I have a 1984 Chevy Caprice with a little problem. I let my 15-year-old son replace a low-beam headlight on the left side. Now the headlight works, but it's pointed up in the air and oncoming drivers are getting a little annoyed. I can tell that by the way they flash their lights at me as they pass. Is there something easy I can do to aim it straight again or should I bring it into the shop?
Take a careful look at the new headlight. Is it securely fastened into its rectangular retainer, and not cockeyed with the screws only half way in? If it was replaced properly it would be aimed exactly where the previous headlight was before it burned out, and no adjustment would be necessary.
If your son accidentally turned one of the two adjusting screws instead of just the four retainer screws, then that's why your headlight is aimed into the sky.
Here's what you can do to fix it. First, locate and identify the screws. There's an adjusting screw on the side of the lamp to aim it side-to-side and a screw on the top to aim it up-and-down. Once you have located the proper adjusting screws, go find some level ground that leads up to a wall or perhaps your garage door. This works best at dusk so you can see the headlight beams and also see what you're doing at the same time. Pull the car straight up to the wall and back up as straight as possible about 20-25 feet.
We will work on the premise that the headlight on the other side is aimed correctly or really close. Turn on the lights, and with the use of the two adjusting screws, we can line up the spot where the left beam hits the wall in proportion to the right beam. Adjust it so the left spot is the same height off the ground as the right, and also the same distance in from the outside of the fender. If both your lights were out of whack you could compare to a known good vehicle.
There are several methods of headlight aiming used by repair shops. The wall method in a designated location is probably the most popular. There are also expensive aiming tools that mount directly to the headlamp lens. More and more of today's new cars are incorporating "bubble gauges" as a part of the headlamp lens itself. This makes aiming that much more convenient.