I don't want to get too in the middle of this, but my take on it is:
1) Absolute safety, use fresh fluid
2) Enrique's comments make sense, but you'd have to definitely know what
you're doing and be willing to bet your life on it.
3) The dire warnings on brake fluid I think were initiated because of
mechanics who would drain off brake fluid, stick it in a (dirty or rusty)
can somewhere, and haul it out later and reuse it at a later point in time,
often with deadly results, either to themselves or to their poor customer.
Thus the warnings "never to reuse".
4) As far as draining it out of the system to recirc it, you'd have to make
darn sure it was clean all the way through. Personally I wouldn't be
inclined to have any opportunity to introduce any contaminants, but if
those who try really know what they're doing and are assessing the risk and
betting their lives on it, I guess that's up to them. In other words, I
wouldn't want my mechanic doing it to me, but if he did it to himself
that's his perogative, as long. It is an enclosed circulatory system, so
if you can intercept it cleanly, it's hard to say or argue that it wouldn't
be safe, though I'll take the weenie route and use fresh stuff.
- Tab
At 09:43 PM 11/5/99 -0400, Enrique Claure wrote:
>Hi folks, here is my last take on clutch bleeding and fluid reuse. First of
>all, there is no reason why "clean" brake fluid can not be recirculated in
>a "clean" system. The fluid does not decompose or interact chemically with
>any other substance and thus remains chemically stable for quite some time.
>The fluid eventually absorbs water and thus losses some of its hydraulic
>properties and is no longer inert to system materials. As far as the fluid
>goes, it does not remain static inside the system. By design hydraulic
>systems are dynamic and every time you press the pedal the fluid moves
>inside the system, interacts with the system walls and moves around itself.
> Recirculating fluid is thus safe as far as the chemistry of the fluid.
>Lets talk particles, there are three important particles that contaminate
>the system. Oxides from the system, dirt (in the form of dust, soil, etc)
>and micro bubbles. How can you remove these? filtration. I would recommend
>to put a filter on the end of the pipe that goes back into the system from
>the nipple. Since I have access to laboratory materials I have managed to
>use a VW gas tank mesh filter made of polyethylene with Whatman filter
>paper No.1. This step will trap most all dirt of significant size that can
>cause brake problems and also coalesce micro bubbles. I believe that
>flushing the system before doing a serious bleed is of utmost importance.
>Recirculation done safely and properly with a good final filter is possible
>and can be a safe and fast way to bleed your brakes and clutch. Enrique
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