MG4EVR@aol.com writes:
> I just put a new master cylinder in my 73 midget, and am not getting any
> fluid to the rear brakes. I bled them for an hour and still can't get any
> fluid to the rears.
Open lines, plugged lines, bad master cylinder, or bad bleeding process...
Hydraulic Brake and Clutch Bleeding
Hydraulic fluid in brake and clutch sustems needs to be replaced every
couple of years, as it degrades with time & use, and exposure to water
and other contaminants. Racers usually need to bleed their brakes after
each event!
Failures in hydraulic brake and clutch systems are often due to air in
the lines- often due to improper bleeding procedures. There are several
tools available to assist, but the basic proceedure is simple, and
requires nothing more than the proper sized box wrench, and a small hose.
It does require 2 people- One to operate the pedal, and one to open the
valves. The process is the same for both brakes and clutch.
Prep:
1) If you are doing a complete flush to replace old fluid, it helps to
first suck the old fluid out with a turkey baster or some such, and wipe
any sludge out of the master sylinder.
2) Fill the resivouir with fresh brake fluid, and top it off while
bleeding the system- don't let it run out, or you get to start again.
3) Check your manual for bleed order. The general rule is to start from
the wheel furthist away, but this is not the case for many modern systems.
4) While not mandetory, it is useful to have a small, clear hose to fit
over the bleeder valve, running into a bottle or jar. This is to:
A) Be able to see air bubbles as they come out with the fluid.
B) Keep the old brake fluid contained. Most brake fluids can
destroy paint, and you don't need the slipery mess all over
anyhow.
5) Jack up the car, and support it properly with jackstands if you need to
remove wheels to access the bleeder valves.
While it may work on *a few* systems, simply sticking the hose in a jar of
fluid, opening the valve, and pumping is not advised. That only serves to
move fluid in and out of one end of the system, and doesn't replace old
fluid with new, or pump air out from the middle of the lines. You need to move
the old fluid, and any air traped in it out of the system.
Bleeding Proceedure:
1) Person in the car should pump the pedal slowly 3 or 4 times, and then
continue to HOLD pressure on the pedal.
2) Open the bleeder valve, (usually takes about a 1/2 turn of the wrench)
letting out fluid (and air) into jar. The pedal will sink towards the floor.
3) Close bleeder valve.
4) Repeat setp 1 until clear, bubble free fluid comes out.
Repeat this for each wheel (or clutch) cylinder, remembering to keep the
fluid topped up periodicly.
________
/___ _ \ Roger Garnett (Roger-Garnett@cornell.edu)
/| || \ \ Agricultural Economics | The Wayward Sports Car Centre
| |___|| _ | 3 Warren Hall | http://www.wayward.team.net/
| | \ | | | Cornell University |
\| \ |__/ / Ithaca, N.Y. 14853-7801 | (607) 533-7735
\________/ (607) 255-2522 | Safety Fast!
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