Honda Civic/CRX/del Sol 1984-1995 Repair Guide

Brake Master Cylinder



DOT 3 and DOT 4 brake fluid is "hygroscopic." It is so prone to water contamination and absorbs humidity right out of the air. This is why it is always recommended to use fresh fluid. If there is any doubt about the fluid you are using, buy new fluid.

Use only fresh DOT 3 or DOT 4 specification brake fluid from a sealed container. If you are unsure of the condition of the fluid (whether or not it has been tightly sealed or how long it has been in storage), use new fluid rather than taking a chance of introducing moisture into the system. It is critically important that the fluid meet the specification so the heat generated by modern disc brakes will not cause it to boil and reduce braking performance. Fluid must be moisture free for the same reason.

Brake fluid is a very effective paint remover. If any spills on a painted surface, wash it off immediately.


See Figures 1, 2 and 3

Brake master cylinder fluid level should be checked every few weeks for indication of leaks or low fluid level due to normal wear of the brake lining.

On all Hondas, there is a fill line (or MIN/MAX lines) on the brake fluid reservoir(s) as well as an arrow on the reservoir cap(s) which should face forward when installed. When adding brake fluid, the following precautions should be observed:

Use only recommended brake fluid: DOT 3 or DOT 4; SAE J 1703b HD type.
Never reuse brake fluid and never use fluid that is dirty, cloudy or has air bubbles.
Store brake fluid in a clean dry place in the original container. Cap tightly and do not puncture a breather hole in the container.
Carefully remove any dirt from around the master cylinder reservoir cap before opening.
Take special care not to spill the fluid. The painted surface of the vehicle will be damaged by brake fluid.

Click image to see an enlarged view

Fig. Fig. 1: Brake fluid level in the master cylinder reservoir should be monitored regularly

Click image to see an enlarged view

Fig. Fig. 2: Clean the master cylinder reservoir cap before removing it

Click image to see an enlarged view

Fig. Fig. 3: Always add new brake fluid-be sure to wipe up any that might be spilled