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2005 Sprinter Brake pedal falls away or soft
sprinterguru
Member Posts: 24
Do you have a Sprinter with soft pedal or the brake pedal falls away almost to the floor? Three things you need to check or do. 1. If you have just changed brakes or opened the system to air you may need to bleed the brakes. You can do this the old fashioned way pump, hold, crack the line or the preferred way would be to do what Daimler calls the Exceptional bleeding. This is done using a Daimler scan tool at your dealer.
2. Check the vaccum. You should have 20 to 22 HG at the booster, if the pump is pulling too much the booster actually will pull the pedal away from you. Also inspect the check valve at the booster. I have seen these cracked also.
3. If the vaccum is ok your problem is most likely in the booster.
4. Dont let a dealer talk you into changing the ABS control valve for $2k that will not fix your problem.
5. We are assuming you have inspected the master cylinder for internal bubbles.
Hope this helps.
Roy
2. Check the vaccum. You should have 20 to 22 HG at the booster, if the pump is pulling too much the booster actually will pull the pedal away from you. Also inspect the check valve at the booster. I have seen these cracked also.
3. If the vaccum is ok your problem is most likely in the booster.
4. Dont let a dealer talk you into changing the ABS control valve for $2k that will not fix your problem.
5. We are assuming you have inspected the master cylinder for internal bubbles.
Hope this helps.
Roy
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Comments
Roy
Roy
I'm convinced it is not a problem with anything in the engine compartment. In an effort to isolate this thing after much testing we have brought in a known good 2005 with great brake pedal and moved the following parts from the known good unit to the bad one with no luck.
1. Vacuum pump
2. Vacuum booster
3. Vacuum check valve and hose
4. Master cylinder
5. ABS control valve
6. Bled multiple times
It has to be something in the base brake system which from the ABS valve back consists of nothing more than hard brake lines, rubber lines and calipers. The rubber lines have been physically inspected while brakes are being applied and they are not expanding at all. The last Daimler rep I spoke to Friday said he had seen this problem and it was a stuck caliper piston that was cocking in the housing and was not applying consistent pressure on the pads giving the pedal feel we are experiencing. We will be going into the calipers tomorrow. How many miles are on your unit? This one has 221,000. Maybe removing the calipers and seating the pistons with C clamps then testing pedal feel with the clamps in place to see if the pedal still falls would isolate the base brake system. At least it would take the wheel ends out of the picture. After that I think we will just burn it.
Take a rubber tipped blow gun and blow air backwards into the closed bleeder screws. I found one that was not leaking fluid externally but may be sucking air in. It would blow bubbles when air was applied. I will know more tomorrow when I get parts. Mine was right front.
Roy
P.S. Am having a problem with "high idle" function. Switch seems to have power to it (background light comes on) but no high idle. We observed a very light "thud" noise when turning the switch off after unsucessfully going into high idle....but now we don't hear anything when we turn it off. In trying to trace this "high idle" problem, AllData refers to a "Fuse Block 3" where fuse is located for this operation...But nowhere does it twell us where the heck "Fuse Block 3" is located!! Any help you can offer? Thanx again...Ken
The Sprinter manual says fuse block 2 & 3 are under the seat. Fuse block 1 is under the steering column. We do not have this feature on our units, sorry I cant be more help. The high idle connector pinouts are as follows:
Cavity 1 = gy/dg/rd Lamp driver
Cavity 3 = br/wt High idle on signal
Cavity 4 = br/wt High idle on signal
Cavity 7 = br Ground
Cavity 9 = bk/rd Fused optional equipment relay output
Hope this helps,
Roy
check the fuse 12 - 15 amp at fuse block 3
Check optional equip. fuse at battery dist. block hanging off the pos. post. should be fuse 2
send me a fax number and I will fax you a wiring diagram for it.
Things in this circuit:
1. Optional equipment relay
2. Fuse block 3
3. ECM
4. Daytime running lamps relay
5. High idle switch
I found my brake problem on this unit. The rear brake pads were worn at an angle. It seems the vendor that did the rear brakes for us a month or so ago left the springs off the outside of the calipers. The calipers were caulking sideways when applied and wearing the pads crooked. We noticed the springs missing when we did a PM on this truck and it seems the problem started shortly after the springs were reinstalled. I am assuming the pads after being worn crooked would caulk a little in the caliper when the brakes were applied and caused soft braking and a pedal that would continue to fall as the pad was continuously caulked sideways under increasing pressure. Check all your brake pads and caliper springs. New pads fixed the soft falling pedal problem.
