with finger just to give a thin coat of lubricant, it helps especially if you have chatter
Dax Travels
2011 Freightliner 3500 DRW
I keep the lube for the pins and protected by their dust boots. Lube is a dirt and dust and magnet. Some of the surfaces I see lube mentioned here are better dry than caked with gritty grease.
sprint2freedom
2008 NCV3 170ext
These M10x1.0 bubble flare plugs fit the ABS module on my van:
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Buy Brake Line Plugs, 10mm 1.0 Bubble, Pair, Compatible with Dune Buggy: Hydraulic Parts - Amazon.com ✓ FREE DELIVERY possible on eligible purchases
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Wandering Albatross
Active member
Now for the rest of the story. We ended up spending about 24 hours at a rest stop off the freeway changing the master cylinder, bleeding the system with a scantool to activate the ABS module, and checking the brake system for leaks, etc. We had no stuck calipers pins or anything of that nature as the brakes had been recently rebuilt. In the end, everything worked out and we able to finish the rest of our trip.
Months before we had a brake pad that was dragging and caused glazing and as a result lots of brake noise. We falsely swapped out a few brake parts chasing the issue including the master cylinder. When we first changed the master cylinder, we tried a new unit from FTE. It leaked at the reservoir grommets so we tried a second FTE master cylinder and it also leaked in the same location. The original master cylinder that the vehicle came with was from Bosch so I purchased a new Bosch master cylinder from eBay hoping for a better outcome. This was a mistake.
The "Bosch" master cylinder arrived in good order and said the brand name in the casting, but it did not look the same as the original that came with the vehicle. I think the eBay "Bosch" master cylinder might have been counterfeit because it lasted less than six months of light usage before the pedal went soft while driving and left us on the side of the road.
Luckily we had kept the original master cylinder in the vehicle along with all of the required tools (line wrench, bleeder bottle, power pressure bleeder, brake fluid, rags, scantool, etc.). After the original master cylinder was reinstalled there was some confusion about how hard the pedal should feel, but after a test drive, it turned out that the original master cylinder was working fine despite feeling a little mushy at the rest stop. It took time, but we were able to successfully fully bleed the system with a Motive power bleeder and a Foxwell Sprinter-specific scantool to cycle the ABS module.
Regarding our original brake dragging issue, it turned out that there were a burrs on the brake pad backer plate ears that were causing the brake pads to stick on the carrier and not retract properly. This problem was solved by filing the burrs off so the pads could slide properly. These were aftermarket performance pads.
A few lessons learned:
1) Don't buy brake parts off eBay because they might be counterfeit (not sure why we had so much trouble with the FTE master cylinders)
2) Traveling with tools and spare parts can be a significant help when things don't go as planned
3) Make sure your pads don't have burrs that could cause them to not slide properly
Thanks for reading about our adventure!
Months before we had a brake pad that was dragging and caused glazing and as a result lots of brake noise. We falsely swapped out a few brake parts chasing the issue including the master cylinder. When we first changed the master cylinder, we tried a new unit from FTE. It leaked at the reservoir grommets so we tried a second FTE master cylinder and it also leaked in the same location. The original master cylinder that the vehicle came with was from Bosch so I purchased a new Bosch master cylinder from eBay hoping for a better outcome. This was a mistake.
The "Bosch" master cylinder arrived in good order and said the brand name in the casting, but it did not look the same as the original that came with the vehicle. I think the eBay "Bosch" master cylinder might have been counterfeit because it lasted less than six months of light usage before the pedal went soft while driving and left us on the side of the road.
Luckily we had kept the original master cylinder in the vehicle along with all of the required tools (line wrench, bleeder bottle, power pressure bleeder, brake fluid, rags, scantool, etc.). After the original master cylinder was reinstalled there was some confusion about how hard the pedal should feel, but after a test drive, it turned out that the original master cylinder was working fine despite feeling a little mushy at the rest stop. It took time, but we were able to successfully fully bleed the system with a Motive power bleeder and a Foxwell Sprinter-specific scantool to cycle the ABS module.
