2004 honda civic clutch master cylinder replacement

What is a clutch master cylinder?

The hydraulic clutch uses a clutch master cylinder to compress fluid inside the system, causing the slave cylinder to operate the clutch.

How does the clutch master cylinder work?

The clutch pedal is a lever that increases the amount of force you apply. When the clutch is pressed, the clutch master cylinder pushes fluid through the line, and into the slave cylinder on the other end. The slave cylinder pushes on the clutch fork, which disengages the clutch. When the clutch pedal is released, the clutch pushes the slave cylinder closed, forcing fluid back into the master cylinder, which lifts the clutch pedal and provides the force felt when pressing the clutch.

What are the symptoms related to a bad clutch master cylinder?

If the clutch master cylinder fails, the clutch pedal may float to the floor when held, and the vehicle may attempt forward motion with the vehicle stopped and in gear. The clutch will attempt to engage as the fluid escapes compression in the master cylinder. In most cases, the clutch pedal will have little to no effect on the clutch.

Can I drive with a clutch master cylinder problem?

Driving a vehicle without a working clutch is only possible if the transmission is shifted improperly, and push-started at every stop. While this may save a few dollars on wrecker services, it can cost the replacement of the manual transmission. It is better to have the vehicle towed, than risk further damage.

How often do clutch master cylinders need to be replaced?

The clutch hydraulic system, including the clutch master cylinder, clutch slave cylinder, and fluid lines, will need replacement sometime during the serviceable life of most equipped vehicle's. They wear out with use, but this typically takes well over 100,000 miles of use. For vehicle's used in city driving, the system will require much more maintenance over the life of the vehicle. Changing the clutch fluid according to the manufacturer specified intervals may help prevent premature failure of these components.

93 Civic DX here. I had a failed clutch master cylinder a few weeks ago. I am looking at a 2002 parts diagram of your system and the free online repair guide for your 2002 Civic at autozone.com . It has decent illustrations; it looks very similar to my Civic's. Hints on replacement:

I turkey basted out the CMC reservoir and then drained the system via the slave cylinder bleed valve. Then I removed the reservoir and its bracket for optimal access to the master cylinder connections. Gotta use a 12 mm brake line wrench, of course. If you do not have one, it's a few bucks at your local aftermarket auto parts store.

Did you inspect the driver's side clutch pedal for leakage where the rod penetrates the firewall? This was my tipoff that my CMC was failing.

Conventional wisdom is to replace both the master and slave cylinders at the same time. If one's seals are gone, then the other's will not be far behind. Got mine at NAPA for around $70 total. After three weeks, all works great.

Bleeding a Honda clutch system is trickier than with the brake system. Here is what finally worked well for me:

I bench bled as best I could both the CMC and CSC. Nothing fancy; just used tubes, a bottle of brake fluid, and pumped the pistons of each a few times.

Get about nine inches of 7/32-inch OD, 5/32-inch ID tygon tubing that fits over the slave cylinder bleed valve nipple really well. (My tubing came with a brake master cylinder I purchased a year ago from Napa.) Your 2002 bleed valve is exactly the same as my 1993's. Attach the tubing to the new slave cylinder's bleeder. Having a tight fit of tubing-to-bleeder is the best insurance that you will get a good bleed and hence firm clutch pedal.

Immerse the other end of the tubing in a fresh bottle having maybe 1/4-inch of brake fluid in it. I used an old but clean 8-oz water bottle and sat it on the undercarriage's protective cover. Fill the clutch MC reservoir about 3/4's full. Crack the bleeder screw. Let gravity help push air out of the system. Close the bleeder screw. Top off the reservoir again. Now repeat the following steps until you see no air come out of the bleeder screw tubing and hear no burping (air bubbles being released) from the bottle sitting on the undercarriage cover:

1. Pump the pedal 2-3x slowly (I pumped it ten times). Hold pedal down with a 2x4 piece of wood propped against a square plastic bucket in the driver's seat, lodging the 2x4 underneath the steering wheel.
2. Open the bleeder screw a tiny bit then close it. You do not keep it open more than say a few seconds, whence the air bubbles no longer go towards the bottle receiving the brake fluid.
3. Check the reservoir level and add fluid as needed. It will not need much. Do not let the reservoir go dry.
4. Lift the clutch pedal from floor back into position.

To get a firm pedal will take about 30 repetitions of the above. This will take maybe an hour. Driving around and using the clutch a bit, then bleeding a few times, may help it firm up. I think the higher temperature of the fluid after driving a bit helps air come out of solution.

I had tried my Mity-Vac pump on the system but, unlike the brakes, the Mity-Vac was a stupendous failure in getting any kind of bleed.

How do I know if my clutch master cylinder needs to be replaced?

How long does it take to replace a master cylinder clutch?

What happens when a clutch master cylinder fails?