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Maintenance Check: Under the Hood
By Wayne Scraba/
Printable version
Degree of DifficultyEasy
Estimated Time120 minutes
120 minutes
Pre-Flight Safety Inspection for Your Car or Light Truck-
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 lack-of-maintenance induced car trouble, especially when you find yourself stuck between middle and nowhere. What follows here is a list of “pre-flight,” underhood 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):
Under the Hood Maintenance 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, 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. If the level is on the “Add” line (some late model dipsticks have a cross-hatch area near the tip, indicating the “Add” mark), you’ll have to add approximately one quart. Low oil levels can only mean two things: The engine is burning oil or it is leaking oil. In either case, it’s a good idea to have the car inspected by a mechanic.
Oil level checks are critical. Typically, the dipstick is marked or color coded as shown here.
Check the Engine Oil
When adding oil, add the same type, brand and weight you normally use in the engine. If you don’t know the oil specifics, check the owner’s manual. Additionally, following an oil change, you’ll often have a sticker affixed to the car, indicating the oil specifics. The sticker could be made of paper and attached in a conspicuous spot under the hood or on a doorjamb. It can also be transparent and affixed somewhere to the vehicle windshield. Do not add too much oil! If there is too much oil in the engine, damage can occur.
Transmission Fluid
There are two major types of transmissions used in vehicles today (and in the past): Automatic and manual. Almost all automatic transmissions have dipsticks and allow for fluid checks. Almost all manual transmissions do not have dipsticks, and do not have easy provisions to check fluid levels.
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.
Check the Automatic Transmission Fluid
To check the fluid level in an automatic, the transmission must be at operating temperature (typically in the 180°-200° 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 3-4 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 of the way back in. Wait 3-4 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).
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