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  #1  
Old 05-18-2004, 10:26 PM
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Location: Sydney, Australia
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Final chapter for 190E clutch saga (I hope)

Some of you may remember the problem with the clutch in my '90 190E-2.3 Sportline that became apparent just over a year ago. Initially I thought it needed a new clutch. See the original thread here 190E clutch replacement. Any tips?

Due to the intermittent nature of the problem I initially did nothing other than to think about it and raise the possibility of a hydraulic fault in this thread "High" clutch pedal problem. Any ideas?

Further investigation and discussion focusing on the master cylinder continued in this thread Clutch master cylinder question W201 & 124.

Yet more discussion and my findings following flushing and bleeding the clutch hydraulics can be found in a fourth thread I was hoping one of the MB techs had experienced this

Well, up until about a week ago, the clutch had been behaving itself. It had gone through the heat of summer without the earlier problem of a "heat soak" causing the clutch engagement point to progressively get higher in the pedal travel until slip occured. Presumably, the fluid flush had cleared debris blocking the master cylinder inlet port. Last week, while shifting gears, the clutch pedal went to the floor without disengaging the clutch (a problem reported here on many occasions). I could pull the pedal up and it would work a few times until again remaining on the floor without disengaging the clutch. It was now obvious that the master cylinder had worn out (no fluid loss was occuring eliminating the possibility of a slave cylinder fault).

I ordered a new master cylinder (which now carries a 202 part number and is manufactured from a hard plastic). Being a right-hand-drive car, the two securing nuts for the master cylinder were impossible to access, so, after draining the fluid reservoir, I removed the entire clutch and brake pedal assembly (not as difficult as it sounds).

With the new master cylinder fitted and the pedals re-installed, I re-filled the reservoir with the pedal assist spring holding the pedal at the floor. With the master cylinder inlet port at the top this allowed the cylinder to re-fill, effectively "self-bleeding". Since no air had entered the slave cylinder or the line between the master and slave, and the master cylinder virtually full of fluid, the remaining air bubbled back to the reservoir with a few pumps of the pedal. The clutch has been working perfectly since with good pedal feel and consistent clutch engagement point at the correct point in the pedal travel.

Thanks again to all those who followed and contributed to the lengthy saga. Hopefully this will be the end of it.
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107.023: 350SLC, 3-speed auto, icon gold, parchment MBtex (sold 2012 after 29 years ownership).
107.026: 500SLC, 4-speed auto, thistle green, green velour.
124.090: 300TE, 4-speed auto, arctic white, cream-beige MBtex.
201.028: 190E 2.3 Sportline, 5-speed manual, arctic white, blue leather.
201.028: 190E 2.3, 4-speed auto, blue-black, grey MBtex.
201.034: 190E 2.3-16, 5-speed manual, blue-black, black leather.
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  #2  
Old 05-18-2004, 11:59 PM
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Thanks for the update, Greg. In one of those threads I mentioned that my slave cylinder was probably going - clutch engagement is very low, but improves with use or pumping, and there is evidence that the slave is seeping.

Well I waited too long to change it, and last week the clutch was dragging and it would not pump up easily, so I parked it and brought my '91 MR2 out of storage. I did a 15K maintenance today, and will swap the slave tomorrow at a friend's house. For practice I tried to loosen the two mounting bolts and all it took was a 13mm combination wrench, but for the upper one I had to improvise an impact arrangement with a length of 2x2 and a hammer being as how I couldn't get enough leverage with my hand.

Removing the three screws that hold the heat shield so it can be moved out of the way was a great help.

I didn't try to loosen the hydraulic line as I do not have a 12mm tubing wrench, but my buddy does, so if I can get it loose without buggering the flats it should work out okay. On LH drive models there is a steel hydraulic line that loops over the gearbox to the connection to the hose on the LH side. According to the Haynes shop manual, RH models have a flex line to the slave, so you remove the flex line coupling upstream at the hard line and remove the slave with the hose attached. Looks like a slave change on the RH driver model may be easier than LH drive. Being as how most Mercs are sold in LH drive markets, I can't understand why they positioned the slave on the RH side!

If anyone has changed a slave on a LH drive 201 or 124 let me know if you have any helpful tips.

Once the clutch release situation is corrected my Merc goes into winter storage.

If the slave doesn't solve the problem, we'll be talking about the master cylinder change some more.

Duke
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  #3  
Old 05-19-2004, 08:15 AM
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Duke, did a slave recently on W124 (LH drive). Hydraulic line was removed from below with a crowfoot. Just had enough space for the extension (was still a little angled to the fitting). The 13mm bolts were attacked from behind the flex disc with a series of extensions. I found that bleeding was best done per the book, forcing fluid in to the slave cylinder, using the RF brake as a source (I don't have a pump). Of course, the brake and clutch bleeder screws are different diameters, so there was a bit of a mess. Hope this helps.
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  #4  
Old 05-19-2004, 09:54 AM
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Quote:
Originally posted by hanno
I found that bleeding was best done per the book, forcing fluid in to the slave cylinder, using the RF brake as a source (I don't have a pump).
Can you explain this in a little more detail. I've heard that bleeding can be a bear! My plan is to use a vacuum pump from the slave valve and try to get it mostly filled, then finish bleeding conventionally by pumping the pedal an opening the valve. Thanks for the tips.

