Master Cylinder Problem

[scottsxj]

ok so i go to start the jeep this morning. It starts up just fine but i notice that the clutch has just about no pressure. So i check the master cylinder to make sure there is fluid in it, it was low but its been leaking for a while so i just poured in some more fluid. and try it again. Still no preesure and when i try to put it in reverse it grinds. Could some one please tell me whats wrong. Im thinkiing i need a new master cylinder ,but was curious if there was some other stuff that might be done before spending money on that. Thanks for any input.
scott

 

[Eagle]

For starters, you didn't tell us what year XJ, but in general there are three components to the clutch hydraulics, and your problem could be any one of the three: the master cylinder, the slave cylinder, or the line connecting the master to the slave.

Step #1 is to determine where the fluid is going. Check inside the passenger compartment, where the peddle rod goes through the firewall. If there's brake fluid dripping in there, the problem is likely the master cylinder (and should be repaired quickly, before the brake/clutch fluid destroys the fuse panel).

If there's fluid dripping out of the bell housing (if you have the internal slave) or off the slave cylinder housing (if you have the external slave), the problem is the slave cylinder. If you have fluid running down along the line/hose from the master cylinder, the problem is probably the line or hose.

 

[jneary]

i cant recall but i think the 92 still has internal slave cyl. its probably leaking(common problem) the system doesnt hold much fluid so it doesnt take much of a leak to get air in the system. bleeding it is a temporary fix.

 

[scottsxj]

I have a 92. and yes it has the internal slave. It was replaced not even a month ago. ill check that other stuiff when its light out, but i sure dont want to pull the transmission again. Thanks

 

[jneary]

make sure also that fluid isnt leaking where the master cyl comes through the firewall under the dash. if not maybe the system wasnt bled out all the way.

 

[scottsxj]

i know your are a mechanic so you know more than me but if it werent bled properly the last time, then why am i just now experiencing this problem, why not right after i put the clutch and slave in. Thanks again

 

[jneary]

you pobably have another leak, did you check the back of the master cyl of the fitting on the slave cyl for a leak. if it was bled right initially, and probably was if the clutch worked for a while, then something is leaking if you added fluid.

 

[Eagle]

i know your are a mechanic so you know more than me but if it werent bled properly the last time, then why am i just now experiencing this problem, why not right after i put the clutch and slave in. Thanks again

Back up half a step. Your initial post said it has been leaking for awhile, yet you then said the slave cylinder was replaced recently. What are your indications that you have a leak? Have you seen fluid on the ground or on any part of the vehicle that you know is clutch fluid, or have you just been noticing the fluid level going down in the master cylinder?

The clutch is a bear to get bled right. It's possible you had some air trapped in the system that allowed the clutch to function, but finally found its way up to the master cylinder and that's what caused the fluid drop. If that's the problem, one more bleed should do it ... unless you got air into it when it ran low, in which case you're back to square one.

If bleeding doesn't provide a long term solution, you're back to basics ... there are three parts to the system, and any one of them could leak. If your new slave cylinder is aftermarket rather than OEM, the fact it is new does not help much because aftermarket clutch hydraulics have a reputation for premature failure. Clutch stuff is one area where it is DEFINITELY worth the extra dollars to buy OEM Jeep parts. Examine the system, find where the fluid is, and replace the suspect part.

 

[Yucca-Man]

If your new slave cylinder is aftermarket rather than OEM, the fact it is new does not help much because aftermarket clutch hydraulics have a reputation for premature failure. Clutch stuff is one area where it is DEFINITELY worth the extra dollars to buy OEM Jeep parts.

I'll second that - after spending quite too much money replacing master and slave cylinders with aftermarket JUNK several times. Finally fixed it after the parts store let on that they had almost a 99% return rate over the past year.

 

[wascobi]

are we talking about raybestos stuff here? I replaced all three items on my '90 with their brand. right now I have no fluid leak, but no pressure till the bottom of the pedal! almost 2" of free travel on the pedal. how can air leak in if no fluid is leaking out? I've bled it out several times and even forced it up from the slave to the master. I think the piston in the master is just flopping around, but why is there no leaking? I hate my jeep today...

 

[wascobi]

no one else? wonder if a TJ clutch master will fit? dozens in the local jeep wrecker. any experience on this? :canada:

 

[jneary]

if you buy a used unit, that you dont know how long it has been sitting, and that fails, you will have to replace it again. why not spend a little extra and get a new one, and do the job once.

 

[wascobi]

I only got a year and a half out of my $180 raybestos m/c. if a tj will fit i'd rather spend $10 a year on a used yearly roplacement!

 

[old_man]

If you can do some basic fabing, I ran a Howes master cylinder on my XJ and loved it. The OEM units leak after a while and are a pain. The Howes has a stainless steel lined bore and you can even get a rebuild kit for it. They run less than $60. You will want the .75" bore. The mod consists of taking the old clutch rod out of the old MC, brazing it to a coupling nut and screwing it onto the threaded ron on the new MC. This gives you an adjustable clutch as well.

LOL

 

[wascobi]

hhmmm... where does one find one of these howes master cylinders? are they generic or application specific? you have got my attention!

 

[wascobi]

been to their site www howeracing.com did you get the girling style or the larger square metal res. type? the girling is not stainless lined, just the larger one. and if it was the larger one did you have any clearance problems? I'll be putting one in a '90 if it fits. I'll read all the info you can give us so dont be shy!
thanks, scott

 

[old_man]

I used the unit with the built in resivoir (sp?). I filed the seam above the MC just a touch to clear, but not much. The bolt spacing was the same.

Here is a pix

You can see how I took the old MC rod, cut it down, filed the end so it could fit in a coupling nut. I then brazed it. When I threaded it on the MC shaft, I used a jamb nut.

 

[wascobi]

I ordered mine this morning. $65 plus shipping. looking forward to having full pedal travel by next week!

 

[wascobi]

well, my howes m/c should be here any day! be nice to shift gears again instead of grinding them. old man, what type of line did you use to plumb it? I was going to try to make up an adapter to the existing line seeing as its new, but I think a new braided stainless line would be trick. is there an over-the-counter line available? sometimes it nice to just bolt-in, instead of searching and fabbing.

 

[dachner]

sorry if this is a stupid question, but will the fittings from the stock line between the master and the slave fit directly into the Howe cylinder? My clutch is being a pain in the a$$ so I am thinking of ordering Howe's cylinder tomorrow.
also, can i stick with the OEM slave cylinder? thanks.