clutch master cylinder assembly install going haywire

Lee Iaccoca · 02-07-2008, 06:19 PM

I recently got the clutch master cylinder assembly I ordered for my 94 YJ.

Pretty straight forward I thought: Slide the pin off the clutch pedal, unscrew the old master cylinder from the fire wall, unscrew the other end of the existing assembly from the transmission and wind the whole assembly out of the engine bay.

Then get the other assembly, which is already prefilled, and simply do the "removal" in reverse, so to speak. Great, so brand new assembly and everything's good after I installed it, right? Nah!

Well I check the new resevoir to make sure the fluid is topped off. Then I start pumping the clutch pedal. It goes right to the floor. I pump the thing 100 times, nothing. I check the master cylinder resevoir in the engine bay, check for leaks...nothing.

So I Get under the jeep, check where the assembly mounts to the transmission (I'll just call this the "lower assembly" from here on). Then I decide to just unscrew the lower assembly from its port on the tranny to make sure the components on that end are ok.

Here's where I find the problem: I get the thing off and the piston had basically popped off and fluid was leaking all over the place. I slide the "lower assembly" out and see that everythng on that end had basically come apart, the spring was out, the rubber cap was off, etc.

I put everything back together in the "lower assembly" and, this time, make sure the piston seems to be contacting what I thought was the target spot in the metal port: this little concave metal surface you feel if you stick your finger inside. So I make sure that there seems to be a connection, I force the spring to compress, hold it down and then bolt the lower assembly back on. I am figuring I've got it right this second time around.

So, I get back up, check the master cylinder assembly resevoir, top it off. Then get back in the driver's seat and start pumping the clutch. Again, nothing. Same as before and the 5spd just moves through the gears without me even engaging the clutch pedal.

You guys have any tips, any thing that I should be doing? This isn't working like I expected it would. Must be doing or did something wrong.

will_982 · 02-07-2008, 08:26 PM

You need to bleed the lines, I read your post and didn't see anything about it. A buddy has one of these bleeders http://www.trackhaus.com/motive-power-bleeders-c-65.html works great for the clutch but I just use my compressor, 2x4 and a old innertube to do my brakes (long story)

89jeep2 · 02-07-2008, 08:36 PM

Wait, what fell apart? The master cylinder is sealed, it can't just fall apart. When you say lower assembly, are you talking about the connection at the tranny. There isn't any reason to be near the tranny. There is a connection on top of the master cylinder.

Have you tried bleeding the system, you may have some air in the system causing the pedal to go directly to the floor. The bleeder valve is down by the tranny, drivers side or passenger side, depending on tranny.

Good luck.

SonofSam02 · 02-07-2008, 08:43 PM

hes got a 94
the lower thing he speaks of is the slave cylinder
i beleive that on the sealed ones, there is no bleeder
though someone else should chime in
You may need to take it back unless you can get it to gravity bleed.

pat8942 · 02-07-2008, 08:48 PM

Yeah it sounds like somthing is wrong.
If the slave blew it's innereds out than it's junk.
If it was seated on the fork than it had to be defective.
You won't have any luck bleeding because you can't just stuff everything back in and fix it.
This is just speculation but since you put the master (Top Part) on first you may have accidently pushed the clutch pedal after that.
Was that white plastic thing broken on the bottom part (Slave Cylinder)?

Quote:

Originally Posted by SonofSam02

hes got a 94
the lower thing he speaks of is the slave cylinder
i beleive that on the sealed ones, there is no bleeder
though someone else should chime in
You may need to take it back unless you can get it to gravity bleed.

Lee Iaccoca · 02-07-2008, 11:05 PM

Quote:

Originally Posted by pat8942

Yeah it sounds like somthing is wrong.
If the slave blew it's innereds out than it's junk.
If it was seated on the fork than it had to be defective.
You won't have any luck bleeding because you can't just stuff everything back in and fix it.
This is just speculation but since you put the master (Top Part) on first you may have accidently pushed the clutch pedal after that.
Was that white plastic thing broken on the bottom part (Slave Cylinder)?

Funny you should mention the white plastic thing. Yeah, this actually was broken. I, uh, broke it...

I had a good, though misguided reason: the slave assembly I was removing had the same plastic strips on the piston cap removed. I figured that the removal of the white plastic strips allowed the piston to extend fully and that this was a part of the installation process. I think this poorly-informed decision has forced me to buy another clutch assembly.

pat8942 · 02-08-2008, 08:59 AM

You're supposed to leave the plastic thing on while you install it and the first time you use the clutch it breaks.
That's how it's supposed to be.
When you get another one leave this on and install the Slave (Bottom part) first.