Regarding our original brake dragging issue, it turned out that there were a burrs on the brake pad backer plate ears that were causing the brake pads to stick on the carrier and not retract properly. This problem was solved by filing the burrs off so the pads could slide properly. These were aftermarket performance pads.
A few lessons learned:
1) Don't buy brake parts off eBay because they might be counterfeit (not sure why we had so much trouble with the FTE master cylinders)
2) Traveling with tools and spare parts can be a significant help when things don't go as planned
3) Make sure your pads don't have burrs that could cause them to not slide properly
Thanks for reading about our adventure!
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Solera2012
Well-known member
Curious, do you think if you were at home, a "bench bleed" of a good quality Bosch master cylinder, could have been done?
Sprinters use to brands of brake master cylinders, I believe the most common brand is not bosch but TRW. I made a mistake going by part numbers, and purchased a bosch of ebay aswell.
When I removed the original it was a different part. The are where it connects to the brake booster was wrong. The oem was stamped trw and so was the brake booster. So I did digging for that style brake booster from trw then found a replacement part number.
When I removed the original it was a different part. The are where it connects to the brake booster was wrong. The oem was stamped trw and so was the brake booster. So I did digging for that style brake booster from trw then found a replacement part number.
My advice to anyone who wants to replace their brake master, is to not go by the part numbers but actually remove the damaged master and order one like it. That way you avoid buying multiple wrong parts. You can easily remove and install the brake master without having to bleed the calipers. Just make sure to bleed the master itself before tightening the brake line fittings.
Wandering Albatross
Active member
In the end we basically bench bled the original (the one that came with the vehicle) Bosch master cylinder and then bled the entire system. You can do a "bench bleed" on the vehicle by pushing in the pedal with the brake lines loose and then tighten them down, release the pedal and then repeat the process. You are basically using the brake pedal to help with bench bleeding and this seemed to work fairly well.
I have heard of some people bench bleeding the master cylinder and then not evening needing to bleed the rest of the brake system because they were able to do the swap getting little to no air getting into the lines.
I still don't know what exactly was causing the FTE master cylinders grommets to leak. It appeared to be the correct part and they were purcahsed from a reputable vender. They are supposed to be a respected European brand, but it appears that you mileage may vary!
We drove another 1k miles after the master cylinder swap and so far our old reliable Bosch unit has been working fine.
I have heard of some people bench bleeding the master cylinder and then not evening needing to bleed the rest of the brake system because they were able to do the swap getting little to no air getting into the lines.
I still don't know what exactly was causing the FTE master cylinders grommets to leak. It appeared to be the correct part and they were purcahsed from a reputable vender. They are supposed to be a respected European brand, but it appears that you mileage may vary!
We drove another 1k miles after the master cylinder swap and so far our old reliable Bosch unit has been working fine.
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Actually, I saved a bunch of money compared to oem dealer. Since the oem part was made by TRW, I managed to find the correct part on spareto cost me 47 british pound and 1 week shipping versues dealer is $474 for the same part
PMA132 - Brake Master Cylinder
PMA132 - Brake Master Cylinder manufactured by TRW applicable for the MERCEDES-BENZ and VW. This brake master cylinder is fully compatible with original part numbers 2E0611017G, 9064310101, and 9104311200.
spareto.com
Yak McGurk
New member
Couldn’t hurt to do a smoke test on the brake booster to make sure the seals are good. Could be you’re just pushing harder to get the same brake effect.
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ironbrian762x
Dunno what I'm doing; sure doing a lot of it tho
So after all of that, how is the pedal feel? Please tell me it's better because mine sucks. My symptoms are identical. Hell, it even happened at damn near the same time because I swapped the master in a liquor store parking lot full of vagrants on March 14!