Roy
Did you find your brake issue?
Roy
Any luck with your brake problem?
Roy
I know it is a powered antenna.
IT NEVER WAS FIXEd AFETR MANY ATTEMPTS.
Mine is heat related as it only happens in the summer when temps get above 75 or so. It almost killed me once as the ABS was not working and my brakes locked up on a wet road THANK GOD there was a median i could steer off into.
If the president at FREIGHTLINER HAD ANY BALLS he would contact me. I think i will go on an internet attack and tell the truth.There is an old saying." The truth Hurts."
Have you ever lost one of the brake springs on the rear calipers, found it missing and then replaced it without replacing the brake pads? I had one with a brake fade issue where the pedal would go to the floor. Ended up being tapered brake pads. The outer spring that keeps the caliper centered was lost on road and discovered missing while performing a PM inspection. We replaced the spring without replacing the pads as they were more than 75%. With the new spring installed again this held the caliper back in the proper position which now created a slight gap between the rotor and pad on one edge of the pad. When the brakes were applied now one edge of the pad would hit the rotor first and then due to the tapper in the pad the caliper would twist a bit before the other side of the pad would hit the rotor. This slight gap at the pad and rotor translated into almost a full stroke of the brake pedal in the cab. Driving with the spring missing created a scenario where the caliper would twist a bit when the brakes were applied which in turn wore the brake pads in such a manner that a slight tapper was created on the pads themselves. Replaced the pads with new and the pedal fade issue went away. Hope this helps. Roy
Hi Guys, this is big john, master mech my whole life, also federal aircraft & engine mech LIC1244403, PLEASE PLEASE listen to what I have discovered over the last 8 years with my sprinter 2500, Above you read my message with the dealer and factory rep, right now im running without the ABS, master dirct to wheels, remember every thing was replaced at dealer, I mean everything, boster, master, rotors, ABS ect, this is what I have come up with, First ooof all DO cut the rotors, first problem is rotors are too thin (NEW) they expand and contract, in the morning I have little or no brakes, pump 3 or four times and I have good pedal about 3/4 but as I start down the street vehicles feels like it will not stop, I ride the brake a little and then Im fine, have very good pedal and nice and sentisitive, away we go, great brakes as long as im in the city, now after drining on the highway for 10 or fifteen minutes pedal goes almost to ffflfoor but I stop OK, now I use my brake every 5 minutes to keep pedal up, I say the totors are the problem but theres nothing you can do about that, PS Ive had a prussur bleed since 1948, really works great. OPPS above DO NOT CUT THE ROTORS I hope Ive been of some help to you guys and if any one finds a cure Im willing to spent $5000 to have brakes same as my car. BIG JOHN
I hope my message was accepted big john
I forget to mention, last time I had all the wheels off I removed all anti squeal materal from rear of the pads, pads are straight, also power bleed, I now have 3/4 of a pedal but of course still fades BIG JOHN
HI GUYS, IVE SPOKE MY PEACE BUT I WANT TO LEAVE YOU WITH 1 THOUGHT, FIRST OF ALL THE MASTER CYLINDER IS TOO SMALL FOR A 6 PISTON SYSTEM, A LARGER DIAMETER WHOLD REALLY HELP THE PROBLEM , 2ND THE ROTORS ARE TOO THIN, EVEN THE FACTORY BULLETIN SAYS DO NOT CUT THE ROTORS, SO WERE STUCK, WHAT I DONT UNDERSTAND IS THAT SOME GUYS CLAIM THEY DONT HAVE ANY PROBLEMS WITH THEIR BRAKES//??????????????? BIG JOHN
I want to thank the guy who said push all th pistons in with C clamps then checg the pedal, I tryed every thing else, will try this to see outcome, Big John
Hi Guys, Big John her, also JAY, my 2005 has had 4 master cylinders, Im attemping to replace master with a 2010 master, only problem, wish me luck and Ill let you know the results, I still think the master is the problem, JOHN
Hi guys, well I finally made the cure, I installed a 2014 master cylinder on my 2005 sprinter diesel motor home, GREAT NEWS full pedal, nod creeping or pedal fading, happy as a pig in mud, all you have to do to remove booster, stand on end, drop master cylinder on top, observe space between master flange and booster surface, remove booster push rod and adjust for exact length, had to shorten about 3/16 inch, make sure you bleed properly, best result is power bleed. Really hope this helps all you guys, after 7 yearsIve accomplished what I set out to prove. BIG JOHN
Hi Guys, well I finally proved the problem on 2005 sprinter, replace the master cylinder with a 2014 cylinder, all you have to do is readjust the pushrod that goes into the master, took 9 years but I have a full pedal all the ttime, BIG JOHN
Hi guys, well as I said I installed a 2010-2014 master cylinder on my 2005 sprinter, drove about 1000 miles since I installed it, GREAT NEWS< i proved the dam master was the problem all the time, brakes are perfect, full pedal all the time, hope some of you guys will do ther same and dont keep it it to yourself, lets hear from you. BIG JOHN
Thanks
Peter
take care
I think the problem is that since everything is remanufactured by now, the caliper piston bores are slightly oversized (as well as the MC although shop claimed my 2nd one was new from Mercedes). Since there is no “room to spare” the slight extra fluid needed results in extra MC piston travel which we don’t have much of. With calipers blocked off I had full solid pedal. A recent shop mechanic (different shop) was working on something else and told me he remarked to himself as the pedal went down that it needed new front calipers. He claimed his boss had a good supplier and had calipers that would eliminate this. Maybe. The best solution is more fluid in the system.
