91 Jetta brake woes

[FoXBoXRaCiNG]

So...

Big km's at 483, but, new rear shoes, drums, wheel cylinders (twice), master cylinder (twice), front pads and rotors. 0 fluid loss at rear wheel cylinders, prop valve, master cylinder, or the front calipers and lines, and there are no puddles under the car else where with all the other lines underneath inspected...

Anyone with insight as to why the brake pedal does not stay firm after bleeding? Might get a few good pumps for braking, then it's just the front pass locking up 

Thanks All!

[smutts]

If the fluid is vanishing, then it's leaking into the brake servo via shagged master cylinder seals. Once that fills up, the vacuum pump will be pumping brake fluid into your engine oil, if you haven't already got roadkilled. If this is the case, don't forget that there will be several pints of excellent paint remover lurking in there jealous of your nice shiny paint or personal flesh when it gets unbolted.  

But it might just be the quirks of bleeding the brakes on Mk2's with the load valve on the rear axle. I've never really got the hang of it.

Be careful when bleeding the brakes of old cars as the master cylinder seals often get damaged as the piston travels over rough dirty or corroded cylinder walls  when pumped to the floor. Ezibleed kits help here.

[Doug]

Did you follow correct procedure to bench bleed the master cylinder according to the manufacturer's instructions? If you don't, it works like how you are describing your situation.

[Dakotakid]

I would take a very detailed look at the rear brake actuator...driver's side rear.
That leak is hard to see and I have had them go bad and render these results.
The actuator is annoying to work on, especially if you have a rust car.