Re: Treadle-Vac master cylinder losing fluid mysteriously

Posted by BH On 2021/11/28 9:41:08

If the plunger rod in the hydraulic section is pitted, it will work like a cheese grater on the big rubber seal. Then, fluid finds it's way back toward and could end up in the vacuum cylinder. There are reproduction plungers available that are now made of stainless steel.

However, how much time has elapsed between top-offs? Unlike more modern vehicles, the BTV was not sealed to atmosphere, and over time, the fluid will condense due to evaporation - even when the vehicle is not being used for prolonged periods. This ultimately leads to the congealed mess that is often found when trying to revive one of these cars from a long sleep.

In a past thread, someone provided sources for a replacement cap used with trailer brakes that has a diaphragm/bladder that will fit the BTV.