Skip to main content
Skip to page content

Car maintenance checklist: Under the hood

Car maintenance checklist for under the hood The road beckons. It’s the thrill to see what’s around the next curve or over the next hill. It’s adventure, pure and simple. But what about the health of your car or light truck? The last thing you need is car trouble induced by lack of maintenance, especially when you find yourself stuck between middle and nowhere. What follows here is a list of “preflight,” under-hood checks you should accomplish before turning the key and hitting the road. Check it out. It’s important (and by all means, consult your vehicle’s owner’s manual).

Check engine oil
It is important to check the oil level in your vehicle engine on a regular basis. It’s also important to keep the level at a satisfactory point. Checking the oil level is not difficult, and most manufacturers suggest you check the oil every time you gas up. In order to get an accurate reading, the oil must be warm, and the vehicle must be parked on level ground. With the engine off, but warm, allow several minutes for the oil to drain back into the sump. Locate the dipstick (typically colored and/or marked “OIL”). Pull it out and wipe it off with a paper towel or cloth. Push it back in all the way, then remove it again and inspect the level while keeping the tip down. The idea here is for the oil to be on or very near to the “Full” line. If the level is on the “Add” line (some late model dipsticks have a cross-hatch area near the tip that indicates the “Add” mark), you’ll have to add approximately 1 quart. Low oil levels can only mean two things:

  • The engine is burning oil, or
  • The engine is leaking oil.

In either case, it’s a good idea to have the car inspected by a mechanic.

Check engine oil level with dipstick The automatic transmission fluid should also be checked. In many late model vehicles, the dipstick has a lock on the handle that must be flipped before checking the oil level.

To check the fluid level in an automatic, the transmission must be at operating temperature (typically in the 180-200 degrees Fahrenheit range). If the vehicle is cold, drive for approximately 15 miles before checking the fluid. Park the vehicle on level ground and apply the park brake. With your foot on the service (normal) brake, move the shift lever through each gear range (Reverse, Neutral, Drive, Drive 3, Drive 2, Drive 1 and so on). Pause for 3 to 4 seconds in each gear range. Shift the car into Park. Allow the engine to idle for several minutes. Without shutting off the engine, locate the transmission dipstick. Typically, it is clearly marked and/or color-coded, often with the words “Transmission” on the handle. If equipped with a handle lock, flip it “up” and then remove the dipstick. Wipe the indicator with a paper towel or clean rag. Push the dipstick all the way back in. Wait 3 to 4 seconds and pull out the dipstick again. Check both sides of the dipstick. Typically, you’ll need to examine the “Hot” section (or the cross-hatched area of the dipstick). Keep the dipstick pointing down to get an accurate reading. The fluid level should be in the acceptable range (“Hot”). If so, push the dipstick all of the way back in the tube. If equipped with a lock, flip it closed. It’s a good idea to physically check the fluid twice, especially if it appears that the transmission needs more fluid.

To add fluid, you must first determine the type of fluid your car or truck uses. Your owner’s manual will provide you with the automatic transmission fluid specifications required by your vehicle. Do not mix and match fluid types! Do not overfill. To physically add fluid, most cars mandate the fluid be poured in through the transmission dipstick tube. A small funnel is needed to accomplish this. Generally speaking, a transmission that is low on fluid will not require much in order to bring the level to the “Hot” mark on the dipstick (typically a pint or less).

How to check coolant level
Modern vehicles do not mandate the removal of the radiator cap in order to check the level. In fact, radiator caps today are designed to be difficult to remove. The coolant level is checked by way of the surge tank, often mounted on the inner fender in close proximity to the sealed radiator cap. To check the fluid, the vehicle must be on level ground. Preferably, it should be “cold.” In most cases, the surge tank is transparent and will be marked with the letters “FULL COLD.” You can physically see the level in the tank.

Check coolant level in surge tank

To check the coolant levels on most vehicles, you simply examine the level in the surge tank (as shown here). There is no need to remove the radiator cap.

