1969 IIA 88" brake issues............

[bugeyelen]

I'm really hoping that you folks can point me in the right direction........awhile back I lost all brake pedal pressure while driving.......managed to get the truck back home without incident and then after a couple of hours went out to find the source of the problem......I first checked the brake pedal and to my surprise it was firm and seemed to be without issue.......have driven the truck since with no loss of brake pressure.......fast forward.....yesterday while under the hood(go figure) I noticed that the master cylinders rear reservoir was almost empty... I immediately assumed the position(climbed under the Rover) and looked for a leaking wheel cylinder(played this game before) but could find nothing wet..... I then checked under the master cylinder and servo for wetness and found none.....so I checked all the lines and hoses for leaks and found none.......poured some LMA in the reservoir and could hear a gurgling noise that was possibly coming from the servo but can't swear to it......pumped up the brakes and with my foot on the brake pedal I started the truck and the pedal barely dropped(maybe a 1/4") and I could hear the idle of the truck change when I depressed the brake pedal and when I let off the brake pedal. So here I am rambling and begging for your insight and knowledge. What causes the brake pressure to disappear and then mysteriously come back? Where would you guess the brake fluid is going? Does it sound like the master cylinder or servo is going bad?
Thanks,
Len

[bamarover]

Our 1971 IIA leaked at the M/C piston after installation during our recent refurbish. (It sat for almost a year while we disassembled and reassembled). It leaked on the bulkhead footwell and ran down the pedals and onto the floorboard, destroying some paint in the process:D . I would look there real good. We ended up buying a M/C rebuild kit and had it done at a local shop. About $80 parts and labor. No leaks and good pedal. Good luck!
Greg

[bugeyelen]

I'm also leaning towards a master cylinder rebuild. I just cannot figure out where the fluid is going and why the idle changes when depressing the brake pedal. Any chance that it the fluid could be sucked into the engine through the servo vacuum port? What can be done with the servo? They aren't really rebuildable are they? Are there any other servos that will swap in place of the original?
Thanks,
Len

[I Leak Oil]

Yup, it's probably leaking into the servo. Easy enough to disconnect the servo and check to se if it's wet inside.
Jason T.

[bugeyelen]

The master cylinder must be leaking into the servo as the fluid came down the footwell and behind my floor mat. All the truck bed lining has been eaten off the floorpan!
Len