UK Car Repair: engine revs doesnt decrease when clutch depressed, worn clutch, clutch pressure plate

Question
Hi. I think this will be a simple 1 for you.
When i depress the clutch the engine continues to maintain revs. This happened for the first time yesterday and hasnt happened since.Is it likely to get worse and would it eventually cause the car to breakdown if i didnt fix it?
It is an old fiesta diesel.
Thanks

Answer
Two things can cause this problem, a clutch that is in some part failing, or a governor that is sticking. Diesel engines are more for low RPM torque than high rev HP like a gas engine. The governor meters fuel and prevents over revving the engine. If the spool valve is sticking it can cause a momentary hang when shifting or clutching. A worn clutch pressure plate or throw out bearing can also cause this by not fully disengaging the flywheel on the engine and allowing it to up rev when you shift. I would be more inclined to look into the governor and metering/injection pump to solve this, however, a little fuel treatment might make this problem go away and solve your sticky pump problems.

Regards,

John