If you need to add coolant, first check the specifications in your owner’s manual. Do not add water alone as most vehicles today mandate some form of coolant blend. In most cases, coolant is added to the surge tank. Again, do not overfill.

If the car is older and is not equipped with a surge tank, wait until the engine has cooled before opening the radiator cap. Turn the cap slowly to the left until it reaches a “stop.” Don’t press down on the cap. Wait a minute or so before proceeding. If you hear a hissing sound, pressure is being relieved. Once the hissing sound stops, press down on the cap and continue to turn to the left. Fill the radiator to the base of the filler neck. Start the engine. With the engine idling, add coolant to the radiator until it reaches the bottom of the filler neck. Reinstall the radiator cap. In many cases, there are two arrows on the cap. In those instances, ensure the arrows on the cap line up with the radiator overflow tube (on the radiator filler neck).

In either case, be careful with coolant as most blends contain ethylene glycol. It will burn if spilled on very hot external engine components (for example, exhaust manifolds).

How to check brake fluid level
Early cars mandate you remove the fluid cap (or caps) in order to inspect the brake fluid level. Always clean the reservoir cap and the area around it prior to removing it. This helps to prevent dirt and debris from entering the brake fluid master cylinder reservoir. In some cases, you will have to remove one or two “bail wires” that affix the cap to the master cylinder. Typically, you simply pry the bail wires to one side with a screwdriver. Once the cap is removed, you will sometimes be faced with removing a large rubber seal (in most cases, it will remain in the cap). At this point, you can physically inspect the fluid level.

Check brake fluid level in translucent plastic master cylinder

Brake fluid levels are also easy to check on most vehicles. The master cylinder fluid levels are typically made of a translucent plastic material, allowing easy inspection.

On later model vehicles, the reservoir is transparent. You can inspect fluid levels without removing the cap. Typically, the reservoir is marked “MINIMUM” and often with “MAXIMUM” as well. Fluid should not be over the maximum and obviously should not be below the minimum.

There are only two reasons why the brake fluid level can go down:

  • The first reason is normal wear. As the brake pads (disc or drum) wear, the fluid level in the hydraulic system goes down. If new linings are installed, then the fluid level will go back up.
  • The other reason is a leak. If the system is leaking, stop! Do not drive the car. You should contact a mechanic as soon as possible to determine the cause.

Before adding fluid, check the owner’s manual to determine the brake fluid specifications for your particular vehicle. Using an incorrect fluid can damage the hydraulic system parts within the brake system. When adding fluid, pour it into the open reservoir slowly – you really don’t want air bubbles to enter the hydraulic system. Be very careful with fluid. If you spill fluid on the vehicle’s finish, paint damage can (and most often will) occur. Wash the fluid off with cold water immediately.

Car battery sealed and no maintenance required

How to check battery condition
Sealed, maintenance-free batteries have been in use for a number of years. Obviously, they require no maintenance and have no filler caps, and you never need to add water. Many of these batteries have some form of test indicator (in essence, a built-in hydrometer) located on the top. Most will show a “green” color if the battery is in good working condition. If the hydrometer or test indicator is black, then the battery is discharged. A discharged battery is an indication that it needs replacement or there is a defect in the charging (alternator) system.

Most batteries in use today need no service. Many (such as this) do not have removable caps; they’re factory sealed.

Inspect car air filter element under filter housing cover

Check car air filter
Most vehicles use some sort of disposable paper type element. There are a number of air cleaner/air filter arrangements in use today. Follow the owner’s manual to determine how to gain access to the element. Once the element has been removed, lightly shake it to remove dust and dirt. Do not wash, oil or clean with an air hose. If the air filter element has dirt caked on, a new element is required. Today’s vehicles do not require overly frequent air filter element changes unless used in very dusty conditions. Some vehicles are designed with filters that only have to be changed after 50,000 miles. 

Certain vehicles (for example, pickup trucks) are often equipped with “air filter restriction indicators.” These devices are usually located on the air cleaner/filter cover. If the indicator has turned to black or is in the “red” or “replace” zone, it’s time to service the filter.

