Re: [MV] Re: Silicone Brake Fluid

Alan Bowes (
Tue, 19 Oct 1999 10:39:38 -0600

"Dean L. Kellogg, Jr" wrote:

> I have changed my jeep over to silicone and am doing it on an old Volvo
> now. It sems ok, but may take a few bleedings as it has a tendency to hold
> onto small bubbles (which is one reason why it is not recommended for
> modern vehicles with ABS).

Actually, the reason that silicone fluid is not recommended for ABS systems is
that the fluid ITSELF is slightly compressible (even without any bubbles in
it), and this compressibility dampens the relatively high-frequency pressure
modulation that takes place in most ABS systems when the ABS is activated.

Personally, I haven't had any problem with bubbles in silicone fluid, but a lot
of people have. Typically, the bubbles seem to result from some combination of
shaking the fluid can before pouring the fluid into the reservoir, pouring
fluid in too vigorously, or pumping the brakes too fast when bleeding.
Naturally the first rush of fluid down an empty line will pick up a few
bubbles, but those should purge fairly quickly. One thing that may help is to
do an initial bleeding, then let it set for a few hours to allow any bubbles in
the wheel cylinders work their way to the top of the cylinders where they can
be expelled through the bleeder orifice.

Alan Bowes

To unsubscribe from the mil-veh mailing list, send the single word
UNSUBSCRIBE in the body of a message to <>.