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  #1  
Old 02-02-2013, 08:45 PM
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240D changed clutch slave, now gears barely engage.

Ordered a clutch slave cylinder from Pelican for my 81 240D by vin #, pre filled it with fluid. It was a ***** to install, hard to hold it close into the mounting hole enough for the bolts to engage, but with the help of some longer bolts to draw it in which i then replaced with the right ones, got it.

Now the clutch pedal works too well. Seems a tad harder to push maybe. When it is all the way out, the gears are not quite to barely engaged, not driveable. It's as if the clutch pedal is partly pushed , but it isn't. Used to engage very well, about 1/2 - 3/4 up from the floor.

The rod length appeared identical.

What did i do wrong? Could there be too much brake fluid in the cylinder? When i was struggling to get the cylinder on, the rod might have been at an angle, hard to tell. that should make it shorter if anything, no?

The car has 95,000 miles on it, and the clutch worked perfectly as long as i kept brake fluid in the cylinder(had a leak).

Baffled and frustrated, spent many hours on this. have to take my mom to the dentist monday.
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  #2  
Old 02-02-2013, 09:08 PM
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if comparisons of each side by side were the same, I don't understand what could have changed... perhaps you got the throwout fork crooked? perhaps the pressure plate was failing, and now is damaged? maybe the fork got off it's mount ball and is sitting against the plate?
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  #3  
Old 02-02-2013, 09:15 PM
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To much fluid wouldn't be the problem and the push rod would be the same but I dont know if it could have got misaligned, never heard of that happening so the next thing would be bleeding the system, how did you do that?
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  #4  
Old 02-02-2013, 09:28 PM
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are you thinking air is holding the clutch engaged? I don't see that happening...
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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
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  #5  
Old 02-02-2013, 09:54 PM
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Yes you have air in the hydraulic lines. Air compresses rather than moving the slave cylinder.

Have someone push on the clutch pedal then open and close the slave cylinder bleeder to let out the air. Then and only then let off the clutch pedal. Repeat until you don't get any air out and the clutch should work.

Pumping is not the option you want to use. Keep the master cylinder fullish. .

If you let off the clutch with the bleed open you will suck air back in.

Hope you can get it to work. Have plenty of fresh brake fluid on hand before you start, It adsorbs water once open the air.
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  #6  
Old 02-02-2013, 10:08 PM
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Didn't Bleed it but...

I didn't bleed the cyl, 'cuz i figured it was pretty full from when i filled it, and figured any air would keep the clutch from disengaging the gears, not the opposite problem that i have.

Will definitely give that a try in the morning, but am not too hopeful that will help.

Is there something inside the clutch housing that the rod is supposed to connect with? If so it might have gone in crooked & not engaged correctly. I have this stupid haines manual that doesn't show squat.

I saw a reference somewhere as to different length of rods on those cylinders. A quick visual, they seemed the same, and i did give the friendly folks @ pelican my vin #. Could i have gotten the wrong unit & not noticed?

Thanx for the responses so far!
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  #7  
Old 02-02-2013, 10:16 PM
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Air can compress 15 times and only exert 300 psi.

Even a couple of bubbles can prevent operation in most any static hydraulic system .

Not to test this but if you were to open a bleed screw on a brake caliper pump the pedal once then close it. You won't have any brakes on the circuit.
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  #8  
Old 02-02-2013, 10:51 PM
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Let me get this straight. You have no problem putting the transmission into a gear, but when you let up on the clutch pedal, the clutch doesn't engage fully and slips, right?

The clue here seems to be that you had to use longer bolts to reach the holes when installing. This indicates to me that the rod was already contacting the fork before you even started to thread the bolts into their holes. This means that as you were tightening the bolts, pressure was being applied to the fork and disengaging the clutch as you tightened them. That's not supposed to happen. You shouldn't have to use longer bolts in order to pull the cylinder in close enough to put the originals in.

My feeling is that any excess fluid in the slave cylinder would be pushed out to the reservoir as you bolted it down (same as compressing a wheel cylinder when changing brake shoes), so I don't think that's it. I have to believe either the slave cylinder is the wrong part, or somehow the rod didn't engage the fork correctly when you were installing it (I don't see how).

