When adding or changing the fluid in the hydraulic clutch system, use a quality brake fluid conforming to DOT 3 OR DOT 4 specifications such as Honda® Brake Fluid, or equivalent. Never reuse old brake fluid.
The fluid in the clutch master cylinder is key to a smooth transition when in the friction zone of the clutch. The fluid condition can effect the clutch engagement while driving. Low levels of fluid indicate a need for service (there may be a leak in the system or the clutch pad lining may just be worn and in need of replacement). The fluid level should be inspected during every oil change, however, more often is desirable. Every time the hood is raised is a good time to glance at the clutch master cylinder reservoir.
The fluid in the clutch master cylinder reservoir is more likely to become contaminated more quickly than the brake fluid in the brake master cylinder reservoir. When the clutch pedal is pressed, it is pressed completely to the floor during every gear change. Because of this, the seals in the clutch master and slave cylinders travel much further and more often than the brake master cylinder and wheel cylinder or caliper seals, which only travel far enough to achieve proper braking pressure.
See Figure 1
To check the clutch master cylinder level:
- Wipe the clutch master cylinder reservoir cap and the surrounding area clean with a shop towel.
- Inspect the fluid in the reservoir, making sure the fluid level is between the MAX and MIN marks.
- If required, remove the clutch master cylinder reservoir lid, then add fresh fluid to bring the level up to the MAX mark on the reservoir.
When making additions of fluid, use only fresh, uncontaminated brake fluid which meets DOT 3 or DOT 4 standards. Do not allow the brake fluid container or the master cylinder to remain open any longer than necessary; as brake fluid absorbs moisture from the air, reducing the fluid's effectiveness and causing corrosion in the lines.
- Reinstall the lid onto the clutch master cylinder.