cherokee brakes

[89cherokee]

So the brake pedal on my '89 cherokee goes close to the floor before stopping the jeep. So I read the forums and I replace the master cylinder. I go to bleed the brakes. I notice the bleed valve has been sheered off, so I replace the caliper. New master cylinder, new caliper, new fluid. I bleed the system...and now I have no pedal pressure. I read the forums and I decide to replace the brake booster...re-bleed the system and no pedal at all. Step on brake pedal and its to the floor. Did I miss something? How important is the bench bleeding of the master cyclinder? I figured I would take care of that as I bled the system? Any suggestions will be appreciated. Thanks.

 

[Bounty__Hunter]

You've got a leak somewhere, I'd closely inspect all the lines, calipers, and wheel cylinders.

 

[mud4feet]

:agree:

Check the rears........nobody every thinks about those old drums anymore. Wheel cylinders could be shot.

 

[88Wrangles]

Bench bleeding the master cylinder is a MUST!!! You'll never get the air completely out otherwise. Plus, it's really quite easy to do.

 

[89cherokee]

Ok, I bench bled the master cylinder (tight as a tourniquet) and when I was reconnecting the lines I noticed the rear brake lines kept the pedal tight. When I reconnected the front brake line...pedal went to floor. I removed both wheels and checked the lines and calipers ( I had just replaced the passenger front caliper) and no leak. I would think with air coming in, I would see evidence of a fluid somewhere. Any suggestions on finding the leak in the front lines? Thanks for your help.

 

[88Wrangles]

Did you blead them at the wheels again after you bled the master cylinder and put it back on?

 

[88Wrangles]

I'll also add that any external leak should be pretty obvious if there is one. Check around the front caliper pistons and all the lines for any wet spots.

After that, you could have an internal leak in the booster...but it doesn't sound like that's the case here.

 

[Snitty]

You said that you had the trouble only when the front brakes were installed... If you are sure that the master and rear half are solid, I would say to take the banjo fittings off the calipers and close them off with nuts and bolts. Have someone help you bleed each side so there is no air. This eliminates the caliper from the system. If you get pressure, you know there is a problem in a caliper. If it is still soft, you know the problem is in the line or before.

 

[89cherokee]

Here's where I am today...new caliper front left and right, new brake hoses front left and right. to go with new booster and new master cylinder. Re-bleed all brakes and ...pedal goes to the floor. No obvious leaks of fluid. In fact, no reduction in fluid in master cylinder (except when I'm bleeding the system). Should I have adjusted the pedal pushrod that engages the master cylinder? What could possibly cause the pedal to go to the floor like that? Not spongy, absolutely no resistance at all. If anyone has any ideas, I would appreciate hearing them. Thanks

 

[Bounty__Hunter]

Make sure the calipers are on the correct side, that the bleeder valve is high up on the piston.

 

[89cherokee]

Talk about your "a-hah" moments...thank you bounty hunter (and everyone else who contributed to the troubleshooting). I read bounty hunter's reply and I thought...wait a minute the bleeder valve is low. Sure enough the calipers were on the wrong sides, and switching them solved the problem.

Before you write me off as another misguided weekend mechanic...Let me explain...I purchased the first caliper at NAPA. I asked for a front passenger side caliper. I put it on and it fit. Thats' when my pedal started going to the floor. Which led me to purchase the new driver's side caliper from autozone. This one also fit, but did not solve the problem. Thank God for the forum, or I would still be bleeding the lines. Thanks again

 

[90Xjay]

Well make sure to stick around and be a part of this fun bunch.
The guys here have helped me a bunch over the years..8)

 

[Laph]

I know this is prob stupid but i'm going to ask anyways, are you pumping the brakes up when you are trying to bleed the brakes, you will have to pump the brake pedal till it get hard, then have somone press on the brake and hold it down while you lossen the bleed valve the when the brake pad goes all the way to the floor, you tighten the bleed valve again, do it till no more air comes out and it's a solid stream of brake fluid coming out.
I know i'm prob going to basic but some times we over look the small things.
laterz,
Scott

 

[Laph]

LOL, i just noticed there was a second page, now i really fell stupid :redface: Glad to see you got it fix.
Laters,
Scott