P.S. Before doing this myself I had the Sprinter towed to Mercedes and told the service manager I expected that they would consult with the factory if necessary and get to the bottom of this. Three days and $100 later the diagnosis was that it needed a new master cylinder. NOT! I had explained to him that the MC on the truck came off of their parts shelf a few days previous so I didn’t bother to repeat myself. I just thanked them and nervously drove the truck home. After adjusting the booster pushrod and numerous bleeding attempts using various methods I have just enough pedal to get pressure up (have a gauge attached to one of the MC ports) and have been living with it.
Jvf1234
Anyhow I have a 2006 Sprinter that has a fading brake pedal. We put a 2014 master Cylinder on it Like big John said and t still fades. Before that all new calipers, pads and rotors, along with new fluid Power bleeding, regular bleeding. And we still have brake fad...I was hopping for big John to be right...Do'es ant one have the answer? My sprinter has 41,000 miles on it... Its a Road-trek RV
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https://www.yourmechanic.com/article/symptoms-of-a-bad-or-failing-brake-hose
And No .no fluid winding up on the ground .............Thanks try some more, but i want to hear from someone that fixed the same, no guessing .......Where's big John now?
The first thing that needs to be done here is figure out if there really is a problem or not. On some vehicles that have been discussed, it is quite likely that there was an undiagnosed issue. On many of the others, this might simply be that the vehicle behaves differently than what is expected. So first let's find out if there really is something wrong or not. Keep in mind if it is actually working correctly, or isn't broke you cannot "fix it."
So park the vehicle on a level surface, in park with the parking brake set and turn the engine off. Pump the brake pedal a number of times until the power brake booster is bled of vacuum. You will hear it draw air each time the pedal is pushed and the pedal will get increasing harder to push. Once that is done (about 5 to 7 pumps) let your foot off of the brake and wait ten seconds.
Now apply the pedal one time pushing with a moderate amount of force like you are climbing stairs. How far did the pedal go? Hold the pedal for about a minute or two, is it sinking? Now pump the pedal about 6 times at one to two pumps a second and hold the pedal again with the same force as you did previously. Again, how far did the pedal travel? Did it pump up? Is it the same place?
Release the pedal and wait five seconds and then apply it one more time. Again note, how far did it travel? Now without releasing the pedal, start the engine. The pedal will drift towards the floor as the vacuum booster helps you apply the brakes. How far did the pedal go now?
If the pedal doesn't sink with the engine not running, there are no leaks internally or externally. If the pedal doesn't pump up (travels to the same point every time without assist) then there is no excessive travel nor air in the system.
The pedal sinking with the engine running and boost applied is normal. Compare how far you can push the pedal at a stop with the engine running to how hard and far you push the pedal when driving and coming to a stop. You may find that if you attempt to push the pedal as far when you are driving compared to how far you push it sitting still that you would have locked up all of the brakes and forced it into antilock.
If you are not able to force an antilock system event with a panic stop attempt, then the investigation shifts to the brake pad material choice.
Uk( Wales) does know an good mechanic how too fix this ..! I’m desperate cuz it’s not safety too drive like this