hydrolic clutch from hell.... maybe overheated?

[SportinWood]

Ok here goes.... my clutch gradually goes to the floor only on the highway.......
I replaced the slave and lower line once when it blew there, ran it for a week, long drive into town, then raced around town for like 3 hours...... get on the highway and 3 hours later it slowly fades again..... replace the lower line(fluid blew out again....) Blew again on the way back home(8 hour trip) left it at mitsubishi and said fix it. They replaced the slave again, all of the hardlines, the little cylinder thingy, and the master cylinder. 2 weeks later, today, I get it back and drive it home (fife-spokane) feels fine, goes out over the pass. Get to auction to park it.... open hood, pop cap, no fluid gone. go to clutch and its halfway out after getting stuck on the ground. pump it once and its fine, perfect pressure ect..... confused... drove home (30 miles) and the whole time it was perfectly fine.... i have an aftermarket DP that does not have a heat shield on it.... the slave is near... could it possibly be that on long trips my car heats up a little more and at constant rpms produces constant heat. Could the fluid get too heated and thin/thicken??? I have no clue, their mechanic of quite some time cant figure it out. Anyone else have this problem??
Please I'm going mad!!

 

[Defiant]

Sounds like a bum master cylinder. Look for a wet spot on your carpeting.
Throw away that accumulator and hard tubing, replace it with a stainless line from RRE.

 

[SportinWood]

I drove it around all day today and it was fine, it only seems to do it on long drives... the master cylinder is bran spankin new, everything is new and hasnt lost a drop..... are you sure it isnt from the heat of the DP? Again I have no idea and neither does korum mitsubishi.....

 

[SportinWood]

This is really starting to bug me now. There was a guy in town who said it could be crankwalk. But it only happens on the highway. I drove/raced it around town for 3 hours straight last night and there were no problems at all.... maybe there was some air in the lines and i worked it out somehow??? AAUUGGHH!

 

[Defiant]

It's not from the heat. Has the clutch pedal been adjusted?

 

[SportinWood]

um I don't know, I didn't think you had to adjust hydrolic clutches. Its perfectly fine right now which makes no sense, it's only when I'm on the highway for a while that it does that........