Clutch Pedal not Returning

[Benz Dr.]

Originally Posted by KCM

Benz Dr., are you saying that the pedal should travel 20mm before engaging the master cylinder piston? I set the push rod so there is just a tad bit of free play and so the master cylinder piston retracts completely to allow the clutch and hydraulic pressure to push the pedal back and over center. Has worked for me (as long as there is no air in the system).

More like that distance before you feel any real resistance to movement. Some of that movement would include the free play at the pedal. Both the push pin on the MC and the slave cylinders need free play to perform properly. You won't need much but you will need some. Your system may adjust fifferently and 20mm is only a rough measurement.

[bhammontree]

Having a brake issue now with booster not working. Got to get that fixed first but will get on the clutch again as soon as I get the brakes sorted. I posted a separate issue on the brakes if anyone can help with that. Thanks. .

[aluminum]

Many times the Push Rod is the wrong one for for the Master cylinder
The Slash on the " eccentric bolt " Go's toward the "Rear " of the car as another poster stated . It is critical for the system to work correctly .

[optimusprime]

Must have a spring to return the clutch peddle . Also in the peddle box down in the foot well .

[bhammontree]

Still working on brakes, but the car does have return spring on the slave cylinder and a spring on the clutch pedal. Have adjusted the clutch pedal spring preset and it doesn’t seem to help. Will check the eccentric bolt and make sure I have it adjusted correctly. Thanks

[aluminum]

Originally Posted by bhammontree

Still working on brakes, but the car does have return spring on the slave cylinder and a spring on the clutch pedal. Have adjusted the clutch pedal spring preset and it doesn’t seem to help. Will check the eccentric bolt and make sure I have it adjusted correctly. Thanks

Mistake after thinking about it further the SLASH on the go's toward the REAR of the Car . The point being is to pull thee linkage all the way back so you have the correct FREE PLAY in the Master cylinder push rod

Also Make sure the . "eccentric bolt" is not to tight . If you tighten it a lot the Linkage well not allow it to return all the way so you need to have it only a little tight so that the linkage is free to return
I have had this problem before and what happens is that if not all the way released the system well build up pressure and the brakes well lock up
Perhaps as well the Clutch cylinder could do the same sort of thing build pressure

[bhammontree]

i finally got a chance to get back on the clutch problem while I am waiting on brake parts to come in. I bled it again with no improvement. I adjusted the eccentric bolt and put some grease on the pivot points in the pedal linkage and that helped it enough where the pedal would return some of the time, but not 100% of the time. It was acting like the rod on the slave cylinder was too short with too much free space to the clutch fork, and I had it adjusted all the way out. I finally took a bolt and made a slightly longer rod and adjusted it so that there was small amount of play to the clutch fork, and it worked! Not sure why I needed more adjustment on that rod, but the pedal is returning 100% of the time now.

[Idle]

Just a guess here, but could the rod from the slave cylinder have worn down over the years?

I can see where this could happen, but if the system was working before and then suddenly not it's not like you would 'suddenly' have worn down your cylinder rod.

[bhammontree]

I guess it is possible the rod might have worn down. This car was gifted to me after being in a barn 10+ years, and the clutch was not working when I got it. Over the last 2 months I have replaced every component in the clutch system (clutch disk, pressure plate, throw-out bearing, master, slave, hose between M/S, and now the slave cylinder rod. I was wondering if I might have gotten the wrong slave cylinder for this car somehow, and the travel on the cylinder is too short? I threw the old one away so can't compare them now. Anyway, it is working and shifting smooth now.

[dobrodan]

You, and others here, are not understanding the way the spring on the clucth pedal assembly is intended to work. The spring is meant to assist with pedal effort at the end of the travel, where the resisting force from the pressure plate is greatest. If the pedal does not return it is only because there is air in the line and it requires proper bleeding. I'm glad you finally got it bled, but you were able to do it because of the lack of free play in the rod. The only way to completely bleed these clutches is by taking out all of the free play in the slave cylinder rod and adjusting it after the clutch is operating correctly. The factory adjustments in the pedal assembly should never be messed with. These are things I learned as a factory trained MB mechanic working at a dealership when these cars were still coming in for service.

[bhammontree]

I think I understand how the spring is meant to work and adjusting it had no impact on the pedal returning. Also the slave cylinder rod was too short and it was not possible to take all of the free play out when bleeding it. I literally ran out of threads on the rod before the end made contact with the clutch fork. Fabricating a longer rod fixed the problem and it works fine now. I can’t say100% that there isn’t air in the line but I have bled this thing every way possible and it feels firm when pushing the pedal.

[bhammontree]

Also forgot to mention that I had to take the eccentric bolt out when I replaced the master cylinder. I’ve got it back in with the slash pointing to the rear and not too tight.

[aluminum]

Originally Posted by bhammontree

Also forgot to mention that I had to take the eccentric bolt out when I replaced the master cylinder. I’ve got it back in with the slash pointing to the rear and not too tight.

Its nice when it all works and works right finally

Good job