Clutch Cylinder Diagnosis

AX15 behind a 4.0 HO.

My kid reported a "shifting problem" today. When I went out to check it, I pushed in on the clutch pedal, sounded like something gave and the pedal hit the floor. There is now no pedal resistance even with pumping.

Unfortunately it has the internal slave cylinder.

There is one or two small drips inside from the master cylinder, but not alot. The fluid looks dark grey to black.

Seems logical to start with the master cylinder, but looking for some insight first.

QUESTIONS:
- Does this sound like it could be JUST the master cylinder?

- Would bad/old fluid cause a somewhat sudden failure like this?

Pulling the tranny is more than I want to tackle in the driveway, I am hoping I don't have to drag it into the shop.

Turned out to be the Master Clutch Cylinder.

I found that the plunger was sticking in the compressed position.

Picked one up from Autozone that had the same issue.

Picked one up from Napa and all is well.

No leaks around the bell housing or slave cylinder, clutch feels good and transmission shifts well, so I HOPE that I found my issue.

someone told me the other day to use nothing but the girling dot4 brake fluid and it will all last a lot longer.

Given the abuse I've seen him give a clutch, and hearing how long that mess hasn't been touched, I'll be swapping my clutch fluid out soon.

87manche said:

someone told me the other day to use nothing but the girling dot4 brake fluid and it will all last a lot longer.

Given the abuse I've seen him give a clutch, and hearing how long that mess hasn't been touched, I'll be swapping my clutch fluid out soon.

Click to expand...

That was pretty much for the older Jeeps with the British crappo cylinders. The later Jap cylinders were fine with regular old DOT3 fluid. The key is to flush/bleed them once in a while.