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rockfish
05-27-2015, 08:23 PM
I bought my 2004 with 250K miles on it. I had to replace the rear caliper which had a frozen bleeder screw and then bled the brakes by pumping. When the van is turned off the brake pedal holds firm so I assume the master cylinder is OK. Start the engine and the pedal goes to the floor. Pump a few times and it will firm up but still slowly go to the floor with pressure. I checked the power booster check valve and it holds pressure. Vacuum to the valve seems good but I hear a slight hissing when the valve is connected to the booster. Is the power booster shot?

NelsonSprinter
05-28-2015, 04:24 AM
To my knowledge the brake lines cannot be bled of air by pumping, only a Star or DAD system can run the ABS pump for this process. You may have air in the lines still IMHO
Do a search for the service manual online here may confirm this

Cheyenne
05-28-2015, 06:57 AM
DON'T PANIC!!!!!

This is perfectly normal for a Sprinter!

I had exactly the same issue after changing my brake fluid last year and after first panicking I then read through previous posts and found this is perfectly normal behaviour for a Sprinter. As long as the pedal holds firm during a moderate stop on the road you will be fine.

Search the forum and I'm sure you'll find previous posts as I did.

Keith.

rockfish
05-28-2015, 01:53 PM
Thanks. I did read the DR's posts on brake pedal and tried his tests and I seem to pass. I just can't get by the fact that when turned off the pedal is solid and when running it will go to the floor under steady pressure. I think I may bleed one more time just for grins and then I need to try and figure out where the ticking sound that I hear in the front is coming from and I get an occasional clunk when going from reverse to forward as I hit the brakes (might be rear shoe adjustment or loose shoe). I thought the front click was power steering pump but it may be something in the front brake shoes. I bought the van on eBay sight unseen for $6300 with 245K on it. From what I've checked so far all the fluids were changed before the sale. I pulled the injector cover off and it the area is clean and looks like the injectors may have even been replaced. Found out it has a rebuilt turbo on it and a Jasper rebuilt tranny. All in all I guess the deal wasn't too bad. I've just finished converting it to an RV.

Throttlejockey
05-28-2015, 03:02 PM
Thanks. I did read the DR's posts on brake pedal and tried his tests and I seem to pass. I just can't get by the fact that when turned off the pedal is solid and when running it will go to the floor under steady pressure. I think I may bleed one more time just for grins and then I need to try and figure out where the ticking sound that I hear in the front is coming from and I get an occasional clunk when going from reverse to forward as I hit the brakes (might be rear shoe adjustment or loose shoe). I thought the front click was power steering pump but it may be something in the front brake shoes. I bought the van on eBay sight unseen for $6300 with 245K on it. From what I've checked so far all the fluids were changed before the sale. I pulled the injector cover off and it the area is clean and looks like the injectors may have even been replaced. Found out it has a rebuilt turbo on it and a Jasper rebuilt tranny. All in all I guess the deal wasn't too bad. I've just finished converting it to an RV.

I was getting a clunk in the front when stopping and starting. Turned out to be a ball joint.

Markthelark
05-29-2015, 06:24 AM
My 2003 2.2 doesn't have ABS , so yours might be the same.
I have same problem ;
The pedal doesn't "go to the floor" but is very soft. It stops ok but you do feel that it's not going too !!!!!!
I haven't yet done a brake bleed yet but was hoping it would cure the problem , will use 5.1 . Thought it could be old fluid with water/air in.
Have read loads on the interweb about this , many say it's "Normal" but I'am not so sure !
Also noticed that it's worse some days than others.