Duke
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  #5  
Old 05-19-2004, 10:31 AM
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Greg in Oz, Did you say the clutch master was made out of plastic? That sounds scary.

I just changed my master in my left-hand-drive car (the new one was metal) and those two securing nuts for the master cylinder were still impossible to access. I took the pedal assy out too and I agree it isn't as hard as it sounds. The funny thing is now it doesn't come high enough to push the cruse control switch.

Bleeding can be successful any way you do it, I guess using a vacuum pump is as good a way as any, but the easiest way is to back bleed it through the slave. I used my compressor to force the fluid it and that worked quite nicely.

Duke2.6: did you mean you are going to put your car in winter storage in May?
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  #6  
Old 05-19-2004, 11:38 AM
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Quote:
Originally posted by Jim Anderson


Duke2.6: did you mean you are going to put your car in winter storage in May?
Summer storage! The 190 is my daily driver during the winter, and I use the '91 MR2 in the summer. The MR2 has never been on a wet road, and the Merc has been in the rain no more than twice in the last several years.

Being as how I'm retired, I only use the cars once a week or so and typically don't plan any driving when it rains - keeps the car clean underneath, and I don't run the risk or being bashed by dumb LA drivers in the rain!

When it rains in LA there are probably more accidents than a blizzard in Chicago!

Duke
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  #7  
Old 05-19-2004, 07:40 PM
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Jim,
Yes, it appears to be that brown-coloured, hard, "glass filled" type of plastic (excuse my ignorance, I'm no plastics expert). My attention was drawn to this by its light weight and non-metallic colour. I had to be extra careful when threading in the rigid line leading to the slave since it is so easy to cross-thread into plastic. Being plastic does sound scary but then I guess the seals are only soft anyway. The cylinder is a genuine item from my local dealership, obviously as fitted to the W202 C-class judging by the part number. The price of the new master cylinder (about AUD$115) was only slightly more expensive than a kit for the old one. It was also in stock in the country whereas a kit would have to come from Germany. No after-market suppliers here stocked a clutch master cylinder (obviously not much demand with relatively few manuals).

Duke,
I can imagine replacing the slave is tricky, especially if it has a rigid line leading up over the transmission. I did not have to get under mine this time but from memory it has a short flexible hose between the slave an the rigid line. The bleeding technique Hanno mentions is described in some workshop manuals (mine don't desribe it but a friend's earlier Haynes manual does). The technique is to connect a hose between the bleed nipple on the slave and the nipple on the front right brake caliper. Lossen the nipple on the slave and then using a two-man technique "bleed" the front right brake. This will force fluid from the brake caliper throught the hose into the slave. This forces air from the clutch slave back through the master and back to the common fluid reservoir. It was using this technique many months ago that I established that the inlet port to my old clutch master was blocked.

Greg
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107.023: 350SLC, 3-speed auto, icon gold, parchment MBtex (sold 2012 after 29 years ownership).
107.026: 500SLC, 4-speed auto, thistle green, green velour.
124.090: 300TE, 4-speed auto, arctic white, cream-beige MBtex.
201.028: 190E 2.3 Sportline, 5-speed manual, arctic white, blue leather.
201.028: 190E 2.3, 4-speed auto, blue-black, grey MBtex.
201.034: 190E 2.3-16, 5-speed manual, blue-black, black leather.
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  #8  
Old 10-26-2004, 02:36 AM
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After five months of faultless operation, this final chapter now has an epilogue!
See 190E Clutch Saga - Epilogue!
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107.023: 350SLC, 3-speed auto, icon gold, parchment MBtex (sold 2012 after 29 years ownership).
107.026: 500SLC, 4-speed auto, thistle green, green velour.
124.090: 300TE, 4-speed auto, arctic white, cream-beige MBtex.
201.028: 190E 2.3 Sportline, 5-speed manual, arctic white, blue leather.
201.028: 190E 2.3, 4-speed auto, blue-black, grey MBtex.
201.034: 190E 2.3-16, 5-speed manual, blue-black, black leather.
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  #9  
Old 12-13-2012, 12:10 PM
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FYI

Quote:
Originally Posted by Greg in Oz View Post
After five months of faultless operation, this final chapter now has an epilogue!
See 190E Clutch Saga - Epilogue! - PeachParts Mercedes ShopForum
This is why I have a shop rule.
If the clutch slave or master cylinder is bad, they are both replaced at the same time.

My Direct Experience over 35+ years:
If one has failed, the other (typically) will fail within one year.

.
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