Hard brakes: Rear Master Cylinder empty

[JasonR.]

IH all,

The brakes are very hard on the '77 Scout II. Very stiff pedal. Checked the M/C and the fluid was GONE in the rear bowl. I added more fluid and headed off to work.

After about a week and 100 miles of driving I noticed the rear bowl was empty again. No visible signs of leakage at the fittings, proportioning valve, below the M/C or along the lines leading back to the plates on the rear end.

Any ideas where to look next? Is all of this leaking into the booster?

Thanks in advance,

[RD Durham]

Pull your rear brake drums and take a look. You probably have a leak from one of the wheel cylinders. Most likely it is small enough that the fluid is mixing with the brake dust and turning to a gummy mess, so no leak is visible.

It could also be leaking into your brake booster. The rear most seal in the MC may be bad, allowing fluid to be pulled back into the power brake booster. You could pull the MC, leave the brake lines on, and see if there is any fluid between the MC and booster.