If your clutch has been feeling “spongy” or doesn’t want to fully engage or disengage, you should change your hydraulic clutch fluid. Luckily, the process is easy and should take only an hour to complete. Gather the tools listed and a friend, and then follow the directions below.
Step 1 - Locate the Bleeder Valve and Attach Tubing
First, check your owner’s manual to find the location of the bleeder valve on your clutch system. It’s often located near the bottom of the clutch slave cylinder, on or near a hydraulic line leading to the cylinder. Once you’ve located the valve, fit the clear, plastic tubing around the valve, and run it into the clean container you have. You can use whatever container you have on hand, like an old milk jug.
Step 2 - Check the Fluid Level
Next, you should check the level of fluid in the reserve reservoir. Again, check your manual for its exact location, but you can often find it near the rear of the engine compartment on the driver’s side.
Add fluid to the full level. You will likely want either DOT-3 or DOT-4 fluid, though you should use the type your manual recommends. It’s important that the reservoir never empty completely during the fluid flush or replacement process, as this will allow air into the hydraulic system, severely limiting its effectiveness.
Step 3 - Pump and Depress the Clutch
Have your friend pump the clutch pedal gently a couple of times, and then press the pedal all the way to the floor and hold it. It is imperative that the pedal stay on the floor until the next step is completed.
Step 4 - Open and Close the Bleeder Valve
Slowly turn the bleeder screw with a wrench until you see the fluid moving down the tubing you’ve attached to the bleeder valve. Your wrench should likely be 8 mm, but you should check your owner's manual for specifics.
Leave the valve open until you see the flow slow, then close it fully again. Do not over-tighten it because it will have to be loosened again. However, make sure it’s fully closed, as failing to do so can allow air into the system.
Step 5 - Release the Clutch Pedal and Add Fluid if Needed
Once you’ve re-closed the bleeder valve, have your friend release the clutch pedal. The pedal may not rise on its own, so your friend may have to pull it up with his toe or hand.
Then, check the fluid level in the reservoir, and add fluid if it has drained more than halfway. When in doubt, add more fluid.
Step 6 - Repeat Steps 2-5 Until Fluid is Clean
Finally, repeat steps 2-5 until the fluid coming through the tube is clean. Watch the color and consistency of the fluid coming out of the bleeder valve. The old fluid will have a noticeably brownish tint, and it may have debris in it. When the fluid coming out of the valve through your plastic tube becomes clear, you can stop. If the fluid is clear, but you’re still seeing small debris in it, keep flushing it until it is gone. You may have to use up to two bottles of brake fluid.
Step 7 - Close the Bleeder Screw
Next, close the bleeder screw as tight as you can without over-tightening it with the wrench. You don’t want any leaks, but you also don’t want to strip the screw or the fitting.
Step 8 - Remove the Tubing and Dispose of Brake Fluid
Remove the tubing, and dispose of the old brake fluid. Most auto-parts stores have safe disposal services for used automotive fluids, so you should contact one nearby.
Step 9 - Check Fluid Levels and Test Drive
Next, wipe down the bleeder valve area with a dry rag before checking the fluid one last time. Add fluid to fill if necessary.
Then, place a piece of cardboard underneath the bleeder valve, and test the clutch by gently pumping it a few times with the engine running. If there’s no fluid on the cardboard, you can take the car out to make sure the clutch is functioning normally.