Auto Repair: How to Use a Jack Safely


The most obvious reason to jack up a car is to change a tire, but other jobs such as inspecting brakes may also require you to get under the vehicle. (Even if you're skinny enough to squeeze yourself between the pavement and the underside of your car, you still need room to move around and manipulate tools.) This section explains how to use a jack safely and efficiently.

Caution: Before you attempt to jack up your vehicle, observe the following safety precautions:

  • Jacks are used only to get a vehicle off the ground. They should never be used to hold a vehicle in place.
  • You must use jack stands when you work underneath your vehicle. If you don't, you run the risk of serious injury or even death. People have been crushed to death when vehicles that were improperly secured fell on them.
  • Never jack up a vehicle without blocking the wheels to keep it from rolling. Use bricks, wooden wedges, or metal wheel chocks to block the wheels at the opposite end of the car from the end that is to be raised. (Chocks are available at a low cost at auto supply stores.) Keep whatever you use for blocks in the trunk so that you don't have to go hunting around if you have to change a flat tire.

Tip: If you find yourself faced with the job of changing a tire and you have nothing with which to block the wheels, park near the curb with the wheels turned in. This may not keep you from getting hurt if the car rolls off the jack, but at least innocent motorists and pedestrians won't have to deal with a runaway driverless vehicle!

Never change a tire on a freeway or highway. Not only can you be seriously injured, but you can also fall prey to carjackers. Don't exit the vehicle; instead use a cellphone to call road service or an automobile association such as the AAA. If you don't have a cellphone, hang a white rag or a white piece of paper out of the driver's side window and wait for the highway patrol to rescue you.

CarSmarts: Even if you hate cellphones, I recommend that you buy one and keep it in the vehicle for emergencies. You can find a very affordable model that just lets you call 911, road service, and those you'd want to notify in an emergency. It could save your life.

Always park a vehicle on level ground before you jack it up. If you get a flat tire on a hill and can't coast to the bottom without killing the tire completely, park close to the curb, turn the wheels toward the curb, and block the downside wheels securely to prevent the car from rolling.

Remember: These precautions won't eliminate the risk of changing a tire on an incline. If you can't get to level ground or wait for assistance, you change the tire at your own risk.

Be sure that your gearshift is in Park (or in First if you have a manual transmission) and that the parking brake is on before you jack up the vehicle. The only time you don't want the parking brake on is when you have to be able to rotate a rear wheel or remove rear brake drums to inspect the brakes. In such a case, make sure that the front wheels are blocked securely.

Caution: If you remove a wheel and begin to work without making sure that you jacked up the car and blocked it securely, the vehicle can do a lot of damage to itself -- and to you -- if it falls. (This is not meant to frighten you away from jacking up your car and working on or under it. It's just to emphasize the fact that taking a few simple precautions can keep you safe.)

After you've observed all the safety precautions, follow these steps to jack up a vehicle:

1.  If you're going to remove a wheel to change a tire or check your brakes, remove the wheel cover or hubcap (if there is one) and loosen the lug nuts.

After the vehicle is jacked up, the wheel will turn freely, which makes it harder to get a wheel cover off and almost impossible to start turning the nuts. Instructions for removing a wheel cover and loosening lug nuts are in the next section, "How to Change a Tire."

2.  Place the jack under the part of the vehicle that it should contact when raised. If you're using jack stands, place them near the jack.

Where you place your jack depends on whether you're planning to do a one-wheel job, such as tire changing or brake checking, or a two-wheel, whole-end repair job. Many vehicles now have special flat spots on the underside specifically for jack placement.

Tip: If you place your jack incorrectly, you can injure your car. To find the proper place to position the jack for your particular vehicle, check your owner's manual. If you don't have a manual, ask the service department at your dealership to show you the proper placement. In any event, follow these guidelines:

  • Never place the jack so that the weight of the vehicle rests on something that can bend, break, or give.
  • If your manual is incomprehensible or lacks jack placement information, try to place the jack so that it touches either the vehicle's frame or the big bar that supports the front wheel suspension.
  • You can also place jacks near the rear-wheel axle, but until you become more proficient at this, I'd stick to jacking up one wheel at a time.

3.  Lift the vehicle by using the jack. How you accomplish this depends on the type of jack you're using (see Figure 1-1):

  • If you have a scissor jack, insert the rod or wrench over the knob, and then crank.
  • If you have a hydraulic jack, place the handle into the appropriate location and pump up and down. Use nice, even strokes, taking the jack handle from its lowest point to its highest point on each stroke to cut down on the labor involved.

auto repair figure 1-1

4.  Place the jack stands under the vehicle, near where the jack is touching it (see Figure 1-2). Raise the stands until they're high enough to just fit under, and lock them in place. Lower the jack until the vehicle is resting on the jack stands.

auto repair figure 1-2

Caution: Substituting boxes, stones, or bricks for jack stands is very dangerous. They can slip out or break while you're under the car. A jack can do the same thing, so be sure to buy a pair of jack stands and stow them in the trunk if you're traveling out of reach of help if you get a flat tire.

5.  Before you begin to work, wiggle the vehicle a little to make sure that it's resting securely on the jack stands. Then remove the jack.

Wiggling the vehicle also tells you whether you have the wheels blocked properly. It's better if the vehicle falls while all four wheels are in place. (It will bounce just a little.)

6.  When you're finished working, replace the jack, remove the stands, and lower the vehicle to the ground.

If you're using a scissor jack, simply turn the crank in the opposite direction. If you're using a hydraulic jack, use the rod to turn the pressure release valve. The jack will do the rest of the work for you.

From Auto Repair for Dummies, copyright © 2009 by Wiley Publishing, Inc., Indianapolis, Indiana. Used by arrangement with John Wiley & Sons, Inc.

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