I am about to go out and follow the notes in this thread because I have done all the normal stuff:
- bleeding with vacuum bleeder old-school style
- vacuum bleed with scantool on the ABS (2 quarts thru yesterday dammit!),
- scantool actuating the ABS while I just stand on the pedal and not bleeding,
- checked all lines and no leaks,
- no perceptible bulge in any of the flex lines going to the wheels,
- new master after the old one "failed" and the pedal went to the floor on the highway (hoooooly shit!). Bench bled in parking lot the same way you mentioned. Could not find TRW and Mercedes was of no help on a Friday afternoon, so Autozone to the rescue with the only one in the greater Los Angeles area (couldn't physically get to Europarts SD).
- no fluid in the booster. Master/booster interface good on reassembly.
- looked at all pads while rotating tires and nothing seemed amiss; all flash rust on rotors from a week parked in the rain was gone after a drive.
- UGHHHHHH.
Wandering Albatross
Active member
The difference between the bad master cylinder and functional one was fairly obvious when driving. The bad master cylinder feel changed during a long day of driving. When we departed in the morning it felt pretty normal, but by mid day the brake pedal was three quarters of the way to the floor for a normal stop. Emergency braking was maginal.
At this point, we bled the system one more time just in case there was still air in the system. It felt a better for the rest of the day of driving. We spent the night at the rest stop and in the morning the brakes felt soft again and that is when we did the master cylinder swap back to the original Bosch unit that the vehicle came with.
To test the brakes before leaving the rest stop, we gave it throttle with the brakes applied. If your brakes are working correctly, the brakes *should* be able to easily lock to the point that moderate throttle inputs can't make the vehicle surge forward. Note that this is how we did it because we were desperate to test the brakes before driving because the only departure option we had from the rest stop was directly back on to the freeway. There were no surface streets available for a shake down test. In general pushing the throttle and the brake at the same time isn't the best idea.
You should start to feel the brakes bite 1-2 inches into the range of motion. Maybe 3-4 inches for full lock? Keep an eye on your brake reservoir level in case you have a fluid leak. The brakes on these Sprinters are not super powerful to begin with if you are heavy, but they will feel soft if you don't bleed the brakes using a scantool to open the ABS module. I have tried to bleed the brakes after a master cylinder replacement (one of the FTE master cylinder installs) without the scantool and always found the brakes to be soft. With the ABS module actuated, you should hear noises coming from it.
The rear brake lines are long and can be hard to bleed. We had new brake fluid in our brake system so I was pulling maybe two liters through each rear brake line with multiple scantool brake actuations. We may have gone through up to six liters total by the time all the bleeding was done. This might be a little excessive, but you get the idea. I would then put the fluid that came out back into the master cylinder and move to the next caliper. One ABS actuation and a half liter of brake fluid is likely to leave air in the system especially for a rear brake. Sometimes it helps to briefly and carefully drive the vehicle and then bleed it again.
YMMY and good luck!
At this point, we bled the system one more time just in case there was still air in the system. It felt a better for the rest of the day of driving. We spent the night at the rest stop and in the morning the brakes felt soft again and that is when we did the master cylinder swap back to the original Bosch unit that the vehicle came with.
To test the brakes before leaving the rest stop, we gave it throttle with the brakes applied. If your brakes are working correctly, the brakes *should* be able to easily lock to the point that moderate throttle inputs can't make the vehicle surge forward. Note that this is how we did it because we were desperate to test the brakes before driving because the only departure option we had from the rest stop was directly back on to the freeway. There were no surface streets available for a shake down test. In general pushing the throttle and the brake at the same time isn't the best idea.
You should start to feel the brakes bite 1-2 inches into the range of motion. Maybe 3-4 inches for full lock? Keep an eye on your brake reservoir level in case you have a fluid leak. The brakes on these Sprinters are not super powerful to begin with if you are heavy, but they will feel soft if you don't bleed the brakes using a scantool to open the ABS module. I have tried to bleed the brakes after a master cylinder replacement (one of the FTE master cylinder installs) without the scantool and always found the brakes to be soft. With the ABS module actuated, you should hear noises coming from it.