Air filters too are now of the high mileage variety. To inspect the element, you have to remove the filter housing cover.

Check power steering under cap of power steering reservoir

How to check power steering
It is not necessary to check the power steering fluid unless you suspect there may be a leak in the system. If the fluid is leaking, you must have the system serviced by a mechanic as soon as possible. The power steering reservoir (often marked “POWER STEERING” on the reservoir cap) is either found directly on the steering box or rack or remotely mounted very close to it, most often on the driver side of the car. The reservoir will have a removable dipstick tube. Unscrew the reservoir cap to access the fluid. In most cases, the reservoir cap will contain an integral dipstick. Before checking, determine if the fluid is hot or cold. Typically, if the fluid reservoir is hot to the touch (approximately 150 degrees Fahrenheit) then you’ll have to look for the “hot” marks on the dipstick. If cold, then refer to the “cold” marks on the dipstick. Pull it out and wipe it off with a paper towel or cloth. Reinstall all the way (which means turning the cap to the right). Remove it again, keeping the tip down, and inspect the level. The idea here is for the oil to be on or very near to the “Full” line (“Full Hot” or “Full Cold”). If the level is on the “Add” line, you’ll have to add a small amount of fluid. You must use the appropriate fluid (type specified in the owner’s manual). This fluid does not require periodic changes.

Power steering reservoirs can either be mounted directly on the pump (as shown here) or remotely mounted. There is usually a dipstick under the cap.

Check windshield washer fluid level through transparent reservoir

Windshield washer fluid
Depending upon the vehicle, the windshield washer fluid is either contained in a transparent reservoir somewhere close to the wiper motor (usually on the driver side of the vehicle) or has a relatively large, clearly marked cap for a hidden reservoir (again, usually on the driver side of the vehicle). To add fluid, you simply unscrew or lift off the cap and pour in the washer fluid. When using concentrated washer fluid, follow the instructions for adding water. Do not mix water with ready-to-use fluid. This degrades the properties of the fluid and may also cause it to freeze in winter conditions. When encountering freezing conditions, many manufacturers recommend you fill the reservoir to only the three-fourths full point to allow for expansion should the fluid freeze. Only use washer fluid. Do not use radiator coolant (antifreeze) since it may cause paint damage and can damage the washer system.

Don’t forget the windshield washer fluid level. Check it by viewing the level through the transparent reservoir.

Two radiator hoses along one serpentine belt

Belts and hoses
Most newer cars require little or no attention to the belts or hoses. However, you should examine them to determine if they are in good working condition. The place to begin is the radiator (located at the front of the car). Be absolutely positive the engine is cold when examining hoses (or belts). Pay close attention to electric cooling fans, as they can operate without the engine operating. These fans function by coolant temperature and are independent from the engine in operation.

Belts and hoses should also be examined. There are two important radiator hoses (an upper and a lower) along with either one long serpentine belt (most common today) or a series of v-belts.

There are two large hoses attached to the radiator, one at the top and another at the bottom. Both lead to the engine. With the engine cold, squeeze each hose. If the hose feels brittle, it's old and needs replacing. Examine each hose for cracks, tears or blisters. If they exist, the hose will need replacement. Next, examine the clamps found on either end of each hose. If the hose is damp or wet in the area of the clamp, tighten the clamp. Each clamp must be sufficiently tight so that the hose cannot be moved (or even turned).

Locate the accessory drive belt(s). They’re located between the front of the engine and the radiator. Visually inspect the belt by turning it (slightly) inside out. In most cases, you will not be able to flip the belt completely, but the belt should allow for a minor “twist” so that you can examine the inside (pulley side). The reason for this is because deterioration almost always begins on the inside of the belt. When examining the belt, look for signs of cracking, fraying or splitting. You should also look for a surface that is hard and appears glazed. The cause of this is long periods of use and high under-hood temperatures. If a belt shows any of the above signs of deterioration, it’s time to have the belt replaced.

Energy lives here