Full Size Jeep Network

Had fully functional brakes with vacuum booster no problems before upgrade.
Installed a hydroboost from BJs. Brake pedal has a very short amount of normal travel, then it gets rock hard. I can push through the hard spot, then hydraulic pressure starts pushing back against me I can feel in pulsing in the pedal along with the pump. Overall have a very short pedal travel. I haven't tried to drive it yet. I have owned multiple hydroboost vehicles including my current DD, so I know what a proper working system should feel like.

Any ideas on what could cause this? I am going to try looking at a chevy factory service manual for troubleshooting.

Went back out to garage decided to try it with the engine reved up. Still have same hard pedal feel but almost immediately got the pump to start screaming. Shut it down and checked, fluid is all aerated. Will let it sit over night. I have only been testing at idle, possibly I didn't get all the air out of the booster.

Check your hose routing as well. Getting all the air out takes time and can be frustrating. Best thing I have found is start it and let it run for a while, sometimes over an hour, occasionally pressing the brakes and steering the wheel lock to lock. Check the fluid once it running and make sure it has fluid. Fluid level changing more than 1/2” from not running to running indicates air in the system.

I'm with Yeller check pressure return routing , usually run the HB return directly to the pump and tee the PS box return line into the HB return line, better would be a PS resv with two return ports.
The LM7 (04 tahoe) in my J10 has two return ports in the reservoir from the factory.

Thanks for the replys. I believe I have the pressure hoses in proper location. I used my chevy truck as reference.

I for sure still have air in the system. I started it again this morning before I went to work and it quickly aerate the fluid again. I will start over on the bleeding thought I had all the air out I obviously do not.

I guessed at reservoir with two return fittings but guessed wrong it won't fit in the stock bracket. Still need to modify to make work. I will check out an 04 tahoe. I may plumb in something temporary with a hose through the filler just for garage testing.

Until then What is proper routing for the T? I have return from the box and return to reservoir straight in line. The return from the hydro boost comes into the T at the 90degree angle from the steering box return.

The tee goes in the return line near the reservoir.

A trick I learned years ago bleeding full hydraulic steering systems is to fill the reservoir, start the engine and immediately add fluid until it appears to be just a bit over the “full” level before being started. Let it run, every few minutes step on the brake pedal and steer lock to lock checking the fluid level after each procedure. Do this until the pump is quiet while your doing other tasks. Once you shut the engine off if the reservoir overflows you still have air in the system, repeat. Even take it for a test drive if you can.

Got it fully bleed no improvement. Eliminated the T ran both returns independent into reservoir (no back pressure on return) no improvement. Replaced power steering pump with brand new pump for hydroboost application no T two returns no improvement. All the air is out. Pedal travels very short distance then gets rock hard, can push through that hard spot, can feel pedal go past hard spot then hydraulic pressure is pushing back at me. Booster has to be bad, hopefully BJs will take make this right.

BJs only open Monday-Thursday, and website says they are off next week. Not good.

To clarify my last post. I don't have a problem with bj being closed. What I ment was not looking good for me having working hydro boost on upcoming trip.

Just to make sure, have you checked the angle of the rod as the pedal depresses? If the angle is wrong it will hit and prevent you from fully depressing.

will look tomorrow. thanks

Assuming Kit from BJ's came with the right spacer only thing left is the hydroboost itself , I had a BMW with HB years ago the accumulator failed and vaguely remember pedal petal hard as rock