w203 handbrake not working - mot fail

[leicschris]

Hi all

My 2003 c220cdi estate went for its mot yesterday and failed due to the parking brake not working.

The tester said the pedal went to the floor and stayed there even when the release handle was pulled.

He also said there was 0% effectiveness measured at the parking brake.

I never use the parking brake but did know that sometimes the rest warning light and sign came up on the dash and needed the pedal to be pulled up a little by hand to stop it but I thought it still physically worked, now I found out it doesnt

Any common causes as to what it might be

Thanks
Chris

 

[Stratman]

The first easy thing you can do is to lift up the rear seat base, then remove the panel underneath it. This will reveal the cable splitter, which joins the single cable from the pedal to the cable which goes to the parking brake actuators on the rear wheels, via a compensator.

While you're looking at it have someone operate the pedal. The main cable should pull on the lever and thus pull on the cable looped through the adjuster.

If that's working and the free play has barely been taken out using the adjuster, check behind the rear brakes for seized actuators and also for correct adjustment.

If the main cable doesn't move when the pedal is pressed down, it could have snapped or jumped out of the pedal.

 

[leicschris]

Hi

Thanks for the reply, and sorry for the time to respond.

I have had a look at the cable arm under the back seat and there was no movement at all when the pedal was pressed. For good measure I gave it a soaking in wd40 to help against any seizure.

I then looked further forward in the system and have found that the cable is not attached to the foot pedal and no sign of any plastic retaining clip.

I think I found where it should be attached to but as soon as I put it back and press the pedal the cable comes out again

I guess I need a new clip to hold the cable on the bracket?

Also, when the pedal is pressed it stays to the floor and pulling on the release handle does not bring the pedal back up again, is this due to the cable not being fitted or do I have another problem?

Thanks

Chris

 

[Stratman]

You'll definitely need a new clip.

Here's a picture of how things should be at the foot pedal. If it isn't returning when you pull the release lever it's very likely the spring has jumped out of the slot in the plastic lever, as shown in the second photo.

 

[leicschris]

Hi

I took the car into the college workshop today to try and sort out the handbrake as time is running out before mot retest time is up.

I got a new spring and plastic curved clip from the local merc dealers.

I am having problems with it, on that every time I put the handbrake cable into its holder on the foot pedal mechanism it jumps out again every time the pedal is released.

One of the mechanics at the college thinks there maybe should be a clip of some sort holding the cable in place but after phoning merc Leicester, the parts people say there isn't and the service team won't give any advice.

I checked the rear handbrake shoes and they are in a bad way and I now need to change them, and again the college tutor says this could cause the cable to jump out as it's at the end of adjustment on the thread but still too slack and when new shoes are fitted the cable should pull back?

Can anyone confirm how the cable should attach to the pedal mechanism and/or what may be wrong

Thanks

Chris

 

[Stratman]

Looking at this picture of my car, there does appear to be some sort of retainer preventing the end of the cable jumping out although as you say, correct adjustment should hold it in place more securely.

 

[leicschris]

Hi thanks for the picture

I found a rubber band type piece on the cable which might be what's showing in your picture, maybe the band goes over the end of the cable before going into the bracket thickening it so it doesn't jump out.

I'll try that and see if it helps, the Tudor also suggested a cable tie around the bracket to help stop if the cable jumping out. So maybe both will help.

Strange tho the epc doesn't show a clip of cable holder of any type

Chris

 

[Leabrooks]

Hi, I have a similar problem on my CLK, the spring keeps jumping out of the slot in the plastic lever (as shown in Stratman's pic) and I'm sick of keep putting it back in (the plastic lower edge of the lever is worn so it slips out when you depress the foot pedal on about every 5th application of the parking brake).
So does anyone know if the plastic lever and its retaining pin are available from an MB dealer? And if so can it be replaced in situ or does the entire pedal assembly need removing as I've heard it a major job to remove the carpeting in the foot well? Thanks

 

[Stratman]

I improved matters to a significant degree by putting a slight bend in the spring, towards the plastic lever, which holds it in rather better. The pedal still has occasional need of a helping foot to fully release, but it hasn't jumped out since I bent the spring.

My how-to on the parking brake issue

 

[BAZ-500SL]

I'm having trouble with my r129 I keep thinking it's just it being seized due to not getting driven much but now you guys have mentioned this I will have to give mine a look maybe there's a issue with my foot brake to

 

[Leabrooks]

Well I ended up removing the parking brake pedal assembly and modding the dam thing...4.5 hours later and in the darkness, job done. I'll try and write a guide when I have time on removal of the pedal assy and the mods I did (basically just a retainer to stop the main spring jumping out of the lever), its not hard but it is slow, no wonder they charge 3 hours labour. And yes i did it without stripping the centre console and half the dash, it can be done, you just need time, patience and a lamp/torch. Total cost for the fix (£1.17) !

 

[Stratman]

Looking forward to it.

 

[leicschris]

Hi

whilst I haven't fully sorted it, i managed to do a temporary bodge and pass the MOT retest today.

I put the cable back into the holder again only this time I put the end of the cable in the 'plastic band' and then put two cable ties around it to stop the cable jumping out again.

I took the car to the mot retest and it just passed, 17% efficiency against a min. level of 16%, which at least keeps the car legal and allows me to get xmas out of the way and fully sort it in January.

I'm also interested in the mod so I can do it in Jan along with new shoes, pads and disks.

Chris