clutch pedal squeak

I have searched all over for the answer to this. Everyone seems to give up and just buy a replacement master cylinder. At first I thought it was the pivot where the pedal is attached but lubing did not work. Then I thought it might be where it goes through the firewall and lube didn't help. Mine only squeaks if it is hot outside. Only in summer and after 10-15 minutes of driving. But once it starts it lasts all day till night then it stops. This really wouldn't bother me that much but when it starts squeaking it will not allow the clutch peddle to come all the way back up so the clutch slips if i push the gas peddle more than halfway down. I am going to take a wild guess and say it is the rubber piston seal in the master cylinder. It swells up with heat and squeaks. Once it swells up even more it hinders the travel of the piston. I will be taking mine off this weekend to check it out and confirm. Will post results.

check the cables and the clamp that hold it in place. Mine broke at 60k mi. before that had same sympton. you may be able to grease it and prevent breakage. exp dealer part , was over 200 for a cable.