Re: Easamatic Rebuild Sources

Posted by Ross On 2013/8/22 22:55:37

The compensator valve has no communication with the relief port. Let me try to get this across one more time in another way: The relief port is only a mediating safety feature: if the fluid seal starts to leak the fluid can find its way back to the reservoir. If the vacuum seal starts to leak, the port allows air to be drawn in from above the fluid level.

If both the fluid seal and the vacuum seal leak, then fluid will will be drawn into the vacuum side and hence into the engine. That would be the "white smoke and dropping fluid level" failure mode.

When the compensator valve "sticks", or more accurately is held open by a blob of dirt or coagulated braked fluid, all the pressure generated by depressing the pedal goes woosh back into the reservoir instead of stopping the car. This is the "pedal suddenly goes to the floor" failure mode. The relief port has nothing to do with it, and plugging the port will not change that type of failure. The compensator valve must seal tight each and every time the brakes are applied, or they will simply not apply.

SO, the failure of these units comes either through "normal" seal failure as on would see in any hydraulic system, or it comes through the compensator valve not seating. That is the particular achilles heel of the Bendix Treadlevac, and that is best mediated by careful filling and occasional changing of the brake fluid.