bloodyKnuc

1994 Lexus GS300

A few days ago the brake pedal got started going all the way to the floor. Came on suddenly and no work has been done lately. First I checked the fluid level, just a bit low, not down to minimum but I brought it up to max. Didn't help, and level has not dropped since. So started researching and found the suggestion to compare a slow pedal push and a fast pedal push. If pressing slow goes to the floor, but pressing fast doesn't, that apparently points to a master cylinder failure. Sure enough, that's what it does, slow goes to the floor, fast gives a hard response. So it appears to me I have a failed master cylinder.

It looks like it's a simple matter to change the master cylinder. I see three bolts, a couple metal lines, a hose or two...voilą!

1) Does anyone think any different? Could the brake booster be a problem?
2) Is there a way to test the master cylinder before replacing?
3) If I change the master cylinder, what do you recommend I use?
4) Does anyone have advice, tips, or tricks?





master cylinder





under master cylinder





master cylinder starboard

bloodyKnuc

As a simple and cheap way to investigate the brake failure a bit further, I did a quick change of the brake fluid. I used a turkey baster and sucked the fluid out of the reservoir then refilled.

This helped a little but still not working properly.

The next thing I plan on doing is a complete fluid change, not expensive but a little more involved flushing the fluid through the system.

Looks like master cylinders are about 120 bucks. They look easy to change but I want to be as sure as I can before incurring that expense.