• Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

Bench bleeding question

B

Borgli

NAXJA Forum User
Location
Hagerman
Hi, I just ordered a new brake booster (dual diaphragm) and master cylinder for my 1992 Jeep Xj.
I know that I have to bench bleed it, but I don't understand how I am supposed to getting back into the car without loosing all the fluid and air getting back in?

Also, I am getting disc brakes instead of drums. Should I get a proportioning valve of a WJ - booster and master is off a WJ- or can I just leave it stock?
 
WJ doesn't have a prop valve. But I would change the booster and master to a 95+. I wasn't impressed with the WJ one when I tried it.

As for the bleeding I would leave the bleeding hoses on until its already in the vehicle if you can.
 
Talyn said:
As for the bleeding I would leave the bleeding hoses on until its already in the vehicle if you can.
Click to expand...

this.........

you can also dump out most or even all of the liquid from the reservior for the install. the bleeding process purges the air from inside the piston cylinder, so the res can actually be dry as long as you dont push the piston in and squirt the fluid out, which would suck air back in.
it's not a difficult or as sensitive as it may seem.
i have a couple sets of hard lines bent in hoops that hang on the side of the tool box just for doing this, but most new MCs will come with plastic fittings and tubes that work just fine.
 
I always do the bench bleeding after installing the MC. There's nothing special about locking it in a vice and bleeding it versus doing it on the vehicle. Other than it helps to have a second person if it's installed when you do the bleeding.
 
I bought a bench bleeding kit which I can't seem to find a link for on amazon at the moment for fairly cheap. It came with quality hoses and all brass fittings for every size imaginable. It also was setup that once you bleed you simple unscrew the hoses and thread in plugs to keep it from leaking all over the place during the install. Then remove the plugs one at a time and thread in your fittings. The kit really made the whole process insanely simple and was worth whatever I paid for it and seems well made and likely to hold up for all my future bench bleeding needs.

Brake fluid is nasty stuff so be sure to keep it off of any painted surface during install.
 
When I did this, I used a vacuum pump and actually bled everything at the wheels. I was prepared to do the "bench bleed" procedure, but since I wanted to clean all the crap out of the brake lines anyways I just put the pump on and kept sucking until I got clean fluid coming from each wheel. Really the only thing you need to be aware of when doing this is to keep checking the fluid level in the reservoir, there is a tendency to suck everything out way before you think it's going to.
 
Sorry to hijack, I just did this swap today. And when I started it the wire for the sensor in the prop valve shorted. Is this sensor necessory?
 
I dont know. I pulled it off when doing the swap and when I started it it fried the insulation. I also just switched my ignition and starter to switches and push button. Today i noticed a wire going into those with the same color that comes from that sensor that had fried. Idk if its the same wire. Id have to look when I get home.
 
You must log in or register to reply here.

Similar threads

T
93 dual brake booster and durango master issue
Replies
1
Views
2K
XJEEPER
XJEEPER
S
Master cylinder issue
Replies
2
Views
2K
SurplusFan98
S
G
Master Cylinder/Booster Upgrade, Larger Calipers?
Replies
5
Views
1K
Anak
Anak
M
Poor pedal feel and weak brakes.
Replies
16
Views
2K
Myziric
M
M
Pedal goes to floor when turned on
Replies
0
Views
507
Myziric
M
Back
Top