Jeff's DIY

Advice on doing your own diagnosis and repair

Advice from the book Can I Do It Myself?


Basic DIY Auto Maintenance

Use your owner's manual for help with the most basic maintenance items.

Checking Fluids

The following are fluids common to most automobiles:

Oil: may be brown or black. Leaks may appear under the engine and in some trucks by the radiator. The level is checked using the dipstick near the center of one side of the engine. Oil is added through a cap or filler tube connected to one of the valve covers on top of the engine. An engine low on oil may have a ticking sound or low oil pressure indication. Shut off the engine immediately if you experience either of these symptoms.

Coolant: may be yellow or purplish. Leaks may appear under the engine, on the passenger-side floorboard, or under the middle of a vehicle that has a rear auxiliary heater. The coolant level is usually checked in a white plastic reservoir under the hood. There are full level marks on the side that indicate the appropriate level for hot or cold engines. An engine low on coolant may have an indication on the dash, overheat, or have a poorly functioning heater. Do not run the engine hot, or severe damage may occur. Some foreign engines have bleed ports on the thermostat housing or along the upper radiator hose that should be opened to release air when filling the cooling system. To drain and replace the coolant, look for a petcock or plug under the radiator. If there is no drain port, loosen the lower radiator hose at the radiator to drain the coolant. Water vapor on the windshield or coolant smell in the car indicates a leak in the heater core. A small leak may only fog the glass, but a larger one will leak on the floorboard. The leak may be temporarily fixed by looping one of the heater hoses between the high and low pressure ports of the engine. This will disable the heater until the core can be replaced.

Automatic Transmission Fluid: may be purple or dark purple. Dark fluid should be replaced professionally. Leaks may occur under the transverse engine or under the middle front a rear-wheel or four-wheel drive vehicle or possibly near the radiator. The level is checked with the engine idling using the dipstick usually on the right side of a transverse engine or in the back of a rear-wheel drive vehicle. Fluid is added using a funnel in the dipstick tube. A transmission low on fluid may not shift into gear. Do not rev the engine to make it engage, as this can damage the flexplate connecting the engine to the transmission.

Power Steering Fluid: is usually clear and leaks will occur near the front or side of the engine. The level is checked by removing the reservoir cap, which generally has a dipstick attached. A pump low on fluid will make a whining noise that is louder when turning the wheel.

Manual Transmission or Differential Gear Oil: is like motor oil but thicker. It may leak under the engine or the middle, or possibly the rear axle in vehicles with rear wheel drive. The level is checked by removing a fill plug from the side. If oil comes out, the level is good. If not, squirt gear oil in until it comes back out. Leaks in these components are rare but will result in a whining noise when the drive train is under load.

Brake or Hydraulic Clutch Fluid: is clear and may leak almost anywhere under the vehicle. The parking brake indicator will usually illuminate when the brake fluid is low. Check the level in the small white plastic reservoir in the right rear of the engine compartment-in front of the driver's seat. If you have experienced braking problems and notice a leak or low fluid level, it is likely the reservoir has allowed air into the lines. In such cases, the leak must be repaired and the system bled before the car can be safely driven. Similarly, a leak in a hydraulic clutch system (manual transmission) will keep you from shifting the transmission.

Checking tire pressure

Normal tire pressures are provided in the Owner's Manual or on the sill of the driver's door. Use a tire pressure gage to check pressures. Always check the pressure in the spare tire as well. Maintaining proper tire pressure is essential to good fuel economy and long tire life.

Changing a flat tire

Always use the Owner's Manual or directions on the jack when available. Make sure the vehicle is on level ground and set the parking brake. Locate the spare and jack and use the lug wrench to loosen the lug nuts one turn each. Make sure the spare has air pressure. In some cases, there may be a hub cap or plastic nut caps to remove before accessing the lug nuts. Place the jack under the vehicle body near the flat tire. Most jacks lift at the pinch weld or other spot just inboard of the wheel well, however, some jacks (recognized by a very long actuating rod) are placed under the axle. Actuate the jack until the tire is off the ground, remove the nuts, and remove the wheel. Additional jacking may be needed to get the vehicle high enough to place the spare tire on the axle. Replace the nuts and tighten as much as possible without the tire spinning or the vehicle rocking on the jack. Lower the jack until the tire touches the ground, and then tighten the nuts using full force on the lug wrench. Remove and stow the jack. If your spare is smaller than the other tires, keep your speed under 50 mph until your tire is repaired and restored to the axle.

Oil Change

An oil change is not difficult, nor does it require a lot of tools; but you can't save much money by doing your own oil change. It is much easier to change the oil on a lift, and the job can be messy at home. I change my oil, but I have a good floor jack and I usually service all four cars in a one hour timeframe. I always change the filters too, because there is a lot of oil in the filter. Before changing your own oil, shop around for deals at your local oil change businesses. If you decide to DIY, find a good deal on oil and filter.

To DIY your oil change, first buy the oil and filter. Make sure to buy synthetic oil if that is what your manual recommends. Some modern engines really DO need synthetic oil. Otherwise just get the correct weight oil. I'm not too picky on filters, but I like the ones that have the rough end that provide a much better grip. Unless your car is high off the ground, you will need a jack and jack stand or a pair of ramps. You will also need a wrench that fits your drain plug, a filter wrench that fits your filter, a drain pan, and a funnel. You can use the jack that came with your car, but jack on the side of the car that is away from the oil pan drain port. That way, you will get more of the old oil out of the engine. Use the jack instructions to raise the car a little more than you need to get under it. Then put your jack stand under and set the height above the frame near the jack. Jack the car until the frame is above the stand, and slide the stand under the frame. Let the jack down until the car is on the frame but leave the jack in place. Identify the oil drain plug and make sure it is not a transmission drain plug. Slide the drain pan under the oil pan and remove the drain plug. The oil will shoot out at an angle, so keep the drain pan more in the direction of the oil flow. Allow the engine to drain until it drips. Replace the plug and tighten. Do not over-tighten. There should be a nylon gasket on the plug to make a seal. Move the pan under the oil filter, remove the oil filter, and hold it over the pan to drain until it drips. Turn it upright and discard according to local laws. Wet the seal on the new filter with old or fresh oil. Check to make sure the old filter gasket is not still stuck to the engine, and spin on the new filter. Tighten according to the instructions on the filter. Use your funnel in the oil fill port to add the recommended amount of oil. Close the fill port and start the engine. Let it run for a minute and check the drain port for a leak. Shut off the engine and check the oil level using the dipstick. Raise the car, remove the jack stand, and remove the jack.

Back to Jeff's DIY

See my book on Can I Do It Myself?

Another book of mine you may be interested in: BYTE YOUR SMALL BUSINESS