Clutch Slipping When Hot

[Tiggie]

I have a '95 2.3L/M5OD with 123K, stock clutch and transmission has never been out.

My clutch won't engage when hot (as in it slips or barely grabs at all). The problem is worst after a long highway run with the A/C on, parking for 5 minutes, and then trying to drive the truck.

It works fine when cold, and works fine as long as it's not too hot outside. The problem gets worse with A/C on - the engine gets hotter and therefore the clutch does too.

This seems to be the opposite problem of everyone else!

I flushed the fluid in the slave today. It wasn't dirty and I got no bubbles. I tried to check for residual pressure and got none, but the clutch was operating enough to drive at that point (although still not normal, only fully engaging at the very top of the pedal).

No noises or difficulty getting into gears or between 1st/reverse.

Any ideas?

 

[4x4junkie]

I had something very similar on my Ranger once (does the clutch pedal feel like it's pushed tight up against it's travel stop with no free play?)

Try this:

After the truck is warmed up and the clutch starts slipping, crack open the clutch bleeder valve on the side of the trans for a moment.
If a small burst of fluid comes out and the clutch then begins to work normally (until your next cool-off/warm-up cycle), it's because the fluid bypass valve in the master cyl is stuck closed. Fix is to replace the master cyl.