Clutch Master Cylinders

[RKTJeep]

Over the last couple years I've had issues with clutch MCs developing leaks from the piston. This causes fluid to leak past the interior boot and down onto the fuse panel. I've pulled the boot back to verify that it is coming from the location.

 

I've tried Dorman, O'Reilly store brand, Advance store brand, and all look to be manufactured the same. All development this leak imediately or soon after installation.

 

I do a gravity fill with the bleeder open. Then once it's mostly blead and filled I do the traditional 2 person bleed method.

 

I'm posting this because my current one is starting to leak and I'm looking for more options and to see if others have had the same experience. It looks like LUK offers a MC for about $20 more than the "house brands" i may give it a try if no one has recommendations or solutions based on experience.

[cruiser54]

The one I got for my 86 was made in Italy. Maybe that's the LUK?

[RKTJeep]

Just wanted to follow up. I ordered the Luk branded MC and it is notably different from all others. The housing is cast steel and painted black, instead of aluminum. Dimensionally it is the same. So far I've had no issues with leakage and actuation is smooth.

[Jeep Driver]

47 minutes ago, RKTJeep said:

The housing is cast steel and painted black, instead of aluminum

Got a part number and source?

[schardein]

There was a guy that used to write articles for Four Wheeler magazine, Willie Worthy, I believe.  I recall an article where he mentioned that Jeep clutch MCs seemed to do much better with a specific brand of fluid.  The brand was Girling, I think.  Maybe I should start going through my vintage collection of Four Wheeler mags.

 

Along those lines, I wonder if using a DOT 5 fluid (silicone) would make any difference?  Both the slave and master would have to be replaced to start using it.

 

Another thing I have noticed.  Vehicles I have worked on that have a mechanical clutch linkage have a positive stop for the pedal, when it is in the "up" position.  Vehicles with a hydraulic clutch do not.  I recently did some work on the pedal hanger & pedal on my CJ7 which has been converted to a hydraulic clutch setup using CJ/YJ factory parts.  I don't know if it's needed, but I added a positive stop for the pedal.  Once when I was driving, when I released the clutch pedal, the rod from the pedal to the MC popped out the back of the MC.  I had to pull over, shut down, and put it back in place.  I replaced the MC and never had it happen again.  But now, with the positive stop, it can't happen.

 

Is your truck originally manual, or was it swapped at one point?  Perhaps the linkage is wrong somehow, leading to the failures.

[cruiser54]

That's the early XJs and MJs that used the British cylinders.

Another bit of info:

The rubber line from the master to slave deteriorated internally due to the wrong fluid being in the British system. You could replace masters and slaves quite a few times and  have them go bad because of the abrasive crap that developed in that hose.

 

Once they went to the Japanese cylinders, all was fine. 

 

Ya know, if folks bled their clutch fluid every 30,000 miles along with their brake fluid, those components would live longer lives.