<VV> was synthetic oil, now silicone brake fluid

[Kirby Smith]

I can provide the following anecdotal information:

I last rebuilt my brakes about 25-30 years ago and put in DoT 5 fluid, 
expecting the car to sit for a while.  It has unfortunately been on 
jackstands ever since in my garage (definitely not dry in summer, but 
lightly heated in winter, limiting temperature variation to about 50F). 
  Now that I'm back working on it, I thought it was time to bleed the 
brakes, which I did a few weeks ago.

I put a considerable amount of replacement DoT 5 fluid through the 
brakes and none of the waste fluid showed water globules.  One brake 
cylinder was found to have an incomplete bleed passage (no idea how it 
got fluid in it to begin with).  When I removed the cylinder to 
investigate why it wouldn't bleed correctly, there was no sign of water 
pooled in the brake fluid, or corrosion on the cylinder walls.

The brake system does have teflon brake lines, but there is potentially 
water transpiring rubber at the cylinder ends and in the dual master 
cylinder cover.

Putting the car on the road could lead to other results.  Since I won't 
be driving this car hard until the rings are seated once I get it on the 
road, I will keep it DoT 5 until then, at least.

kirby


Bill Elliott wrote:
> Moisture can enter the system in lots of ways. First and foremost is in the air suspended in the fluid. 
> Silicone fluids carry much more air than glycol fluids, so while the fluid doesn't actually attract moisture 
> like glycol does, it already carries more when fresh.
> 
> Moisture can also enter through microscopic pores in soft brakes hoses and seals, cracks/leaks in the 
> hoses or lines, air that is drwn into the resevoir as the pads or shoes wear, and each time you open the 
> master to check the fluid level.
> 
> It takes only a very small amount of moisture to pool and displace as steam for the pedal to go to the 
> floor.
> 
> Hey, if it works for you, great! I'm not trying to change any minds of those that have used it with no 
> problems and will likely continue to use it (regardless of what I say) until/if it fails on them.   I'm simply 
> trying to give information to those considering it and only getting one side of the story.
> 
> There is absolutely no reason to wear a seat belt either... until it's needed. Lots of folks drive around 
> their entire life without a seat belt and live to tell the story. Other, like me, see the results of a single 
> accident without a seat belt and make the decision to always wear one. Even though it's a bit more 
> trouble (just like regularly flushing brake systems are) I like the extra measure of safety it provides.
> 
> Bill Elliott
> 
> 
>>Corvair at fnader.com writes:
>>Even the high boiling points don't work in practice as the water that 
>>invaribly does get into the system pools in the wheel cylinders and boils much 
>>quicker than the water-laden glycol based fluids.
> 
> 
>>Bill & all,
>>I'd like to know how all of this water is getting into the brake systems out 
>>there.  My brake systems are closed systems sealed off from the atmosphere.  
>>If you don't let the master cylinder cover off or check the fluid level in the 
>>rain, water should not be getting in.  Even driving through water is sealed 
>>out of the wheel cylinders by the piston seals and a positive pressure that is 
>>always on them.
> 
> 
>>Ed Corson (CORSA & Amsoil cult member)
>>Inland Empire Corvair Club
>