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2002 W21210 E320T Brake pedal sticking

shadowandspace

New Member
Joined
Feb 8, 2011
Messages
9
Location
London
Car
1996 E220T
I have a lovely 2002 W210 E320T Elegance that I have just purchased. It is a single owner car that has only done 39k miles but sat around for the later stages of the previous careful ownership being turned over doing a few hundred miles per year. It was fully and regularly serviced and very well looked after.

But I have a problem with the brake pedal sticking intermittently since I purchased the car 5 weeks ago. For example I drove the car yesterday morning for 30 minutes with no issues. However after the car sat parked for 2 hours the brake pedal was sticking almost always during my return journey, needing me to gently flick it back up from underneath to release the pedal and the brakes. It doesn't seem to happen when the pedal is fully depressed and sometimes doing this releases the pedal after it sticks.

I have had the car into the garage to check the brakes with wheels off which were fine, and to a second garage to have the pedal itself disassembled and fully lubricated. Both have not solved the issue.

A third garage I have now spoken to test drove the car and the pedal sticking didn't happen during this. Their advice is to change the master and servo which is an expensive outlay and best done together to save on labour as the servo has to come out to get to the master.

My question to the forum is are there any other things to try and would anyone be able to advise on using second hard parts, which could bring the outlay down dramatically (the MB parts are around £850 for both items). Any advice on sourcing good quality parts would be really appreciated.
 
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These master cylinders seem to be good value:

 
These master cylinders seem to be good value:

That is really helpful thank you for posting this. Would anyone be prepared to advise on the quality of non MB brake components and are a good cost effective alternative?
 
That is really helpful thank you for posting this. Would anyone be prepared to advise on the quality of non MB brake components and are a good cost effective alternative?
Remember that MB does not make the brake components on their cars etc.
 
I have just driven the car this morning and the brake pedal is returning perfectly.
 
I have a lovely 2002 W210 E320T Elegance that I have just purchased. It is a single owner car that has only done 39k miles but sat around for the later stages of the previous careful ownership being turned over doing a few hundred miles per year. It was fully and regularly serviced and very well looked after.

But I have a problem with the brake pedal sticking intermittently since I purchased the car 5 weeks ago. For example I drove the car yesterday morning for 30 minutes with no issues. However after the car sat parked for 2 hours the brake pedal was sticking almost always during my return journey, needing me to gently flick it back up from underneath to release the pedal and the brakes. It doesn't seem to happen when the pedal is fully depressed and sometimes doing this releases the pedal after it sticks.

I have had the car into the garage to check the brakes with wheels off which were fine, and to a second garage to have the pedal itself disassembled and fully lubricated. Both have not solved the issue.

A third garage I have now spoken to test drove the car and the pedal sticking didn't happen during this. Their advice is to change the master and servo which is an expensive outlay and best done together to save on labour as the servo has to come out to get to the master.

My question to the forum is are there any other things to try and would anyone be able to advise on using second hard parts, which could bring the outlay down dramatically (the MB parts are around £850 for both items). Any advice on sourcing good quality parts would be really appreciated.
Hi , DSM 10000 hates me with avengancent but I agree with his comments.

Changing parts with out finding the route of your problem could be expensive and somewhat dangerous if the diagnosis is incorrect.

I would not use use non Mercedes parts on my car under any circumstances.
 
When it's playing up - what does the pedal feel like underfoot as the brakes are applied? Any sponginess or sinking feeling?
 
When it's playing up - what does the pedal feel like underfoot as the brakes are applied? Any sponginess or sinking feeling?
Hi when its playing up the braking system feels normal no sponginess or sinking. The pedal push is normal and they activate as they should, its just the pedal just doesn't spring back after pressing down. Thanks for your help.
 
Just to get the obvious but easily missed out of the way - there isn't a floor mat binding on the pedal is there? The first thing the garages will have done is removed the mat out of the way for access so if it is they won't have noticed.

When you release it with your foot - does it spring back up rapidly or slowly return?
 
Just to get the obvious but easily missed out of the way - there isn't a floor mat binding on the pedal is there? The first thing the garages will have done is removed the mat out of the way for access so if it is they won't have noticed.

When you release it with your foot - does it spring back up rapidly or slowly return?
Just to get the obvious but easily missed out of the way - there isn't a floor mat binding on the pedal is there? The first thing the garages will have done is removed the mat out of the way for access so if it is they won't have noticed.

When you release it with your foot - does it spring back up rapidly or slowly return?
When I release the pedal it springs back as it should. Also I should have noted the pedal doesn't tend to bind when fully depressed, normally only when partially depressed. There is a floor at but it is not catching.
 
When I release the pedal it springs back as it should. Also I should have noted the pedal doesn't tend to bind when fully depressed, normally only when partially depressed. There is a floor at but it is not catching.
I noticed that bit earlier and I'm slightly confused as you also imply a rock solid pedal (no sponginess or sinking) and I don't equate rock solid with variable travel.
To my mind, the pedal should go to the point where all travel within the system (ie, pads are in contact with discs) and from that point further pressure on the pedal only increases pressure in the fluid - not pedal travel (or only by an absolutely marginal amount).
On the other hand, if further pressure on the pedal increases both pressure and pedal travel then that could imply air and/or an internally collapsing flexible brake hose. Any air in this case may be trapped in the ABS unit via a leaking valve. Either could cause a slow returning pedal - but only if there's a long pedal due to air or ballooning flexible hoses.

A bit leftfield as a theory I know and possibly overly influenced by the problem with my brakes I'm trying to eradicate but as the only thing within a master cylinder that could stop it returning is a broken internal spring, it's nigh on impossible for (a broken spring) to be OK sometimes and not others. At this point, the garage diagnosis of free non-binding pedal includes the rod leading to the servo and as much of the servo that can be accessed externally presumably?

Summary: If there's any excessive pedal travel consider hose and/or trapped air in the ABS. If the pedal is rock solid, consider some stiction in the master cylinder or servo.
I can't think of any other cause.
 

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