vr2cym

Here’s the skinny on my 93 Rx7,

Car runs but I have no brakes. The pedal goes all the way to the floor and the LF bleed screw has no fluid behind it.

The history is as follows. Car has been sitting partly disassembled for the past 6 years, last 4 outside under a cover in southern California a few blocks from the ocean (no freezing temps, but lots of moisture). A month ago, I got the engine started and since then I’ve been trying to repair my brakes.

Initially I thought I needed to bleed the lines. The rears got flushed OK with 20 PSI and the Eazi-Bleed system. But with 20 PSI going into the reservoir I got nothing from the LF. I’ve re-installed the ABS CU and it made no difference. I’ve replaced the master cylinder and still no fluid to the LF. Tracing the other way… proportioning valve has good pressure at both inlets. ABS front wheels inlet has good pressure. ABS rear and RF outlets have good pressure, but LF is no go.

According to some old postings on the Big List Archive (circa March 2000), the ABS needs to be reset. The instructions say to run a wire between “TBS” and “GND” in the diagnostic plug and read out the ABS codes from the flashes of the warning light. My 93 plug has not “TBS” terminal, and the Workshop Manual P-46 thru P-53 mentions nothing about codes and having to reset the ABS. Moreover, my warning light goes out as soon as I start the engine, which per the Workshop Manual indicates nominal ABS operation.

So, does anyone know what the problem might be? Could the ABS hydraulic unit be dead? I have not tried to bleed the 3 good wheels and the clutch to see if this will bring the pedal off the floor.

Thanks for your help,

vr2cym

I'll dispose of all the details and weeks that went into solving this problem and will cut to the chase. The problem was a bad ABS compounded by a replacment MC which was also bad.

If you have issues with your brakes, the 1st place you have got to check is the MC. The check is simple, just tightly plug the outlet ports (careful not to strip the threads or introduce any debris) and gently apply the brake pedal. If the seals on the MC are good the pedal should stop well before you hit the floor. If not, before you do anything else replace the MC.

Once you've isolated the problem the solution will be a matter of replacing the bad component. In my case I needed to swap out both the MC and the ABS. Bench priming the MC, priming the lines between the MC and ABS, bleeding the lines just after the ABS and at each wheel was bit tedious, but the effect is a pedal response and feel that I have not experienced on any other car (well worth the effort).

BTW the posting from the archives saying that you need to reset the ABS and should read the flashes of the brake warning light is a bunch of BS as far as I can tell for the 93 model year.

vr2cym

In case I can save someone from having the same problem as I did, you must keep your brake system tightly sealed from the moisture in the air. In my case the cause of all this head-ache written up in the previous posts was a cracked brake fluid reservoir cap.

So watch how tightly you screw on the cap (the collar/rim of the reservoir is stronger than the top of the cap) and if it cracks get it replaced. Otherwise over time, the brake fuild will absorb water and your brake system will rust out from the inside.

Stage7

Thanks for sharing your experience with the situation. Hopefully it will save another member some time in diagnosing a similar problem.