NORTON
05-29-2015, 01:37 PM
With my limited knowledge of hydraulic brakes they are meant to hold pressure with a solid pedal
Slowly going to the floor means a fluid leak which would be noticeable by lowering of fluid level in the master cylinder and visible leaks in the lines , calipers or rear of master cylinder.
If no leaks are evident it could be the seals within the master cylinder allowing fluid to bypass
With the engine running vacumm assist applies greater pressure

Markthelark
05-30-2015, 04:58 AM
With my limited knowledge of hydraulic brakes they are meant to hold pressure with a solid pedal
Slowly going to the floor means a fluid leak which would be noticeable by lowering of fluid level in the master cylinder and visible leaks in the lines , calipers or rear of master cylinder.
If no leaks are evident it could be the seals within the master cylinder allowing fluid to bypass
With the engine running vacumm assist applies greater pressure

This is my understanding too.
Water or air in the system will give a soft pedal as well.
There are no signs of leaks on my system anywhere.
The pedal does not go to the floor , just feels very "spongy" , but does work and stops ok.
Will be giving it a good going over shortly , new pads and bleed , will update post then.
If you Google the problem there are loads of people state the same , with others saying this is common to Sprinters.
BTW , passes UK MOT test ok. ( annual road worthy inspection ).

NORTON
05-30-2015, 11:10 AM
Another possible cause of a spongey pedal is deterioration of the rubber/ flexible hoses which swell under pressure. I had this on one of my motorcycles and cured with braided lines

ECU
05-30-2015, 02:42 PM
Nope. Just normal. A new master cylinder was on my list when I purchased mine used. Then I realized the behavior is quite normal and expected for this rig.

MercedesGenIn
05-30-2015, 09:41 PM
Hi there,
There are a couple of other areas to check if this creep is excessive, but it is normal as has been said earlier.

If the load compensator valve above the rear axle is seized (If fitted to US versions - is present on UK version) Problems here amplifies the poor pedal feel, as does worn or seized brake caliper slides on the rear.

Observe the rear calipers from under the vehicle with a good light and get an assistant to press the brake hard while you watch, if the assembly appears to bend or tilt over when pressure is applied, there is a good chance you have an issue with the slides. Once this is sorted and/or the compensator (if fitted) is free and easy you will be assured of the best 'pedal feel' you are going to get.

If you think you have a sinking pedal now, just wait until you start to 'bed in' a new set of front pads on old rotors !! :smirk:

Time to worry is when the pedal sinks with the engine not running (press pedal a couple of times to discharge the huge capacity vac servo) once this is done you should have a rock solid pedal that does not decend at all. If the pedal creeps under these conditions, then its likely your master seals are passing and need to be attended to.

Rare and not often the case is air trapped in the ABS block (possibly after major pipe replacement etc) this can be fun and usually the best way is several gravity bleeds at each of the outputs of the ABS block. A final pressure bleed usually finishes the job.

Hope that helps
All the best
Steve

rockfish
06-04-2015, 01:46 PM
I ended up replacing the front pads and rotors and rebleeding. Also, one of the lug nuts was the correct size but wrong taper (wasn't holding the wheel at all) which was causing my "clicking" sound in the front. The brakes are much improved with less pedal play. The check valve into the brake booster holds vacuum so I'm sure the master cylinder and vacuum are OK so it's on to the next project. 140 ft/lbs for the lug nuts is crazy.

p40murf
06-27-2015, 08:53 PM
It may be normal and expected for this rig, but how safe is it if a vehicle with good brakes makes a panic stop in front of you??? Mercedes should do better. Do their cars have trouble stopping? I think not.

chromisdesigns
06-27-2015, 10:00 PM
It may be normal and expected for this rig, but how safe is it if a vehicle with good brakes makes a panic stop in front of you??? Mercedes should do better. Do their cars have trouble stopping? I think not.

Sprinters panic stop just fine -- as I found out last year when some POS old Ford pulled out right in front of me on a 55 mph highway, and then promptly STALLED in a squealing locked-wheel skid. After I pulled over and started back to ream the driver a new one, I saw a puddle if gas and oil spreading out under the engine, which then caught fire !

Instant karma at work, I guess. Looked like the engine blew up, or threw some parts through the crankcase and fuel lines.