S204 Stiff Clutch and Intermittent Sticking

[JET1997]

Hi Everyone,

I recently purchased a 2011 C-Class S204 and I have noticed that it suffers from a very strange clutch issue.

The clutch pedal is very stiff/hard during normal driving and when i have been driving for long periods on the motorway (usually 30+ mins in 5th or 6th gear) i have found that when i come off onto the slipway and depress the clutch pedal that it is sometimes sticking to the floor. When this happens changing gear becomes very difficult but not impossible, however i can quite easily hook my foot under the pedal and lift it back up to its normal position which solves the issue and doesn't happen again until another long period of driving.

Currently i have replaced the slave cylinder and have also bled the clutch fluid but this has not fixed the issue.

Any thought on what could be causing this combination of issues?

My next port of call was maybe Master cylinder, beyond that maybe release bearing/clutch fork and lastly clutch/flywheel change

Thanks,
Josh - JET1997

 

[ChrisHGTV]

Strangely enough my Wifes Abarth had a pedal that would occasionally stick to the floor. I applied some silicone lubricant to the back of the master cylinder piston and it seems to have worked, which points to the master cylinder rather than anything at the other end. Might be worth trying the same in case it helps to identify whether its the master cylinder or not?

 

[Muckypaps]

Clutches, those were the days.

 

[JET1997]

Strangely enough my Wifes Abarth had a pedal that would occasionally stick to the floor. I applied some silicone lubricant to the back of the master cylinder piston and it seems to have worked, which points to the master cylinder rather than anything at the other end. Might be worth trying the same in case it helps to identify whether its the master cylinder or not?

thank you for the info, i will see if i can get down there and apply some silicone lubricant today/tomorrow to see if that helps. Master Cylinder was my next port of call anyway so would be good to get down there and have a look at it. Not sure whether that would also cause the clutch pedal to be as stiff as it is currently, which was why i thought there might be a deeper routed issue. My left leg is like a tree trunk now lol

 

[JET1997]

Clutches, those were the days.

i have just come from an auto (had it 2 years before someone wrote it off). Clutches have always caused me nothing but pain haha

 

[JET1997]

UPDATE

After attempting to lubricate the master cylinder, as recommended by ChrisHGTV, this unfortunately did not resolve the issue.

I have been moving home so have just been monitoring it for the last few weeks to get some more info, and i have noticed the following points:

- On warmer days the clutch appears to not be as stiff, more stiff during night time/cold weather
- Clutch pedal only seems to stick to the floor when the engine has reached temperature
- Clutch pedal will stick almost every single time after hard acceleration/high revs
- I have been able to feel when the clutch is going to stick as i can feel vibrations through the gear stick before depressing the clutch

Does anyone have any ideas as to what might be the cause with this extra info?

I am most likely going to change the master cylinder as that seems to be the main culprit for me.

Thanks,
Josh

 

[Tonygw]

This may seem odd and may or may not help. but the gearbox mount on these are prone to failure or wear. This causes the gearbox to rest on the gearbox mount subframe and vibration through the cabin. Its the same for both manual and auto and its an easy repair if you can get under the middle of the car to access it. Its a cheap part to replace (think I paid about £40 from autodoc)

If it fails badly it can put strain on the engine - gearbox and the engine mounts and may in some way affect the clutch. It may have no affect but worth looking into.

My thinking was that maybe if the extra strain may have a slight affect causing your issue? just a thought

 

[ernie]

This may seem odd and may or may not help. but the gearbox mount on these are prone to failure or wear. This causes the gearbox to rest on the gearbox mount subframe and vibration through the cabin. Its the same for both manual and auto and its an easy repair if you can get under the middle of the car to access it. Its a cheap part to replace (think I paid about £40 from autodoc)

If it fails badly it can put strain on the engine - gearbox and the engine mounts and may in some way affect the clutch. It may have no affect but worth looking into.

My thinking was that maybe if the extra strain may have a slight affect causing your issue? just a thought

Good suggestion...maybe trapping a flexible, so you force fluid one way, but not enough pressure for the return. Just a thought.

Ernie

 

[JET1997]

Thank you for your replies Tonygw and Ernie, i have just purchased a clutch master cylinder for £60 so i am going to replace that and also check out gearbox mount and flexibles while i'm down there. Will update here if it solves my issues.

Thanks,
Josh

 

[JET1997]

Post update:

The master cylinder has been changed - unfortunately still not change to the clutch. It is still sticking to the floor intermittently. The clutch is also still heavy, although it doesn’t feel as spongy and shifts a bit nicer, ever other issue still persists.

The gearbox mount was also checked and it is completely fine.

A friend had mentioned to me that I should check the clutch pressure valve (if my car has one)… does anyone know if these have them?

I guess the only other thing that could be causing the issue is the clutch itself??

Thanks,
Josh