Clutch won’t shift on a HOT day. When its hot I can’t shift very easy between gears. However, the clutch is newer and so it works just fine. When its cold its sometimes tough but not as hard at all. Could it be a clutch master cylinder or slave cylinder? Do I need to bleed it?
More than likely the problem is with the clutch master cylinder leaking internally.
When it gets hot out the underhood temperatures increase. These higher temperatures heat up the clutch master cylinder located under the hood on the firewall. This increase in temperature causes the bore within the master cylinder to increase in size. And if the seals within the master cylinder are worn, this then allows the hydraulic fluid to bypass the seals within the master cylinder to where it isn’t able to produce the hydraulic pressure to operate the slave cylinder to release the clutch. So it would be like trying to shift into gear without stepping on the clutch pedal.
To confirm if this is what’s happening, the next time it’s difficult to shift, open the hood and pour cold water over the clutch master cylinder and then try shifting into gear. If shifting is easier the clutch master cylinder is being effected by heat and should be replaced.