Quote:

Originally Posted by Lee Iaccoca

Funny you should mention the white plastic thing. Yeah, this actually was broken. I, uh, broke it...

I had a good, though misguided reason: the slave assembly I was removing had the same plastic strips on the piston cap removed. I figured that the removal of the white plastic strips allowed the piston to extend fully and that this was a part of the installation process. I think this poorly-informed decision has forced me to buy another clutch assembly.

SonofSam02 · 02-08-2008, 09:10 AM

How much is the slave/master cylinder that you got?

leedurr · 02-08-2008, 09:24 PM

Take it back and get a new one. Once you blow that slave apart it will continue to leak and never work right. Tell them it was afu from the box.

Lee Iaccoca · 02-09-2008, 04:12 AM

This go around, I'll take the hit on it (maybe it'll save me money down the road: I'll do my "homework" before making a poorly-informed, $/time-costly move like I did this time).

So I install the next one, right? What's the step-by-step procedure so this doesn't happen again? Maybe something like this:

1. Remove pedal pin, then Loosen remove old assembly - master and slave.
2. Bolt in new master assembly, work hydraulic line in to place, bolt in new slave assembly to transmission.
(this slave assembly having a white plastic strip on the piston cap that is in one piece)
3. Reattach pin to pedal.
4. Pump pedal until pressure builds in the line and white plastic strip "snaps" in the slave assembly.
5. Install complete. (?)

Does this sound about right? Thanks to guys here for the advice on this

pat8942 · 02-09-2008, 08:57 AM

That sounds right, After the first normal push on the pedal you should be good to go.
Let us know how you made out.

Quote:

Originally Posted by Lee Iaccoca

This go around, I'll take the hit on it (maybe it'll save me money down the road: I'll do my "homework" before making a poorly-informed, $/time-costly move like I did this time).

So I install the next one, right? What's the step-by-step procedure so this doesn't happen again? Maybe something like this:

1. Remove pedal pin, then Loosen remove old assembly - master and slave.
2. Bolt in new master assembly, work hydraulic line in to place, bolt in new slave assembly to transmission.
(this slave assembly having a white plastic strip on the piston cap that is in one piece)
3. Reattach pin to pedal.
4. Pump pedal until pressure builds in the line and white plastic strip "snaps" in the slave assembly.
5. Install complete. (?)

Does this sound about right? Thanks to guys here for the advice on this

TimsJeep · 02-09-2008, 04:51 PM

pat8942 is right - pumping the clutch pedal isn't part of the process. First time the pedal is depressed the shipping retainer on the slave cylinder will release and your good to go.

Lee Iaccoca · 02-16-2008, 06:27 PM

I managed to get these second assembly I ordered installed a few days ago.

A buddy of mine sent me the pdf install step-by-step from a service manual. It needs a line in there to the effect of: "Whatever you do, don't harm the plastic strips on the slave piston cap prior to installation ...It doesn't matter if it looks like somebody cut the ones on the piston cap from the old slave cylinder you are removing."

Much thanks for the advice given here on this!

rob1208lv · 04-15-2009, 10:54 AM

Quote:

Originally Posted by Lee Iaccoca

I managed to get these second assembly I ordered installed a few days ago.

A buddy of mine sent me the pdf install step-by-step from a service manual. It needs a line in there to the effect of: "Whatever you do, don't harm the plastic strips on the slave piston cap prior to installation ...It doesn't matter if it looks like somebody cut the ones on the piston cap from the old slave cylinder you are removing."

Much thanks for the advice given here on this!

do you still have the pdf of how to do this?? I have a 95 with a bad master and thought I would just change the whole assembly (slave and master)

Schoenberg · 04-24-2010, 03:26 PM

I broke the plastic strip and then installed the cylinder and it did the same thing. I fixed the situation by pulling the slave out and had my wife make sure the resevoir stayed full while I rammed the piston in and out. This effectively bench bled the slave while it was still under the jeep. No problems to the date.

02-09-2008, 04:51 PM	#12
TimsJeep Registered User Join Date: Mar 2003 Posts: 98 Profile Gallery Classifieds My Jeeps	pat8942 is right - pumping the clutch pedal isn't part of the process. First time the pedal is depressed the shipping retainer on the slave cylinder will release and your good to go.

04-24-2010, 03:26 PM	#15
Schoenberg Registered User Join Date: Apr 2010 Location: Springfield Posts: 1 Profile Gallery Classifieds My Jeeps	I broke the plastic strip and then installed the cylinder and it did the same thing. I fixed the situation by pulling the slave out and had my wife make sure the resevoir stayed full while I rammed the piston in and out. This effectively bench bled the slave while it was still under the jeep. No problems to the date.