* Improper Rack and Pinion Installation: This is the most probable cause. Even a slight misalignment or improper tightening of the rack and pinion can cause the wheel to move uncontrollably. Double-check the following:
* Tie Rod Ends: Ensure the tie rod ends are properly connected and tightened to the rack and pinion and the steering knuckles. Incorrect adjustment or loose connections here are major contributors to this problem.
* Centering the Rack: The rack itself needs to be centered correctly. There's usually a method to center it during installation; consult your repair manual. An off-center rack will lead to the steering wheel pulling one way or the other, and potentially the wild movement you're experiencing.
* Rack Mounting Bolts: Make absolutely sure all mounting bolts for the rack and pinion are correctly tightened to the specified torque.
* Power Steering Lines: Are the power steering lines properly connected and free from leaks? A leak or improperly connected line can cause erratic behavior.
* Steering Shaft Connection: Verify the connection between the steering shaft and the rack is secure and properly aligned.
* Damaged Rack and Pinion: It's possible the rack and pinion itself was damaged during removal or reinstallation. Internal components could be malfunctioning, causing the erratic movement. This is less likely if the issue started immediately after reinstallation, but still possible if you didn't notice damage earlier.
* Power Steering Pump Problems: While less likely to directly cause the wheel to *move* by itself, a failing power steering pump could cause erratic power assist, making the wheel feel loose or unstable and easier to be moved by other issues.
* Other Steering Components: While less likely given your description, problems with other steering components (like a damaged idler arm or other suspension parts) *could* contribute to this issue if they create excessive play in the steering system.
What to do:
1. Consult a Repair Manual: Get a repair manual specific to your 1989 Mustang. This will provide detailed instructions and torque specifications for the rack and pinion installation.
2. Recheck Installation: Carefully and methodically go back through every step of the rack and pinion installation process. Pay close attention to the points listed above.
3. Inspect for Damage: Look closely at the rack and pinion, tie rod ends, and all other steering components for any visible signs of damage.
4. Professional Help: If you're uncomfortable working on your steering system, or after rechecking everything and the problem persists, take your Mustang to a qualified mechanic. Incorrect steering is extremely dangerous, and professional help is essential.
Safety Warning: Driving a car with this problem is incredibly dangerous. Do not attempt to drive the vehicle until the issue is resolved. The steering wheel moving on its own could lead to an accident.
