idkiliketurbos

Hey all -

As the title suggests, I'm having an issue getting the brakes to bleed on my 94 Rx-7. The car had been sitting for a long time, and there is no brake pedal pressure to be found. Upon bleeding the system, we got a ton of black, nasty looking brake fluid out of the calipers and to the point where all 4 calipers have clean new fluid coming out. However, we're having a bit of trouble getting the system to build pressure. The rear brakes are moving quite a bit more fluid than the fronts and when the rear bleeders are open, the pedal gets a bit harder. The front calipers are not moving much fluid and the pedal is soft.

I pulled the master cylinder out and took it apart after reading about people having issues with the valve located within the front piston (furthest in). I cleaned out the orifice which didn't appear to be all that dirty, regreased all of the seals, and put it back together. The master was not leaking any fluid out of the back end into the booster as that was completely dry. It seems that the same issue is persisting. Another thing to mention, when pressing the brake pedal, we hear some sort of noise by the ABS pump. I don't see any signs of leaking or anything as it is completely dry as well.

Any other ideas/insight would be greatly appreciated!

FDAUTO

iTrader: (4)

you wont always be able to see an issue with the seals inside the master cylinder. a visual inspection isn't always a reliable way to determine if there is a fault. get another master if you can or order a rebuild kit. also inspect the brake lines themselves or replace them honestly. the lines will sometimes break down internally and also the cause the issue you're having. sometimes its noticeable but most times its not. the pressure difference between bleeding and operational is tremendous so you have to be mindful of how the system acts when a/the bleeder is open vs when its not. it just sounds like you should rebuild the master and replace your brake lines.

sunkat

iTrader: (2)

Did this turn out to be the MC or ABS or other? I have almost the same symptoms (hardly any brakes, pedal doesn't stiffen up). Brakes were okay when it went up on jackstands, and then a few months later the brakes are dead (and I hadn't worked on the brakes... but it's a car that sat for years so who knows what had rotted out along the way. )There were no obvious leaks so I figured the MC had gone bad. I got a new unit, bench bled and then bled the system with a power bleeder. No change, brakes barely grab. The system holds 15 psi at the bleeder, so no leaks.

At this point I figure I must not have bled the system correctly but then I notice fluid pooling at the ABS unit. Also, when pressing the brake pedal there's a distinct whooshing sound coming from the ABS, just like the OP describes - sounds like air getting in. So I'm left wondering: (1) is air getting into the system at the ABS, (2) did I get a second bad MC, (3) is it just a bad bleed (bleeders or caliper letting in air, pressure bleeder not jolting out air bubbles, ignition needs to be in run, bad bench bleed, etc), (4) other - e.g. push rod adjustment.

Leaky ABS needs replaced/removed regardless I suppose so I'm heading for a rebleed anyway.

sunkat

iTrader: (2)

The more I read the more I think I just need a good old-school bleed. Got spoiled by the power bleeder.