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Clutch Problem - 1972 114 Coupe with transplanted M115 Engine
Hello Fellow Enthusiasts:
I have this particular clutch problem that has haunted me for over a year now... Problem: -Sinking Clutch Pedal (Sinks Halfway- returning) after less than 60 miles of last repair. Details: 1. Output Cyl (slave at bellhousing) is about 3 years old yet I had repaired via a repair kit about 3 times already. 2. Input Cylinder (master at pedal) after being repaired via kit twice, I decided to replace the whole assembly with a new one is 2 months old. 3. The 2 are always repaired in tandem. last repair was kit at output and new assembly replacement at input. 4. The pedal is Not hard to depress both immediately after being repaired and up to now (at least the 2nd half is still soft its just that the first half goes down with -very- little effort). 5. I can still shift gears. 6. 4 instances of repair from within 12 months. 7. Im afraid the pedal will go all the way down without returning while on a road trip. 8. No Vibration, dragging while at gear. 9. Slow return of clutch pedal when suddenly released 10. M115 Engine My theories: 1. Impending failure by the disk and pressure plate with Incidental failure of of input cylinders 2. Clogged pipes and hoses a. From Brake Master Cylinder reservoir or b.From the end of input Cylinder to the output cylinder. 3. Defective Brake Master Cylinder (internal Leaks) Any thoughts are welcome, welcome and welcome.. Thanks. |
#2
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My '60 Fintail clutch has occasionlly had similar behavior during the past two years.
My clutch components appear to be pretty vintage - as far as I can tell, they haven't been replaced in at least 10 years. I suspect an internal leak in the clutch master cylinder. Happy Motoring, Mark
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DrDKW |
#3
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This might sound obvious, but is clutch being properly bled in reverse..... say, pushing fluid up the slave cyl from running tube off L/F brake calipre to the clutch slave while pumping the brake pedal..... basically bleeding the clutch by forcing air bubbles up from the slave, through the master pedal cylinder into the reservoir.
And of course you are using DOT 4 fluid (or better) instead of DOT 3 which causes MB seals to leak...... Last edited by 300SDog; 01-13-2004 at 01:17 PM. |
#4
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I presume there's a flexible section of pipe in this set up (my 114 coupe was an auto, so I'm not familiar with the manual setup). If so, the flex pipe may be collapsing internally and acting as a partial one-way valve, preventing the pedal returning due to the fluid being restricted. The higher pressure of your foot on the pedal will open the pipe, but the lower pressure of the return spring just won't manage this.
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Cheers, Neil |
#5
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Agree with Neil, but you may have some roughness in one or both of the cylinders that is chewing up the seals progressively faster.
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Chuck Taylor Falls Church VA '66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe |
#6
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edited my post above to make it clearer.... must have been drinking at the time of writing it.
Otherwise, another thing to look for is drops of hydraulic fluid coming from the weep hole of the bell housing indicating yet another blown clutch slave cylinder. Also check the flexible hose lines of the hydraulic system for being porous and letting in air..... I've seen this problem on later 240D's. |
#7
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Is the system consuming fluid? If so, there may be an internal leak in the booster and fluid is being sucked into the intake manifold. This can be a scenario with disappearing brake fluid, but it may also affect the clutch fluid in that the systems are fed by the same reservoir?
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Douglas 1959 M-B 220S cabriolet |
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