Bleeding silicone brake fluid

There is one major disadvantage with Silicon fluid though. It's not hygroscopic.

This means that any moisture that gets in to the system, will gather, and eventually work it's way to the lowest point in the system, which is typically the brake calipers/cylinders. Where it'll then sit, until the brake caliper/cylinder reaches the boiling point of water, then boil in to steam, giving you some nice brake fade until things cool down again. However, flushing the brake fluid out won't get rid of that water sitting in the bottom of the caliper/cylinder, as the bleed nipple is at the top.

Hygroscopicity is the main advantage of conventional brake fluids. It may sound like a major weakness, but the fact it absorbs water is an advantage. Rather than the above scenario, any moisture gets absorbed into the brake fluid, where it gradually lowers the boiling point of the entire system (unless of course the brake fluid becomes saturated), and by routine maintenance (ie changing the fluid every two years), the brake fluid boiling point should never drop below critical levels. Plus 90+% of any moisture should get flushed out with a fluid change.

The same goes for LHM, and I'm not aware of any dreadful problems caused by moisture in Citroen (and other) systems using it.

Ian

Ian gurgled happily, sounding much like they were saying:

Indeed. It's a bloody big ADVANTAGE, not a disadvantage.

Modern hydraulic power brake systems will still work with air in the system, albeit with a delay in the time taken for them to apply/release while any air/vapour is compressed/expanded. This is due to the fact the pump pressure acts directly on the braking system, and doesn't rely on a fixed displacement once the pedal is pressed.

Modern?