I have a 91 YJ Wrangler. I had a friend replace the slave cylinder a couple months ago because and that was a real pain. We are losing fluid again so I think we need to replace the master this time. I heard they should have been done at the same time. I hate to take it back to my friend so I'm hoping its fairly easy for my son and I to do. Any help is greatly appreciated. Also any other ideas if you don't think the master is the problem. Thanks.

1995 YJ if still stock all that is ONE PART, see FSM quote below.
is the fluid dropping, day by day, week by week???
y/n?
yes, then either the slave or mc are bad.
sometimes both can fail, (rust happens inside and is progressive)
what I do , is this. (if not wanting to change out both)
1: look at the MC, if it done leak down either side of the fire wall
it might be good (dont mean the piston seals good but its not leaking, so if fluid drops , (every week say) the the MC is ok
and for sure the slave leaks.

2: so where is your slave. have you looked,? (swaps happen)
most leak and can not be detected as that leak landed on the road to work.
for sure its just 2 parts, here, you know the clutch is ok.
because it works with fluid in the system and bled.
now ILL PASTE THE FSM words out of a real factory service manual.
they are clear.
FSM words, QUOTE:
CLUTCH HYDRAULIC LINKAGE REMOVAL
The clutch master cylinder, slave cylinder
and connecting line are serviced as an assembly
only. The linkage components cannot be
overhauled or serviced separately. The cylinders
and connecting line are sealed units. Also
note that removal/installation procedures for
right and left hand drive models are basically
the same. Only master cylinder location is different.
(1) Raise vehicle.
(2) Remove fasteners attaching slave cylinder to
clutch housing.
(3) Remove slave cylinder from clutch housing (Fig.
9).
(4) Disengage clutch fluid line from body clips.
(5) Lower vehicle.
(6) Verify that cap on clutch master cylinder reservoir
is tight. This is necessary to avoid undue spillage
during removal.
(7) Remove clutch master cylinder attaching nuts.
Note that one nut is accessible from engine compartment
and one nut is accessible from under instrument
panel (Figs. 10 and 11).
(8) Remove clip securing clutch master cylinder
push rod to pedal and slide push rod off pedal pin.
(9) Disconnect clutch pedal position switch wires.
(10) If pedal pin is equipped with bushing, inspect
condition of bushing and replace it if worn or damaged.
(11) Remove clutch hydraulic linkage through engine
compartment.

this is a faulty clutch master cylinder

The clutch hydraulic control unit cylinder seals have failed. It is inside the bell housing and will need to be replaced.

http://t3.gstatic.com/images?q=tbn:-uQXZrnPohb3WM:http://shop.oreillyauto.com/product_images/img/ben/12305_040106.jpg

If you go to this page... then allow pop ups and enlarge the image it is upper right in the picture here:

Here is a parts source.... the cylinder is 3/4 of the way down the page scrolling.

http://www.jeep4x4center.com/jeep-clutch-parts/wrangler-yj/index.htm#cylinders

What ever you do... verify that the part is actually leaking. It could be a leaking line and these are NOT cheap to replace. Jeep finally figured out in 1994 they should once again be using a slaved cylinder.

Thanks for using FixYa.

Kelly

It is likely leaking at the slave cylinder

Check the clutch master cylinder, the line to the slave cylinder on the bellhousing and the slave for leaks. If fluid is low there is a leak. Master can "bypass" as well similar to a brake master in which case it wont leak but the slave won't move when the clutch is applied. If that system is working then the clutch likely has worn out.

Pushing the clutch pedal it to disengage the clutch, so your description is confusing. But if a car creeps when the clutch is down, you must immediately adjust the clutch, or you will ruin the transmission. However I believe you have a hydraulic clutch linkage, so the slave or master cylinder could also be bad. Peel back the rubber boots to check for leakage.

Did u bleed the system to get rid of the air. Put fluid in the resovoir, open the bleed valve on the slave cylinder, put a hose on the bleeder valve and into a container with clean fluid and pump the clutch until no bubbles-close the valve and remove hose, check resovoir and top up--system is now bled.

no, there is no clutch adjustment. the clutch is hydraulic, and self adjusting, there are several things that can go wrong with these. with normal wear the fluid can run low allowing air into the system, causing a weak peddle. they can also develop leaks in the master and slave cylinders resulting in fluid loss also causing a weak peddle leading to an inopperative clutch. check the fluid level in the clucth master cylinder(next to the brake master cylinder. if it is empty, refill it(it takes brake fluid) then cycle the clutch peddle a few times and check for leaks. if there is air trapped in the line the clutch will need to be bled. there is a bleeder screw on top of the slave cylinder, bleed it just like bleeding brakes.

check for leak at the push rod for the clutch master under the dash and also the slave cylinder and replact the leaking part

slave cylinder needs replaced