On Sat, 18 Feb 2017 13:11:04 -0500, Jack wrote:
On 2/16/2017 1:57 PM, wrote:
On Thu, 16 Feb 2017 11:17:16 -0500, Jack wrote:
On 2/14/2017 9:07 PM, wrote:
I was told that the brake fluid should be replaced on shedule to keep
the brake lines from rotting out.
First I ever heard of that.
Brake fluid is hygroscopic - it attracts moisture -and the moisture
can cause corrosion inside the lines and cyls. The water tends to end
up in the low spots. On newer vehicles where the master reservoirs are
sealed much better thasn in the past (with rubber bellows etc) it is a
LITTLE less critical (3 years rather than 2 often recommended). The
new synthetic brake fluids stand up a wee bit better too.
It appears to me, from looking at rusted brake lines that they are not
rusting from the inside out, but from the outside in.
You are correct. Most of the reust is from outside in - and most where
the like is either running through a chassis memner, running through a
clip, or is an area where mud and salt and other crap gets trapped -
holding moisture to the line.
One exception was early VW Rabbits where the brake lines ran inside
the car, under the "horsehair" noise cushion - which got soaked when
the cowl leaked up around the windshield. The fuse panels corroded
out, the brake lines rotted out, and so did the floor.
Really a LOUSY design.
This would make
sense as even if Brake fluid is hygroscopic, air would be needed to get
them to rust. Shouldn't be too much air in brake lines. Also, someone
told me they painted their brake lines with Z-bart stuff, and never had
one rust out since doing that...
I even know guys who just took a tube of synthetic grease and smeared
it over all the vulnerable parts. Not rocket science to prevent the
failure - yet the manufacturers have not gotten it figured out yet.
My guess is Stainless lines would not rust. Not sure how much pressure
is in a brake line, but shouldn't be all that much. Looking around
seems about a max of 2000psi, not much and easily accommodated with even
thin wall stainless tubing.