Buick Repair Questions? Ask a Mechanic for Answers ASAP
Are you getting any noise from the power steering pump?
Does the fluid look bubbly?
Was the system bled after replacing the rack?
Do you have a fluid pressure gauge set?
To test the pump you will need a flow/pressure gauge set:
Install the power steering pressure/flow gauge on the power steering high pressure line. Start the engine and bring it to operating temperature. Turn the steering wheel and BRIEFLY hold the steering wheel against the steering stop in order to release any trapped air from the system. Making sure the steering wheel is OFF the steering stop, observe the pressure reading. Normal pressure reading is less than 230 PSI.If the pressure is less than 230 PSI, record the pressure reading and flow reading. Partially close the valve on the pressure/flow gage until the system pressure reaches 700 PSI, then record the FLOW reading.If the flow decreases greater than 1 gal per minute, replace the power steering pump.If the pressure and flow reading are within specification, fully close then open the power steering pressure/flow valve 3 times and record all of the high pressure readings. Refer to power steering pump specifications for this vehicle for power steering system pressure relief specifications.If the 3 high pressure readings are not within 50 PSI of each other, replace the power steering pump.
New pump, new rack and still no power assist? Does this model have the variable assist orifice?
Nothing in the suspension seems to be binding and making it feel like the power steering isn't working right? Over tightened tie rod ends or something?
You could try disconnecting both tie rod ends from the steering knuckles and then try turning the wheel, if the steering feels normal then something in the steering linkages is binding.
Did you bleed the system with a vacuum bleeder?