The rear brake lines are long and can be hard to bleed. We had new brake fluid in our brake system so I was pulling maybe two liters through each rear brake line with multiple scantool brake actuations. We may have gone through up to six liters total by the time all the bleeding was done. This might be a little excessive, but you get the idea. I would then put the fluid that came out back into the master cylinder and move to the next caliper. One ABS actuation and a half liter of brake fluid is likely to leave air in the system especially for a rear brake. Sometimes it helps to briefly and carefully drive the vehicle and then bleed it again.
YMMY and good luck!
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Did you remove the front calipers and made sure the floating pins were floating and not stuck? If not go do it to atleast the front calipers, make sure those pins are not stuck and move freely. I would also clean the inside of the calipers while you are at it, and apply a very thin layer of axle grease to the pins, the backs of the pads, the silencers where the pads slide.
ironbrian762x
Dunno what I'm doing; sure doing a lot of it tho
Did all that just now. Everything got wire wheeled and greased. I don't know how thick the pads should be but they're beefy. The rear pads are worn enough (uncertain of a depth spec on a 2005 2500 with Ate calipers) I'm going to replace them, so I'm waiting for pads to show up tomorrow before I can do any further testing. I'm also going to borrow a buddy's Motive pressure bleeder for this next effort. Vacuum leaves me less than confident because I'm never sure if the bubbles are from around the nipple/fitting or from the lines.
Were your guides pins stuck, did you have to hammer them to remove them? The caliper has to freely float so that the piston compress and retract without binding of the pins.
Wandering Albatross
Active member
FYI, this Motive bleeder (European version) works well on our Sprinter. 15 psi seems to be a good balance point. If you go too high with the pressure, the reservoir grommets will start leaking. I have used it a bunch of times!
There is a small chance that the Autozone master cylinder is bad out of the box. I have had problems with parts quality these days.
Also, when you bleed the brakes, don't drastically over tighten the bleed screws. If you overtighten them, it can cause them to leak. We had this issuse because a previous mechanic had over tightened them and when we loosened them and then tried to seal them again, they kept leaking because there was a radial indentation in the sealing surface. Basically the bleeder screws are softer (from what I could tell) than the caliper steel so you want them tight enough to stay put, but so tight that it damages the sealing surface. In the end, we had to replace all four bleed screws.
There is a small chance that the Autozone master cylinder is bad out of the box. I have had problems with parts quality these days.
Also, when you bleed the brakes, don't drastically over tighten the bleed screws. If you overtighten them, it can cause them to leak. We had this issuse because a previous mechanic had over tightened them and when we loosened them and then tried to seal them again, they kept leaking because there was a radial indentation in the sealing surface. Basically the bleeder screws are softer (from what I could tell) than the caliper steel so you want them tight enough to stay put, but so tight that it damages the sealing surface. In the end, we had to replace all four bleed screws.
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ironbrian762x
Dunno what I'm doing; sure doing a lot of it tho
Great tip, thank you! Those suckers are fine-thread, so I never crank the heck out of them, but I'm aware that I'm not the first owner or the only guy to put hands on them. Thanks for the vote of vote of confidence on the Motive.
The pins weren't stuck at all on the front. I specifically looked for backing plate tabs and the anti-vibe plate and cleaned everything too. On the rear, they weren't seized either, but the pads definitely were not moving very well across the caliper due to rust. If at all. I'm honestly not sure. Fingers crossed when I get those in the AM, it's like magic and I've wasted all this time bleeding when I should have just pulled the rear wheels off.
Next up in the parts cannon are new flex hoses. I've heard multiple people talk about them failing internally. Hope I'm done with parts though.