Hard brake pedal after I did heatercore.

[SWilliams]

The pedal getting harder as you drive isn't going to be the parking brakes. Even if they were dragging they cannot self apply. However a bad master cylinder or rubber line can cause this as both can block fluid return to the reservoir. This will cause the hard pedal because the fluid expands and as it does it applies the brakes at both ends and also pushes the piston in the master cylinder back harder. From the description and the way the rear brakes are the ones locking up (you didn't mention the fronts being a problem) I would look at the front system first, the reason being that if it was a bad rear flex line, the rear brakes would apply, but because the hose is between them and the master cylinder the fluid pressure won't get to the master cylinder and cause it to get hard. So that leaves the front brake system with a bad master cylinder being the most likely. The next step is to drive it until the brakes get stiff, now go to the brake lines and crack the lines just until fluid leaks out. Do the brakes release? If yes it's a bad master cylinder.

 

[gbennett21]

Thank you guys for the response what i will do is replace calipers on rear. The pistons are showing signs of rust also I just feel like its a good time show son how to do those. I will update you guys tomorrow if that fixes it. You guys have been a big help. so if i run into same thing we can bounce ideas of each other.

 

[gbennett21]

update guys so i put on new rotors pads and calipers. bleed new calipers.2 man method what i noticed is when my son had his foot on brake pedal to push air out rear passanger side was easy to get air. driver side which is the side i belive was causing the problem i notice he would have his foot down on pedal and i have bleeding ***** open fluid would start coming out then stop. is that supposed to act that way or is the fluid supposed to just keep coming out the whole time his foot has pedal down. So i did the best i can on that side to bleed them out. we drove the jeep and it runs great its actually more responsive now on the gas pedal. brake pedal is not as hard as it was but it stops good just not sure if the new feel is what they call spongy brakes or not. not sure what im looking for on that. but i belive all air is out. Now back to my original reason this all occurred new heater core and blend door do work i can see it working (from a cut hole in the hvac box) but still no heat if i pump heater hoses i can get the hoses to warm up some. I can tell heater core is not getting hot enough ive been trying to burp this system along time i have flushed and refilled this system at least 5 times some times i can get some heat but not enough to be effective but after the new heater core i haven't been able to get it burp it seems. tried on ramps tried big funnels on top of refill tank . let it idle for 30min with bleeder open some. i even let it run 1.5hr and press gas every now and then.jeep never gets past the half way mark on temp gauge. just lost put in 2 thermostats now im going to try a mopar one. also made sure jiggle valve is at 12 o'clock. But as I said runs great now, and thank you

 

[DadOSix]

Fluid should not keep flowing while the brake pedal is down.

Our method was:

Make sure master cylinder is full of fresh fluid. Do not used recycled fluid. Cap master cylinder.

Pump brake 3 times and hold pedal.

Partner opens bleeder and watches fluid and air come out. Preferably thru a hose into a clear jar.

Brake pedal should be on the floor.

Close bleeder and have in car partner let foot off the brake.

Pump it up again.

Repeat a few times til no air.

Check master every 3rd or 4th time and top off as needed.

If it feels spongy or springy, there may still be air.

You SHOULD bleed all 4 calipers, starting furthest from master cylinder anytime you replace a caliper.

Air can and does travel toward the master when a caliper or hose is removed.

Air in the line can allow the fluid to ‘boil’ in a high temperature situation, leaving your son with no brakes.

 

[DadOSix]

On the heater - burp, etc:

Are you certain there is water coming out of the hoses feeding the heater core?

Given the arrangement of that heater hose setup - reminds me of a trombone - there could be a restriction there. I’ve never had that issue. Not sure how i would move forward, except for removing the hose at the core and directing to a bucket or similar to assess flow. Have your helper start the car briefly while you catch the fluid.

 

[JeepJeepster]

Yes, the brake fluid should spit out some then stop.

If you have the coolant bleeder ***** removed, coolant should be spilling out all over since the place since the coolant reservoir is higher than the bleed *****.