Be aware of your clutch’s action. Although a clutch/pressure plate system wears gradually over time, eventually the clutch’s performance may become noticeably diminished, and by paying close attention to how it engages, slippage should be apparent to a competent driver. Here are some simple signs to watch for:
A change in engine speed without noticeable acceleration. While driving in 3rd gear and your foot is off the clutch accelerating quickly if the car revs climb and there is no noticeable speed increase, it can mean your clutch isn’t delivering the boost in RPM through the transmission to the drive wheels.
If there is change in the clutch pedal height where the driver feels the clutch begin to engage.
Change in perceived engine power when pulling a load. A slipping clutch reduces the amount of power delivered to the drive wheels.
Push down on the clutch pedal. Your clutch may need to be replaced if it takes only a little of the pedal movement to disengage it. There should be an inch or two (2 to 4 cm) of free movement of the pedal before the clutch starts to disengage. If it disengages sooner, this is an indicator that your clutch is not riding (i.e., is not partially disengaged) when the pedal is not depressed.
If you notice a smell coming from under the bonnet. This may be the result of an oil leak or even damaged electrical wiring (both serious, but not clutch-related issues), but it can also be a sign of a slipping clutch. Most of the time if you are towing a caravan or trailer on a steep hill and you smell a pungent smell coming from the engine it could mean the clutch is slipping.
Check the clutch fluid level. Check the clutch fluid reservoir, which is located near the brake master cylinder. The reservoir should either be filled to the top, or somewhere between the minimum and maximum lines shown on the reservoir. If necessary, add fluid to the reservoir.
Some vehicles use the brake master cylinder for the clutch. If this is the case, make sure there is brake fluid in the master cylinder.