CHAPTER 17CHAPTER 17MAINTAINING YOUR MAINTAINING YOUR

VEHICLEVEHICLE

How an Engine WorksHow an Engine Works Your car has a Internal combustion Your car has a Internal combustion

gasoline engine. The engine runs on a gasoline engine. The engine runs on a mixture of gasoline and air.  The ideal mixture of gasoline and air.  The ideal mixture is 14.7 parts of  air to one mixture is 14.7 parts of  air to one part of gasoline (by weight.)  Since part of gasoline (by weight.)  Since gas weighs much more than air, we gas weighs much more than air, we are talking about a whole lot of air are talking about a whole lot of air and a tiny bit of gas.   One part of gas and a tiny bit of gas.   One part of gas that is completely vaporized into 14.7 that is completely vaporized into 14.7 parts of air can produce tremendous parts of air can produce tremendous power when ignited inside an engine. power when ignited inside an engine.

•Your car Engine goes through Your car Engine goes through four-strokes, which are four-strokes, which are Intake, Compression, Intake, Compression, PowerPower and and Exhaust Exhaust. The . The piston travels down on the piston travels down on the Intake stroke, up on the Intake stroke, up on the Compression stroke, down on Compression stroke, down on the Power stroke and up on the Power stroke and up on the Exhaust stroke. the Exhaust stroke.

•IntakeIntakeAs the piston starts down on the As the piston starts down on the Intake stroke, the intake valve opens Intake stroke, the intake valve opens and the fuel-air mixture is drawn into and the fuel-air mixture is drawn into the cylinder (similar to drawing back the cylinder (similar to drawing back the plunger on a hypodermic needle to the plunger on a hypodermic needle to allow fluid to be drawn into the allow fluid to be drawn into the chamber.)chamber.)When the piston reaches the bottom When the piston reaches the bottom of the intake stroke, the intake valve of the intake stroke, the intake valve closes, trapping the air-fuel mixture in closes, trapping the air-fuel mixture in the cylinder.the cylinder.

• CompressionCompressionThe piston moves up and compresses The piston moves up and compresses the trapped air fuel mixture that was the trapped air fuel mixture that was brought in by the intake stroke. The brought in by the intake stroke. The amount that the mixture is amount that the mixture is compressed is determined by the compressed is determined by the compression ratio of the engine.  The compression ratio of the engine.  The compression ratio on the average compression ratio on the average engine is in the range of 8:1  to 10:1.engine is in the range of 8:1  to 10:1.This means that when the piston This means that when the piston reaches the top of the cylinder, the reaches the top of the cylinder, the air-fuel mixture is squeezed to about air-fuel mixture is squeezed to about one tenth of its original volume.one tenth of its original volume.

• PowerPowerThe spark plug fires, igniting the The spark plug fires, igniting the compressed air-fuel mixture which compressed air-fuel mixture which produces a powerful expansion of the produces a powerful expansion of the vapor.  The combustion process pushes vapor.  The combustion process pushes the piston down the cylinder with great the piston down the cylinder with great force turning the crankshaft to provide force turning the crankshaft to provide the power to propel the vehicle. Each the power to propel the vehicle. Each piston fires at a different time, piston fires at a different time, determined by the engine firing order. By determined by the engine firing order. By the time the crankshaft completes two the time the crankshaft completes two revolutions, each cylinder in the engine revolutions, each cylinder in the engine will have gone through one power stroke.will have gone through one power stroke.

• ExhaustExhaustWith the piston at the bottom of the With the piston at the bottom of the cylinder, the exhaust valve opens to allow cylinder, the exhaust valve opens to allow the burned exhaust gas to be expelled to the burned exhaust gas to be expelled to the exhaust system.   Since the cylinder the exhaust system.   Since the cylinder contains so much pressure, when the contains so much pressure, when the valve opens, the gas is expelled with a valve opens, the gas is expelled with a violent force (that is why a vehicle without violent force (that is why a vehicle without a muffler sounds so loud.) The piston a muffler sounds so loud.) The piston travels up to the top of the cylinder travels up to the top of the cylinder pushing all the exhaust out before closing pushing all the exhaust out before closing the exhaust valve in preparation for the exhaust valve in preparation for starting the four stroke process over starting the four stroke process over again.again.

Oiling SystemOiling System • Oil is the life-blood of the engine. An engine Oil is the life-blood of the engine. An engine

running without oil will last about as long as running without oil will last about as long as a human without blood. Oil is pumped a human without blood. Oil is pumped under pressure to all the moving parts of under pressure to all the moving parts of the engine by an oil pump.  The oil pump is the engine by an oil pump.  The oil pump is mounted at the bottom of the engine in the mounted at the bottom of the engine in the oil pan and is connected by a gear to either oil pan and is connected by a gear to either the crankshaft or the camshaft.  This way, the crankshaft or the camshaft.  This way, when the engine is turning, the oil pump is when the engine is turning, the oil pump is pumping.  There is an oil pressure sensor pumping.  There is an oil pressure sensor near the oil pump that monitors pressure near the oil pump that monitors pressure and sends this information to a warning and sends this information to a warning light or a gauge on the dashboard. light or a gauge on the dashboard.

