Needing some help please - PeachParts Mercedes-Benz Forum

stcbenz83 · #1 06-13-2007, 01:42 AM

My problem just happened today. What happens is that the clutch pedal is getting lower and lower to the point now were it goes half way "free-falling" (like a loose pedal) with no feeling so to speak. Also now my grab point is extremely low. The clutch starts grabbing when im maybe a half inch off the floor. Before this happened, it use to half to go up halfway before it would grab. I looked at the master cylinder (which was replaced last year) and the slave, and both apear NOT to be leaking.....

So im in a bind. I use this car as my DD and the probelm seems to be getting worse, and fast.

Any input please on what the problem is or any ideas

thanks

stcbenz83 · #2 06-13-2007, 02:31 AM

Bump, Cause im real desperate

toomany MBZ · #3 06-13-2007, 03:38 AM

A friend has a '79 Euro CD with a manual, he has to bleed system every now and again. Has gotten good and fast, yet highly annoying. Sorry I can't help, other than sympathize. May have to spend the BUX.

stcbenz83 · #4 06-13-2007, 10:24 AM

and how do you bleed the clutch? hook a hose up to the front brake and slave cylinder?

why would this happen just allof a sudden?

Stevo · #5 06-13-2007, 10:34 AM

The first thing you need too do is go out and make sure the AFT section of the brake fluid reservoir has fluid in it. Its hard too see, look close. Then pull back the carpet under the brake & clutch pedal and reach up and feel the hard line that goes to the clutch master cylinder, is it wet? which would indicate a leak. look for brake fluid under the carpet also.

stcbenz83 · #6 06-13-2007, 10:40 AM

Quote:

Originally Posted by Stevo

The first thing you need too do is go out and make sure the AFT section of the brake fluid reservoir has fluid in it. Its hard too see, look close. Then pull back the carpet under the brake & clutch pedal and reach up and feel the hard line that goes to the clutch master cylinder, is it wet? which would indicate a leak. look for brake fluid under the carpet also.

checked brake fluid- was a little low and filled it. No leaks by the master or slave cylinders. carpet and floorboard is dry by the master cylinder.

MattBelliveau · #7 06-13-2007, 10:47 AM

How old is the clutch (plate, etc.)? I would check your slave cylinder again, for that's what it sound like to me. Could also just be your cable slipping (not sure if that's possible on these cars).

Matt L · #8 06-13-2007, 10:56 AM

Sounds like your master cylinder has given up. A bad master cylinder may not leak any fluid, but will often allow air in leading to exactly the behavior that you describe.

mbgizwiz · #9 06-13-2007, 11:01 AM

Sounds like an issue with the master, to me. There is a goofy adjustment on the link where the master cylinder rod connects to the clutch pedal. It is an eccentric pin, and it controls where the piston in the master cylinder rests in the bore at the "pedal up" position. If it is positioned such that the port to the reservoir is closed off, it can't get re-filled with fluid.
Since you had it replaced a while back, I suspect that the guy who did it did not get this adjustment right. It's kind of a peculiar thing to do, but not really hard, and should respond to a little trial and error.
Bleed it as well, of course. This is done at the slave.

stcbenz83 · #10 06-13-2007, 11:02 AM

MattB
I dont think these cars have cables as they are hydrolic, but im thinking it could be the slave cylinder.

the plate and disk are kinda old and are due for replacment by fall (although it does not slip yet) However for the car just to randomly do this, it leads me to believe that air is in the system

The master cylinder is only a year old.... could it go bad that fast?? ALso the clutch and everything were working fine before yesterday. THink a wrong adjustment could have something to do with it just randomly giving out?

thorsen · #11 06-13-2007, 11:11 AM

Hydraulic components can fail internally without a sign of external leakage. In other words, either the master or slave cylinder will not hold fluid pressure internally, but the external seals are fine.

If you don't want to replace/rebuild both, I would try to bleed the slave cylinder. If no fluid comes out, then suspect the master cylinder. If fluid comes out, then either the slave is shot, or the master cylinder is able to build a moderate amount of pressure, but not enough to actuate the clutch.

In my experience with hydraulic clutches, the slave is usually the first to go. If you can source rebuild kits, I would do both of them though.

Stevo · #12 06-13-2007, 11:16 AM

Quote:

Originally Posted by stcbenz83

MattB
I dont think these cars have cables as they are hydrolic, but im thinking it could be the slave cylinder.

the plate and disk are kinda old and are due for replacment by fall (although it does not slip yet) However for the car just to randomly do this, it leads me to believe that air is in the system

The master cylinder is only a year old.... could it go bad that fast?? ALso the clutch and everything were working fine before yesterday. THink a wrong adjustment could have something to do with it just randomly giving out?

You are correct, no cable and it wouldn't just "come out of adjustment" as with the eccentric and since you just had the master replaced, I'm guessing "slave", which is an easy replacement.

stcbenz83 · #13 06-13-2007, 11:30 AM

Yea i was thinking slave Cause i do hear that the slave is the first to go and since ive replaced my master before, but never my slave, im guessing that the problem.

It still holds enough pressure to be driveable (which i have to do today for work) but its really low and the grab point is very low also

Bleeding the slave, do you hook up a line going from the front brake to the slave cylinder and realese the bleeeding screw and remove the resivour cap to let the air escape?
-or-
What is the proper way to bleed the clutch, im sure ive done it before, but just making sure on the process

Stevo · #14 06-13-2007, 01:08 PM

One of the problems with this job is the bleed nipples of the clutch an brake slaves are different sizes. I use the clear hose from the hardware store that fits snugly on the brake slave, but will not be tight enough on the smaller clutch slave nipple. The solution is tiny hose clamps which can be easily tightened using the proper size 1/4" drive socket with a 12" extension. I have the car up on jack stands and I reach the brake pedal with my right hand and pump like crazy.

thorsen · #15 06-13-2007, 02:59 PM

Quote:

Originally Posted by stcbenz83

Bleeding the slave, do you hook up a line going from the front brake to the slave cylinder and realese the bleeeding screw and remove the resivour cap to let the air escape?

Nooooooooooooooooooo!

Have someone press on the brake, while you loosen the bleed valve on the slave cylinder. It is just like bleeding the brakes, but instead of stepping on the brake pedal and opening the bleeder valve on the brake, you step on the clutch pedal and open the bleeder valve on the slave cylinder.