Clutch MC and slave Cylinder

My 85 XJ with a manual Trans has been setting up for about 9 months. I got it running again this week (starter). The clutch peddle nearly went to the floor at first, but after extensive pumping of the peddle, it firmed up like new. The next day, same thing, pumped the hell out of it (worked it) and it firmed up like new, worked like new. The MC and the slave are less than 5 years old, maybe only 4 years old.

Does it just need daily use for a while, or is it about to give up? Any way to tell which one is bad, if one is going bad?

Should I change the fluid
Thanks.

Check for leakage on the inside of the firewall for the clutch master cylinder and at the bell housing for the slave cylinder.

In 1985, and other years, AMC was putting the wrong brake fluid in the Jeeps at the factory. It wasn't compatible with the British made cylinders. Shoulda been using Castrol GT LMA.
We would replace one or both of the cylinders as needed and would see cylinder failures in the near future.
It was determined, and I've seen this, that the fluid reacted with the flexible rubber hose between the cylinders. The hose deteriorated and sent a chrystalline, abrasive white crud through the system tearing up the seals in the new cylinders. Therefore, the recommended provedure was to replace both cylinders and the hose. In later years they switched to Japanese cylinders which were compatible with DOT 3 or 4 fluid and the problem was solved. The last clutch master I got for my 86 MJ was made in Italy and presented no problem.

Both of my new ones came from AZone, about 4-5 years ago. Not a lot of miles on them yet, maybe 30-40,000. My slave is a Nissan, as the transmission is an 82 Nissan % speed. The MC is the 85 Jeep style. I am not sure if the hose/tubing is OEM Jeep, or something else, but the original engine (gas) had 187,000 miles on it before it morphed into a Nissan diesel.

I have a badly corroded fuse box, mostly bypassed now, due to prior MC leaks. I forget which MC (clutch or brakes) did the rear leak damage to the fuse box, but most of the damage was done before I bought the rig.

I guess I should check the 82 Nissan slave specs for clutch fluid. But the new ones worked flawlessly for 4-5 years, so I doubt it is materials compatability issue. I think is more of setting up, storage issue.

Clutch master leaks in to the fuse box. The brake master leaks into the booster.

cruiser54 said:

Clutch master leaks in to the fuse box. The brake master leaks into the booster.

Click to expand...

LOL, not entirely sure, but I think I even figured out how to leak the brake master into the brake booster, and then into the fuse box also, LOL!

But rest assured, I have seen and survived a newly rebuilt brake MC leak into the brand new vacuum booster. &$%^^#@!&#$%@:shiver:, and had to replace both in less than a few 1000 miles. I replaced them both with brand new parts. :sunshine:

But you make a good point, leaks into the brake booster, are likely to get sucked into the engine.

Well I bleed the entire system, emptied the MC, cleaned it, refilled it, and flushed (bleed) the entire system with about 1/2 quart DOT 3, until it was clear and clean. What came out was nasty looking. I cleaned the front of the SC (piston-actuator), and then cycled the hell of the clutch MC/SC looking for signs of a leak, especially on the SC front, where some fluid had leaked before, while setting up for 9 months unused, but found none today. The cleaned and bleed system had great peddle action (it obviously had some air in it before), like brand new, so the overnight test is see if fluid leaks out in the overnight cold, or air leaks in, and if there is any loss of peddle travel. It had decent peddle action after pumping last week, put failed completely after the 22 F freeze we recently had, so I expect a failure overnight, but we will see.

I have new parts on hand, but it acted like it just had air in it today, when I bleed it. I was bleeding it before installing a new SC, but then the old SC firmed up like new, and did not leak so I decided to wait one day (or so) and see if it just got trapped air from setting so long, or what. I don't have high hopes, but hate to fix what ain't really broke,:laugh3: LOL.

It is amazing how much water can get into a sealed system in a brake or clutch system with brake fluid over 9 months, just setting up, and how badly it can rust as a result.

The new parts I picked up locally are both cast iron, and so were the old ones.