Not Camaro, Explorer rack and pinion question

I'd like to hear anyones suggestions that have any experience replacing power steering rack and pinions. I recently did this on a 96 Ford Explorer we've owned for over 12 years. The vehicle served us well, put my son through 4 years of college. This one however has me scratching my head because after I was finished the vehicle commands full left turns uncommanded and eventually took on a very violent half turn left, half turn right so quickly that you hardly see the spokes in the steering wheel. When it went full left into the stops I could not physically turn the wheel off the stop back to nuetral, the hydraulics weren't going to let me win!

There was no air in the system, I bled it at the rack fittings (6), pump return, pump outlet, cooler and primed the system prior to starting it. The fluid returning to the pump was not aerated when this problem was occuring. I installed a new power steering pump, cooler, rack and pinion, rod ends and cleaned/flushed the pressure and return hoses. The steering wheel was NOT turned after the old rack was removed until after the new rack was connected to the intermediate shaft. The Ford service manual suggests centering the wheel prior to removal of the rack, but this is imposible because the rack will not come out of the frame cross members unless you remove the boots, slide them out of the way, turn the wheels all the way to the right so the rack will clear the cross member and remove the drivers side inner and outer tie rod assembly from the rack. I measured the rack protruding from each end of the housing with calipers and set up the new one to the same dimension and the intermediate shaft lined up perfectly because I never moved the steering wheel, so the clock spring would not be damaged. Primed and bled everything and the thing just wants to turn to the left, then the very violent back and forth swinging of the steering wheel.

I've decided to scrap out the car. I can't in good conscience ever put my family, or my son's family (we'd given him the car) in this car ever again. Just a really strange problem. Not all is lost because I swapped all the newer items from the 96 to my 00 Explorer before scrapping the 96 (battery, starter, wheel bearings, calipers, rotors, pads, tires, ect). Most of those items are only a couple months old.

Just wondering if anyone else has ever encountered such behavior after a rack and pinion swap. Air in the system is the only thing I could think of unless the rebuild of the unit is suspect. It was delivered without the restrictor in the return port, which I swapped over from the old unit.

Had the same issues exactly in a 1993 Aerostar awd van after a rack and pinion replacement. It ended up being air. I bled the damn thing over 5 times and it took weeks for the problem to finally go away. I too was pulling my hair out but in the end it was air.

Alex thanks for the reply. After reading it I decided I'd give it another try to see if I could get the steering working. Thought if I could fix everything I'd give it to my nephew, he needs a car. After filling the PS pump reservoir again I noticed right away that the fluid was running right out the top of the rack and pinion input shaft seal, where the intermediate shaft attachs. So the rack must've blown a seal when the steering wheel did it's violent left/right movements. Probably was air causing it like you suggest. I'm not going to go to the trouble of changing the rack again, at least not right now. Maybe I'll feel differently in a week or so if I still have the vehicle then.

I'm also a little concerned about the rebuild on the rack. A company in Canada rebuilt it. the first one shipped with the wrong rack, an Aerostar or Windstar rack in a Box labeled for an Explorer. The second one came in with the wrong input shaft. Third one was right, but blew the seal and didn't have the restrictor installed in the return side of the rack (I caught this before installation and dropped the restrictor into the port just like it was in the old unit). Fair to say I haven't had a good experience with this repair vendor. As you know this isn't a simple task to change out the rack, not much room to work and you've got to reassemble it once it's bolted into the crossmember.

Thanks again.