CLANK XVI: Brake Woes(long)
******** HELP! ************
( NOTE: I am asking the net to help me diagnose a problem bleeding brakes on
my TR2. Those who lack knowledge of braking systems, or the time to read
through a lot of technical details, please hit the delete key here...)
This is getting really old. I went out to re-bleed the brakes on the Clankster
last night. I had two quarts of brand-new DOT5 brake fluid on hand, and all
the good advice of the net. I also had a master cylinder rebuild kit.
As you all may remember, the clankster had developed a brake malfunction
during its months in storage. The brakes mostly worked, but the car pulled
heavily to the right on braking, intimating that the left caliper didn't work.
I had figured that the problem was due to a sticking caliper or a swollen brake
hose. So I ordered a caliper rebuild kit along with all the other "clank
repair" items, and rebuilt both front calipers, installing new pistons. I had
also decided to replace all three rubber brake hoses. Unfortunately, the front
hoses have proved impossible to obtain locally, and I have ordered them from
TRF, temporarily re-installing the old ones.
I had been unable to get a good bleed since all this work was done, and
listened carefully to net.advice re:DOT5 fluid, and the difficulty of keeping
it bubble-free.
( NOTE: I have been routinely bleeding brake systems with DOT5 for years,
and have not experienced any special difficulty in getting'em to work.
Essentially, the rules have been: pour gently and pump slowly. And the
Ezibleed has worked fine. In fact, back when the Clankster had its original
leaky clutch slave cylinder, I used to have to bleed the clutch every couple of
months. END NOTE )
The last time I tried to bleed the brakes, I noted the following symptom:
with the EZ-Bleed connected and pressurized, I got a soft pedal that I could
pump up. Without the EZ-Bleed, NO PEDAL AT ALL. I also noted that the master
cylinder was not "returning" very well after pressing down. I had attributed
this to accumulated glop and/or corrosion in the cylinder, and purchased a
rebuild kit.
Now, here we are at 7:00 last night. I pulled the master cylinder and took
it apart. There was a moderate amount of goo within, but no corrosion. I
dunked the metal parts in my well-used carb cleaner ( definitely time for a new
can ). Then I pulled them out, rinsed and dried throroughly with a compressed
air blast. I reassembled it with all new rubber, and reinstalled it in the
car.
( NOTE: The threads on the pressure outlet port have seen better days. Can
they be helicoiled? It's not a pipe thread, the actual seal is a tapered seat
at the bottom )
Now the system was carefully bled. I poured fluid into the master cylinder
( slowly, carefully! ) and applied pressure with the ezi-bleed. I did not put
fluid in the EZ-bleed; rather, I only used it to apply positive pressure at
the top of the reservoir. Then I went to each wheel, starting with the
farthest one, and hooked a piece of clear vinyl tubing to the nipple, cracking
the nipple open a turn or so, and waiting until clear fluid exited the hose.
Between each wheel, I disconnected the ez-bleed, and retopped up the reservoir.
When the last wheel was done, I disconnected the EZ-bleed, and, with a feeling
of satisfaction for a job well done, I sat in the drivers seat and pressed on
the brake pedal.
***** NO PRESSURE WHATSOEVER *****
At this point, I called the wife out to sit in the car and pump the pedal.
"Now when I say 'down', push down slowly and gently all the way, and then hold
it there."
Here's where I noticed the second strange thing of the evening: she would
press and hold, and I would crack the nipple, and a merest ooze of fluid would
come out. Just a bit. Where's the healthy squirt I'm used to? Apparently the
master just isn't pumping. Or is all that pressure disappearing into a giant
air bubble somewhere? Doesn't seem reasonable. Or maybe the anti-return valve
from the master back to the reservoir doesn't work? ( I replaced the rubber )
Anybody got any ideas? I just can't accept this problem being due to the
bubbly nature of silly-cone fluid: in my experience, it's harder to get a good
hard bleed with it, but it's just not that hard to get the system basically
working. There actually seems to be something wrong here...
- Jerry
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