Debris In Brake Lines
by
John Grady
If you are working on your
brake system and are not replacing the brake lines with new pieces,
the old brake lines have to be thoroughly blown out. Likely there is
dirt, rust, debris in there.
Remove each line from the wheel cylinder and blow each line a few times with 100 PSI
air and brake cleaner.
I have a suspicion that
the inside of our brake tubes may not be coated or galvanized, or
perhaps they are coated but whatever coating was in there has long
deteriorated. This may be where the rust / crud forms. Gylcol
brake fluid will bring rust again, but it may take years. Silicone
brake fluid will stop the rusting.
We recently did the brake
system on a car and replaced all the wheel cylinders with new pieces.
Imagine my disappointment when I discovered a leak from one of the
new wheel cylinders. Looking deeper, I found debris in the new wheel
cylinder which could only have come from the steel brake lines, which
were the originals I re-used. Oh, I blew out the lines, but I didn’t
do a good enough job and apparently when I bled the system, debris
moved into the nice new wheel cylinders (!!). The debris does not
come out of the line and into bleed bottle. It gets trapped in wheel
cylinders, soon to be caught under the lip, causing a leak.
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