Unfortunately, I don't see how you are going to get around pulling the new one back out to fix this. If/when you do, put the new one and the old one side-by-side to make sure they are exactly the same.
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  #9  
Old 02-02-2013, 11:02 PM
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Sounds like if there are 5 neutrals and the history given there is no release of the pressure plate. Then the rod is too long or wedged in somehow. At least a long rod can be shortened or replaced with the original part.

For some reason I was thinking that the transmission was hard to shift. only allowing one gear.



Quote:
Originally Posted by LoosBenz View Post
Let me get this straight. You have no problem putting the transmission into a gear, but when you let up on the clutch pedal, the clutch doesn't engage fully and slips, right?

The clue here seems to be that you had to use longer bolts to reach the holes when installing. This indicates to me that the rod was already contacting the fork before you even started to thread the bolts into their holes. This means that as you were tightening the bolts, pressure was being applied to the fork and disengaging the clutch as you tightened them. That's not supposed to happen. You shouldn't have to use longer bolts in order to pull the cylinder in close enough to put the originals in.

My feeling is that any excess fluid in the slave cylinder would be pushed out to the reservoir as you bolted it down (same as compressing a wheel cylinder when changing brake shoes), so I don't think that's it. I have to believe either the slave cylinder is the wrong part, or somehow the rod didn't engage the fork correctly when you were installing it (I don't see how).

Unfortunately, I don't see how you are going to get around pulling the new one back out to fix this. If/when you do, put the new one and the old one side-by-side to make sure they are exactly the same.
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Iseki Diesel

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  #10  
Old 02-02-2013, 11:09 PM
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sun tortise:

If loosbenz got the question right, you may be experiencing what a few others have, i.e., fluid is not flowing back up from the clutch master cylinder to the reservoir when the pedal is fully released (up). In that case there is a hydraulic lock in the system, which is holding the clutch partially released.

There are two possible causes: 1. the eccentric on the clutch M/C push rod is misadjusted. 2. the fluid return port in the clutch M/C is clogged with dirt.
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  #11  
Old 02-02-2013, 11:17 PM
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Thanks, it did seem like a heluva lot of resistance putting that sucker in, tho never having done it b4, had no basis for comparison. The pedal is noticeably stiffer too.

Is it supposed to be able to go right up against the hole with little resistance?

If it turns out the rod is too long, is there a preferred method of shortening it ? (put less viagra in the brake fluid?)

Can't be too much longer, a cursory (or should i say cussory) glance and they appeared about the same.

Can't wait til morning so i can get all greasy & pisssed off again!
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  #12  
Old 02-02-2013, 11:21 PM
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Quote:
Originally Posted by Frank Reiner View Post
sun tortise:

If loosbenz got the question right, you may be experiencing what a few others have, i.e., fluid is not flowing back up from the clutch master cylinder to the reservoir when the pedal is fully released (up). In that case there is a hydraulic lock in the system, which is holding the clutch partially released.

There are two possible causes: 1. the eccentric on the clutch M/C push rod is misadjusted. 2. the fluid return port in the clutch M/C is clogged with dirt.
If the fluid return port is blocked, he should be able to crack open the bleed screw, releasing the pressure and the fork should return to normal position, right? Not really a solution, but at least it would tell if it's a hydraulic issue.
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  #13  
Old 02-02-2013, 11:27 PM
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I rebuilt the hydraulic brake on my 75 RD 350
All three of the cylinders were frozen. I was able to put new pistons in wheel cylinder but the master cylinder was too corroded.

If your cylinders are nearly as frozen it may mean rebuilding or replacing the master cylinder.

Seems to me that the bleed port is only open when the master cylinder is fully retracted. Otherwise it would not be able to develop pressure.
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  #14  
Old 02-02-2013, 11:40 PM
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Did you bleed the clutch after installing the slave????

Just putting fluid in the slave and installing will not bleed the system.

99 to 1 there is an air pocket in the system. You will need to reverse bleed the clutch by connecting the clutch bleed screw to the brake caliper bleed screw then pump the brake peddle...and wait for the air bubbles to stop.

There is also a possibility the hose going from the reservoir to the master clutch cylinder is bad.

Pictorial here

Got a 1980 240D today.....
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  #15  
Old 02-03-2013, 12:52 AM
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Loos Benz:

Right On!

sun tortise:

Try the suggestion by Loos Benz.
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