W115: Clutch/ Master/ Slave Cylinder Rebuild Needed? - PeachParts Mercedes-Benz Forum

Screwdriva · #1 02-26-2020, 02:31 PM

Greetings!

As I drove home today, my clutch pedal didn't rise up to where it normally would be. The sinking feeling soon subsided and the ol' girl got me home safely (God bless Classic Mercs!).

That said, there is one other symptom: A rattling noise at idle. No, it's not the diesel idle clatter. It's a slightly louder, harsher sounding rattle that only occurs at idle. A light touch of the accelerator pedal or engaging the clutch pedal fully and the noise disappears, only to reappear when all feet are off all pedals again.

Perhaps its the thrust bearing?

At this stage, given the likely need to replace the master and slave cylinder, would it be prudent to replace the clutch (doesn't slip - car has plenty of pep) and bearing as well? If so, would the MB dealer be the best place to source the replacement components? Listing the time worn parts you believe are prudent to replace with the transmission dropped out of the car (with numbers if you have them handy) would be incredibly helpful and I would owe you one!

Cheers!

C.Doner · #2 02-26-2020, 03:17 PM

I dont think the rattle is a big issue. Is it a new noise? I would leave the clutch alone until obvious release bearing noise. Most MB manuals have that rattle in neutral. No need to be tempted by thicker oil IMO.

Screwdriva · #3 02-26-2020, 04:02 PM

To be honest, I'm not sure what the release bearing noise sounds like. This noise, has existed since the car's purchase.

If the clutch is to be left alone, I'm assuming the master/ slave cylinder replacement is more straightforward? I've never done this job.

Frank Reiner · #4 02-26-2020, 05:07 PM

Quote:

Originally Posted by Screwdriva

As I drove home today, my clutch pedal didn't rise up to where it normally would be.

Two things cause the clutch pedal to return:
1) The spring in the clutch pressure plate.
and
2) Once the pedal is about half way up, the over-center spring at the top of the pedal.

Screwdriva · #5 02-27-2020, 04:30 AM

It appears that hydraulics also play a role ...

https://forums.mercedesclub.org.uk/index.php?threads/w115-clutch-pedal-stuck.172167/page-2

Screwdriva · #6 03-03-2020, 05:40 AM

As a preventative measure, both rubber hoses and clutch cylinders on order from Mercedes. The rattle is the real worry but I'm hoping it's something less sinister than the release bearing.

t walgamuth · #7 03-03-2020, 06:22 AM

The standard transmission will rattle in neutral....that is normal.

Screwdriva · #8 03-12-2020, 05:37 PM

Interestingly, the rattle goes away with a 50 rpm throttle input and doesn't return when zero throttle inputs resume. It returns at the next stop light (or two).

The clutch pedal continues to fail to return fully but it does return to around 50% of its normal position.

t walgamuth · #9 03-13-2020, 04:01 PM

The clutch should come all up.