Listed below is a listing of all the suggestions I got so they will be
available in the archives. I am very amazed at the number of off list
replies I got. After my comment about copying the list, a few responded
their reasons. Primarily due to "lack of etiquette, respect for others call
it what you will" from commenters on the list.
Well I am posting all of the suggestions (which are all very good and good
be applicable for someone).
My problem was the split reservoir. Need to make sure you keep the back
higher than the front. My carport has a very small slope. Not even enough
to roll a socket. Also watch the fluid in the front very carefully.
I had a similar type problem. I thought that I was filling up the reservoir
on the master cylinder. What was happening was that I had the car up on
jacks working on the brake system. The front of the car was a little higher
than the rear. This was just enough to give the impression that the
reservoir was full, when in fact the front part of the reservoir had no
fluid
in it at all. The front of the reservoir is what powers the rear brakes.
There is a separator between the to half's of the reservoir. It runs to
like 80-85% of the reservoir and the tilt was not letting any fluid get to
the front.
As soon as I put the thing back level, I started seeing fluid coming from
the rear wheel cylinders and they bled just fine.
This may not be your problem, but I pulled my hair out until I found this
tip on www.mgbexperience.com. I checked it out and indeed that was the
problem.
Check the metal lines going from the connector on the diff to the wheel
cyls. I
have customers' cars towed often and if the tow co. uses a flat-bed and
hooks
they crush the metal lined on the diff tubes and thus NO BRAKES.
Wow! I am at a loss to explain your problem, but let's go one step at a
time. It sounds like you have already done everything to check what I would
check, but over a year's time, something could get lost.
Chances are the rear wheel cylinders are the problem, but you said you
replaced them with new. Otherwise, I would suspect the new master cyl.
Step 1 - Did you properly adjust the rear shoes before bleeding? If the
shoes aren't near the drums, no amount of bleeding will make the rear brakes
work.
Step 2 - If yes, remove the bleed screw entirely from the wheel cylinder.
Press the pedal. If you get brake fluid out of the wheel cylinder, the
bleed
screw is clogged. Replace it. If no brake fluid proceed below.
Step 3 - Remove the brake line from the wheel cylinder and press the pedal.
If you get brake fluid, the problem is the new wheel cylinder. If no brake
fluid proceed below.
Step 4 - Follow the brake line back to the next junction. (I have a Midget,
so in my car it would be the T joint after the flex line. Dunno about a B,
but find the next line connector.) Disconnect it and press the pedal. If
fluid comes out, the problem is THAT line or T connector. If no brake fluid
proceed below.
Step 5 - Continue moving back the brake line (toward the master cyl.) and
disconnecting each joint, until you get brake fluid flowing freely when you
press the pedal.
If everything in Step 1 & 2 was OK, then I would say the master cylinder is
bad. New master cylinders can be bad. Remove it, wrap a rag around it and
put it in a vise. Bench bleed it and see if fluid comes out both holes. To
be absolutely sure it is good, send it to White Post Restorations for
re-sleeving. It is expensive, but you can be sure it will be right.
Did you bench bleed the Master? If not, you will have to bleed it on the
car. Two ways- crack the fitting where a brake line joins the master, and
bleed the master by leaving the fitting loose, press pedal, tighten fitting,
release pedal, repeat until no air. Then do it for the other brake line.
Alternative-disconnect brake line and using a syringe, inject brake fluid
into port until no air. repeat with other line.
Also, by this time, you probably have air in the lines. Starting at the
master, bleed the system at every fitting working toward the rear wheels.
Check the line along the rear axle, it sometimes gets pinched by a tow hook.
Also check to make sure that the fittings are all tight, especially where
you replace components.
So if the lines aren't plugged, and fluid will go through them attach
the lines back to the master cylinder, leave them disconnected from the
wheel cylinders and see if depressing the brake pedal will push fluid
out the lines. If not I would suspect the new master cylinder.
Let's be sure that the MC, even though new, is working. Disconnect
output line to rear brakes at the MC and install a short chunk of the old
pipe as a test pipe. Press the pedal and see if fluid is coming out. You
might put some heavy plastic bags around the end of the pipe and try to
block with finger pressure to see if there is hydraulic pressure there.
Last time I rebuilt a '72 MGB MC, the little link that joins primary
and secondary cups broke after the MC was reinstalled, so secondary cup
went to back of the cylinder and stayed. That's why I could not get rear
brakes to pump. grrrr. Bought another rebuild kit and scavenged a link,
and now it does work as it should.
Stupid question time, is the bleeder on top?
Another option, your bleed technique wasn't too specific
but isn't quite the standard, at least the one I use.
I open the bleeder, then push to the floor, then close
bleeder.
Some people push the pedal to the floor, then open
the bleeder and close it. I've never done this and it
probably works.
Phil Farmer
870-367-3318 home
870-818-6623 cell
253-550-3609 fax
pilot@ccc-cable.net
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