Tell

Ok, so I recently bought a 1989 Jeep Cherokee Larado have been tinkering on it. But the issue I have run into is my brakes. So far, I have replaced the front calipers and pads and have put new shoes on the rear. I also put in a new master cylinder.
But every time I press on the brakes, the pedal goes all the way to the floor. If I pump it a few times, it builds up pressure, and I can stop. I have bled the lines 5 times now and have not been getting any air out of them. My cruise control and vent controls don't work either (it only blows air through the defrost vent), so I think it might be a vacuum issue. I am currently pulling 10 inches of vacuum, and I think I should be in the 12-14 range. I also wonder if it might have something to do with the brake booster, but I don't really know.
Any help would be greatly appreciated.
Thanks

agreen

Pull the master cylinder and bench bleed it. The pedal going to the floor is obviously a trapped air issue. Low vacuum would cause a hard pedal. Also, 10" is quite low. You might want to do an engine compression check. But your brakes definitely have air in the lines, so keep working on it. Good luck.

awg

I have had success with some notably difficult vehicles to bleed

starting from the top down, I try & carefully bleed the master cyl and every union I can, mainly using gravity & time to allow the air to find its way out

I do the fronts before the rears (opposite to recommended)

You need minimal assistance but its still tricky as you have to monitor to make sure the resevoir does not run out, plenty of towels around the unions, plastic to protect paint etc etc

BlueRidgeMark

Yeah, turns out brake fluid is a half-decent paint stripper.


When it comes to brake bleeding, Russell Bleeder Valves are your friends.

dale500

Russell Bleeder Valves. I learn something new every time i poke around here. I put those right in the amazon cart

97grand4.0

sinking pedal usually means a fitting still isn't tight, loosing hydraulic pressure and a bit of fluid. recheck. Also have a helper hit the pedal while you look for ballooned hoses.

cruiser54

Here's something to think about:

97grand4.0

True that. A low adjustment on the rear drums will be a low pedal.