The Ford hydraulic clutch system consists of a clutch pedal, master cylinder, flexible hard line and a slave cylinder with a bleed screw located in the transmission bell housing.
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Clutch Hydraulic System Basics
- In a clutch hydraulic system, fluid pressure is used to move the slave cylinder piston, which then compresses the clutch pressure plate, separating the pressure plate, clutch disc and flywheel and temporarily stopping the connection between the engine and transmission. When air is introduced to the closed hydraulics system, it reduces the "work" the master and slave cylinders can do because air is compressible and fluids are not; the result is that the pressure plate can not break the connection between the engine and transmission, as well as difficulty with engaging gears at a stop. Often the vehicle will creep or keep moving even with the clutch pedal fully depressed.
Bleeding a Clutch Hydraulic System
- There are two ways to bleed a clutch hydraulic system. The first is to fill the master reservoir and have a helper push down on the clutch pedal while you open the bleeder screw on the slave cylinder. Have your helper keep the pedal to the floor until you close the bleeder, then have them release the pedal. It's common for the pedal to stay down and need to be lifted back up by hand. Continue bleeding this way until there are no air bubbles from the bleeder. Placing a piece of 3/16-inch clear plastic tubing over the end of the bleeder will help you identify the presence of bubbles.
The other way to bleed a clutch hydraulic system is to buy a large syringe and fill it with brake fluid, then attach the clear hose to the syringe and the bleeder screw. Open the bleeder and force fluid into the clutch slave and up to the master cylinder. Push the fluid slowly so that the tubing doesn't blow. If you start with an empty clutch master cylinder reservoir the air should be out by the time it is filled with the fluid you have pushed through the system.
Tips
- Unlike brake system, the clutch hydraulic lines can take numerous twists and turns on their way to the slave cylinder, and getting the last of the air out can be close to impossible. Pushing fluid backward through the lines can be the quickest way to get all the air out. If you cannot get a good clutch pedal feel after doing so it is very likely that you have a leaking slave cylinder or a collapsing pressure plate diaphragm spring.
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