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  #1  
Old 09-14-2011, 11:15 PM
gastropodus's Avatar
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Location: Portland, OR
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W201 190D clutch question

OK, so I've been neglecting my Euro 190D with the 5 speed... too busy breaking in the 240D. Among other things I need to finish the delivery valve seals on the 190D. However, it was also starting to develop a clutch problem the last couple times I drove it. Here are the symptoms; maybe they will suggest to you whether it is a master cylinder problem, or a slave cylinder problem.

The problem: I noticed that if I sat at a red light, and kept my foot on the clutch (pressing it down), it would be impossible to shift. I found that if I pumped the clutch before attempting to shift at a red light, I could get into gear.

So, master cylinder? or slave? Or just do both, because it is going to be such a hassle to bleed the system that I shouldn't take the chance on the other one going out in a month.

Thanks for your opinion.

Kurt

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- '79 240D - engine swap complete! Engine broken in! 28-31 mpg! Lovin' the ride!
- '86 190D (W201-126) - 2.5 NA engine, 5 speed, cloth interior, manual climate controls, 33-34 mpg (sold to forum member).
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  #2  
Old 09-14-2011, 11:57 PM
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Location: Cape Cod Massachusetts
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Quote:
Originally Posted by gastropodus View Post
OK, so I've been neglecting my Euro 190D with the 5 speed... too busy breaking in the 240D. Among other things I need to finish the delivery valve seals on the 190D. However, it was also starting to develop a clutch problem the last couple times I drove it. Here are the symptoms; maybe they will suggest to you whether it is a master cylinder problem, or a slave cylinder problem.
Quote:
Originally Posted by gastropodus View Post

The problem: I noticed that if I sat at a red light, and kept my foot on the clutch (pressing it down), it would be impossible to shift. I found that if I pumped the clutch before attempting to shift at a red light, I could get into gear.

So, master cylinder? or slave? Or just do both, because it is going to be such a hassle to bleed the system that I shouldn't take the chance on the other one going out in a month.

Thanks for your opinion.

Kurt


When you say "impossible to shift" do you mean smoothly without grinding gears etc.?
Because you should be able to shift gears without using the clutch if you just forced the shifter to move position. At least it would pop out of the gear it was in even if it couldn't easily shift into another gear.


So assuming that what you mean is you aren't able to shift using the clutch as you had been able to in the past the thing to do is verify that there is no leaking of hydraulic fluid at the slave out its front seal, its bleeder, or line connection; as long as there was no apparent issue there it would have to be the master cylinder leaking pressure past its seals back towards the reservoir. The loss of pressure allows the slave operating rod to retract re-engaging the clutch preventing shifting in the clutch dis-engaged (normal) mode.

Repair (rebuild) or replacement of the master cylinder should restore function. Some folks have reported the subsequent failure of the slave after doing that ascribing to the theory a better functioning master causes elevated pressure stressing and causing the failure of an older worn slave. Might be true.

As you would in any case need to get under the car and screw with the slave in order to bleed the system it seems like a fair judgment call to replace the slave while you're under there and bleeding anyway rather than repeating the process a couple weeks or months later.

As for bleeding the clutch system it is often extremely difficult if not virtually impossible to do so by any means other than bottom up. The easiest method is to use a cheap pump style oil can to push brake fluid into the slave bleeder and up through the system to the reservoir. If you do a search I think there is a thread mentioning this method with some pictures on the forum.


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  #3  
Old 09-15-2011, 12:27 AM
gastropodus's Avatar
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Clarification: what I meant by impossible to shift was that it resisted movement from wherever the shift lever was. So if I had pushed in the clutch while in third gear, and then sat at the stop light in third with the clutch down, it would not come out of third into the neutral position (the time that happened I had to kill the engine, pump the clutch, move it into neutral, and re-start). More often, I would sit at the light in neutral with the clutch pedal down (bad habit, I know) and I couldn't move into first to get going unless I pumped it.

Thank you for your advice. Guess I better price 'em both.

Kurt
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- '79 240D - engine swap complete! Engine broken in! 28-31 mpg! Lovin' the ride!
- '86 190D (W201-126) - 2.5 NA engine, 5 speed, cloth interior, manual climate controls, 33-34 mpg (sold to forum member).
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  #4  
Old 09-15-2011, 12:45 AM
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Join Date: Nov 2001
Location: Cape Cod Massachusetts
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Quote:
Originally Posted by gastropodus View Post
Clarification: what I meant by impossible to shift was that it resisted movement from wherever the shift lever was. So if I had pushed in the clutch while in third gear, and then sat at the stop light in third with the clutch down, it would not come out of third into the neutral position (the time that happened I had to kill the engine, pump the clutch, move it into neutral, and re-start). More often, I would sit at the light in neutral with the clutch pedal down (bad habit, I know) and I couldn't move into first to get going unless I pumped it.

Thank you for your advice. Guess I better price 'em both.

Kurt
Yeah, I was just trying to clarify whether there was a direct connection between cluth function/non-function and the ability to move the tranny's gears with the shift lever. There are situations where the ability to move the gears could be internal to the tranny itself, improper fluid, worn syncros, etc. or even external such a problem with the shifter, its rods or the bushings on the arms or rods.

If your moving in and out of gears problem coincides with the clutch pedal malfunction then the hydraulic system seems to be the most likely culprit.
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  #5  
Old 09-15-2011, 11:12 AM
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Check the rubber hose inbetween master and slave first. I had one that was seeping under pressure. Cheap fix.
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  #6  
Old 09-15-2011, 11:25 AM
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Check your floormats

If the master is leaking out there will be wet spots in the drivers footwell. The mentioned oil can bleeding is promising, the other way is to bleed using the front caliper bleeder screw to force fluid and air bubbles up through the slave into the master and ultiimatley the reservoir. While you are under the car you should check the clutch disc wear using the little forked shim thingy into the slot in front of the slave cylinder face. Cheers Dan

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