still have no brakes in the xj

[McJesse]

I've replaced master cylinder brake booster new brake cylinders shoes srem fine can't see any holes in the line. What it does is it seems to buildup some pressure when its off and then when its running I have no peddle at all any ideas?

 

[McJesse]

It's an 88 laredo

 

[Lowrange2]

You still have air in the lines.

You need to bleed it more.

What bleeding method are you using?

 

[OutkastBoss]

x2 on air in the lines I've been there (someone taught me how to bleed brakes wrong the first time)

 

[McJesse]

One person pumps the peddle and they hold then yoy work your way farthest away from master cylinder

 

[Fidget360]

the build up in pressure in the pedal when the engine is off is the vacuum in the booster disipating. I'm with these guys. if there's no leak anywhere there's gotta be air in the lines.

 

[Lowrange2]

Right, but it's a bit more detailed than that...

I use a bottle half filled with fluid. I take push a hose on the bleeder and stick the hose in the bottle.

I then have the helper pump the pedal a few times then hold the pedal 1" off the floor. No more, no less.

Crack the bleeder open and watch all the bubble come out of the end of the hose.

This prevents it from sucking air back up when you open the bleeder.

Do each bleeder this way 4 or 5 times and I promise you'll get the air out. It takes time.

Why didn't you upgrade the MC and Booster to a late model while you were doing it?

 

[McJesse]

Alright ill try that thanks

 

[McJesse]

I'll let you know if it works

 

[Flyfisher]

Oh, and be sure to do the wheel farthest from the master cylinder first (right rear), then work closer to master cylinder. Not sure that was clear from your post about how you were doing the bleed.

 

[1990JEEPXJ]

did you bench bleed the master cylinder?

 

[Lowrange2]

did you bench bleed the master cylinder?

AH! Forgot about that. He did say he changed the MC.

If not, pull one of the brake lines off of the MC. Put your thumb over the hole in the MC, have someone pump the brakes. It should only take 1 pump. When the fluid starts to push your finger off have them let go of the pedal (Try not to let much more fluid run out) and put the line back on.

Now that he mentions it I bet that's your problem.

 

[Dirt Yota]

Right, but it's a bit more detailed than that...

I use a bottle half filled with fluid. I take push a hose on the bleeder and stick the hose in the bottle.

I then have the helper pump the pedal a few times then hold the pedal 1" off the floor. No more, no less.

Crack the bleeder open and watch all the bubble come out of the end of the hose.

This prevents it from sucking air back up when you open the bleeder.

Do each bleeder this way 4 or 5 times and I promise you'll get the air out. It takes time.

Why didn't you upgrade the MC and Booster to a late model while you were doing it?

This is a good method. You can also fill the bottle, crack the line and let them pump away. It will push the air out and not allow the air back in since the hose is 'under water' (aka: Brake fluid) and it acts as a one way valve.

 

[McJesse]

did you bench bleed the master cylinder?

Yeah I bench bled the mc

 

[McJesse]

This is a good method. You can also fill the bottle, crack the line and let them pump away. It will push the air out and not allow the air back in since the hose is 'under water' (aka: Brake fluid) and it acts as a one way valve.

Yeah thats what i was thinkin bout doing but thanks for giving me the tip

 

[stockli]

Dont forget to bleed the prop valve as well.

I had this problem on an 89.

Also make sure you dont mash the brake pedal to the floor or you will booger up the piston in there and wreck your new master.

 

[Fidget360]

where did you get the new master cylinder from? There is the chance that it's bad right out of the box.

 

[McJesse]

where did you get the new master cylinder from? There is the chance that it's bad right out of the box.

I got it from schucks or "o'reily" now

 

[McJesse]

Dont forget to bleed the prop valve as well.

I had this problem on an 89.

Also make sure you dont mash the brake pedal to the floor or you will booger up the piston in there and wreck your new master.

K thanks for the tip I mean it could just be another bad master cylinder

 

[Lowrange2]

Did you try bleeding it more?