Brake Bleeding
 

Well I've done some major brake work. Truck is a 69 C/10
1/2 ton P/U. Previous owner put a disc brake master cylinder and proportioning valve on the truck. It has DRUMS all around. Go
figure. He also routed the rear brake line across the top of the firewall. Again...go figure. Ok...so I corrected all that. Re-routed
the rear brake line, also replaced on of the front brake lines.
Replaced the mastyer cylinder with the correct type. Then I went
looking for a "proportioning valve" for this truck. A fella in
Crossville,Tn had the right proportioning valve, so now I've
got that installed. OK...so after doing this, there is plenty of
air in the lines. (The new master cylinder was bench bled).

So what is you favorite method of bleeding the brakes?

I have in the past just attached a rubber hose to the bleed valve and put the other end in a cup with enough fluid in the cup to cover the end of the hose. However, there seems to be a lot of air in the lines. I've heard about a device that is mounted
to the master cylinder and also attaches to all 4 bleed ports
and it just pumps fluid through the lines until all the air is gone.
Well, that's probably expensive.

At any rate what method do you guys use to bleed brakes?
Keep in mind I have to do this by myself.

Jim in Mt Juliet

:bowtie:

go to any parts store and you can buy a 1 man bleeder--similar to what your doing with the hose and fluid---just a little easier to use

For about $25 dollars at Autozone you can get a vacuum pump. Comes in handy for bleeding brakes, checking for vacuum leaks, etc. It's what I used when I replaced 4 wheel cylinders, prop valve and m/c, got it right the first time!

I have used both.With the vac pump you just pump till all air is out.Just make sure the master don't run dry.The one man bleeder is a little more running back and forth,but it is $5.00.You can get other attatchments for the vac pump,so it can be used for other things.

Ok...So I've replaced a lot of the brake system. I HAVE a vacuum
gun...I think its called Mighty Vac. Anyways, I have bench bled
the new master cylinder 2 times. I go to each wheel cylinder
and bleed them also. The problem in doing this is that if you
loosen the bleed nipple up enough to put a vacuum on the
line then air gets sucked in around the base of the bleed nipple
and you think you're pulling lots of air out of the line when all
you're really doing is pulling air in around the base of the
bleed nipple. If you cinch the bleed nipple up too much then you
can't pull a vacuum on the line. (frustration!) At any rate after doing all this, I still have NO pedal pressure. Beginning to think
something is amiss, but I'm not sure what.

Maybe the best way is to simply use 2 people with one guy
opening and closing the bleed nipple and the other guy pushing
on the brake pedal.

Jim M.
Barely Braking in Mt Juliet

brake trouble
 

have one guy pump up the pedal good a have another guy open the bleeder screw while the guy at the pedal is slowly pushing down at a steady pressure. when the pedal man is down have him tell you then close the bleeder. repeat this at each wheel cylinder until you have good pedal pressure and all the air is out.

also watch your master cylinder to make sure is doesn't go dry and you have to redo everything.

Well...day 3 of the brake re-work. I found a couple
of major air leaks in the system. One around the
connection of the rear lines to the old beat up
proportioning valve that I managed to
scrounge from a local 67-72 chevy supplier.
I tightened it as much as I dared and it still won't
completely stop leaking. I guess thats
what I get for trying to use chain store parts
with old beat up parts.

So...I bit the bullet and ordered a complete
set of replacement lines from Inline Tube
and a new proportioning valve from GMC
Paul.

Sometimes cobbling parts together works fine
and sometimes not. I think this is one of the "nots".

One valuable lesson I've learned from all
this is "the theory of bleeding brake lines
doesn't quite match the practice"

Appreciate all the advice.

Jim Moser