1990 Cherokee Brake Issue.
 

Bought a 1990 Cherokee for a hunting rig from my buddy a couple weeks ago, Lardeo V6 4x4. Brakes need bleeding per him. I have bled them multiple times with truck off and they feel like there stiffening up until you crank it and they go all the way to the floor and have very poor braking. He states the right front brake locked up on him, so he got a replacement caliper from you pull it and could not get the brake to bleed. I went a head and bought a new master cylinder and bled them by myself with and tried a bleeding tool which didn't seem to help. I had someone help me and pump the brakes (slowly) until the fluid was clear. I start the further est caliper away and worked my way to the closest. I did read bench bleeding the new master to aggressively (compressing master to deep) can damage it. I went a head and ordered a new master cylinder just in case I damaged it and two new front calipers. I will check all the lines and make the lines are not cross threaded or stripped. I assume the brake booster is okay since its not hard when engaging brakes. Just wanted to get some advice or tips before I jump back into it this Friday. Are these jeeps difficult to bleed the brakes? Or am I missing something? Any help would be great.

The calipers will interchange. Make sure the bleeders are on top.

Yes, the bleeders are up top. I did verify that to make sure.

Your not starting from the farthest brake in the back?

Yes, starting RR, LR, RF, LF.

I assume the combination valve doesn't need anything special, I hear that's a issues when the rear brakes lock up.

Never had a problem bleeding because of the proportioning valve. Since your bleeding in the right sequence have you bleed the master cylinder last?

No Did it first on the bench and then hook everything up and bled from calipers

Follow your sequence from back to front then bleed the m/c last. Work the brake peddle and bleed it the same way as the others. Just open and close the fittings until there is no air. Doesn't matter which fitting you do first.

If it has ABS the problem might be a failure of the system, it's very troublesome and dangerous and should be deleted.

If it's non-ABS then I don't know what could be causing your issues, there's nothing particularly odd about the system and should be easy to bleed.

Non ABS system, I was thinking the system should be easy to bleed also. Done it before on multiple cars with no issues. I'm going to replace front calipers and removed the remanned master cylinder and return it for a new one. I will check the lines and bolts to make sure nothing is loose or cross threaded. Any tricks on checking the lines, using soapy water for leaks, etc? But this is my tentative plan thus far.

I just did a m/c replacement on an '84 F-150 last week. Bench bled and still had to bleed it on the vehicle. I don't believe it's unusual at all to have to do it. Up to you but it could save you from doing extra work.

Thanks not a bad idea and would not take long. I will give it a try and let ya'll know if it works. Thanks for all the help so far!

No problem at all.

You may have checked this already but do you have the rear drums exposed so you can make sure your wheel cylinders are good while you're at it? I don't remember having too much trouble and bench bleeding the M/C is recommended (like you did) before you put it on the Jeep. Any chance a hydraulic hose is on the way out? Sometimes they look good and once the power is put to them they can blow up like balloons.