How to Replace the Master Cylinder on a 1980 Volvo 240

The brake master cylinder supplies high-pressure fluid to the brakes when the pedal is depressed. The master cylinder on a 1980 Volvo 240 has a translucent fluid reservoir on top of the master cylinder, making it easy to check the fluid level. The level should be checked often so an impending problem can be cut off at the pass. Brake leaks, especially on an older vehicle, are common. Loss of brakes can have serious consequences. There is a line inscribed in the reservoir for quick reference. As a note, brake fluid destroys paint quickly if not washed off immediately.

Tools Used: Ratchet, Set of sockets, Set of line wrenches, Phillips head screwdriver, Vise (Optional), DOT4 brake fluid, Clean cloth

Replace Master Cylinder

Place a cloth under the master cylinder to catch any fluid that may be lost when removing the brake lines. Break the two brake line fittings loose with a line wrench but do not remove them. Remove the two nuts securing the master cylinder to the power brake booster or firewall if the vehicle has no power brakes.

Remove the brake line fittings that you broke loose in the first step. Pull the master cylinder off the mounting studs, remove the reservoir cap and empty the remaining brake fluid into a container for disposal. Remove the translucent reservoir, which is simply snapped into the rubber grommets on the master cylinder, pulling it off.

Install the original reservoir on the new master cylinder. Clamp the new master cylinder in a vise if one is available. If not, lay it on a hard surface. Install the two plastic fittings in the master cylinder. Install the two hoses, supplied with the master cylinder for use in bleeding it, onto the fittings. Hold the two plastic hoses in the reservoir while you fill the reservoir with brake fluid.

Hold the master cylinder so it can't move and use a Phillips head screwdriver to pump the master cylinder in and out to evacuate all the air. When no more air bubbles are present in the reservoir, stop.

Hold the hoses in the reservoir while you install the master cylinder on the mounting studs. Install the nuts and tighten with the socket. Remove one plastic fitting at a time and thread in the metal brake line then tighten.

Fill the master cylinder reservoir to the "Full" line with DOT4 brake fluid and replace the cap. Wash off any brake fluid that may have landed on the vehicle's finish.