Engine CoolingEngine Cooling • Internal combustion engines must Internal combustion engines must

maintain a stable operating maintain a stable operating temperature, not too hot and not too temperature, not too hot and not too cold.  With the massive amounts of cold.  With the massive amounts of heat that is generated from the heat that is generated from the combustion process, if the engine did combustion process, if the engine did not have a method for cooling itself, it not have a method for cooling itself, it would quickly self-destruct.  Major would quickly self-destruct.  Major engine parts can warp causing oil and engine parts can warp causing oil and water leaks and the oil will boil and water leaks and the oil will boil and become useless. become useless.

Ignition SystemIgnition System

Under hood checksUnder hood checks

• Engine oil levelEngine oil level

• Transmission fluidTransmission fluid

• Brake fluidBrake fluid

• Power steering fluidPower steering fluid

• Coolant (Antifreeze) levelCoolant (Antifreeze) level

• BatteryBattery

• Windshield washer solventWindshield washer solvent

• Belts & HosesBelts & Hoses

• Engine oil levelEngine oil level To check the oil level, To check the oil level, make sure that the engine is turned off, make sure that the engine is turned off, then find the engine oil dipstick and then find the engine oil dipstick and remove it. With a paper towel or rag, wipe remove it. With a paper towel or rag, wipe off the end of the stick and notice the off the end of the stick and notice the markings on it. You will usually see a mark markings on it. You will usually see a mark for "Full" and another mark for "Add." for "Full" and another mark for "Add." Check your owners manual to be sure. Check your owners manual to be sure. Push the stick back into the tube until it Push the stick back into the tube until it seats then immediately pull it out to see seats then immediately pull it out to see the oil level. You should not add oil unless the oil level. You should not add oil unless the level is below the "Add" mark and the level is below the "Add" mark and NEVER add oil to bring the level above the NEVER add oil to bring the level above the "Full" mark. "Full" mark.

• Transmission fluidTransmission fluidMost automatic transmissions should Most automatic transmissions should be checked while the engine is be checked while the engine is running. Check your owners manual to running. Check your owners manual to be sure. Also make sure the car is on a be sure. Also make sure the car is on a level surface and fully warmed up. Pull level surface and fully warmed up. Pull the transmission dipstick out, wipe off the transmission dipstick out, wipe off the end and note the markings on the the end and note the markings on the end of the stick. The usual markings end of the stick. The usual markings are "Full" and "Add 1 pint." Push the are "Full" and "Add 1 pint." Push the stick into the tube until it seats, then stick into the tube until it seats, then immediately pull it out to see the fluid immediately pull it out to see the fluid level. Transmission fluid should be pink level. Transmission fluid should be pink or red in color with the look and or red in color with the look and consistency of cherry cough syrup.  If consistency of cherry cough syrup.  If the fluid is a muddy brown or has a the fluid is a muddy brown or has a burnt smell, have it checked by a burnt smell, have it checked by a mechanic.mechanic.

• Brake fluidBrake fluidThe brake fluid reservoir is under the The brake fluid reservoir is under the hood right in front of the steering hood right in front of the steering wheel. Most cars today have a wheel. Most cars today have a transparent reservoir so that you can transparent reservoir so that you can see the level without opening the cover. see the level without opening the cover. The brake fluid level will drop slightly as The brake fluid level will drop slightly as the brake pads wear out. This is a the brake pads wear out. This is a normal condition and you shouldn't normal condition and you shouldn't worry about it. If the level drops worry about it. If the level drops noticeably over a short period of time or noticeably over a short period of time or goes down to about two thirds full, have goes down to about two thirds full, have your brakes checked as soon as your brakes checked as soon as possible. possible.

• Power steering fluidPower steering fluidThe power steering fluid reservoir usually The power steering fluid reservoir usually has a small dipstick attached to the cap. has a small dipstick attached to the cap. Remove the cap and check the fluid level. Remove the cap and check the fluid level. The level should not change more than the The level should not change more than the normal range on the stick. If you have to normal range on the stick. If you have to add fluid more than once or twice a year, add fluid more than once or twice a year, then have the system checked for leaks. then have the system checked for leaks. These systems are easily damaged if you These systems are easily damaged if you drive while the fluid is very low. Another drive while the fluid is very low. Another warning of low power steering fluid is a warning of low power steering fluid is a buzzing noise when you turn the steering buzzing noise when you turn the steering wheel at slow speeds.wheel at slow speeds.

• Coolant (Antifreeze) levelCoolant (Antifreeze) levelNever open the radiator of a car that Never open the radiator of a car that has just been running.has just been running. The cooling The cooling system of a car is under high pressure system of a car is under high pressure with fluid that is usually hotter than boiling with fluid that is usually hotter than boiling water. Look for the cooling system reserve water. Look for the cooling system reserve tank, somewhere near the radiator. It is tank, somewhere near the radiator. It is usually translucent white so you can see usually translucent white so you can see the fluid level without opening it. (Do not the fluid level without opening it. (Do not confuse it with the windshield washer confuse it with the windshield washer tank). The reserve tank will have two tank). The reserve tank will have two marks on the side of it. "FULL HOT" and marks on the side of it. "FULL HOT" and "FULL COLD." If the level frequently goes "FULL COLD." If the level frequently goes below "full cold" after adding fluid, you below "full cold" after adding fluid, you probably have a leak which should be probably have a leak which should be checked as soon as possible. checked as soon as possible.

• BatteryBatteryMost batteries today are "maintenance Most batteries today are "maintenance free" which simply means that you can't free" which simply means that you can't check the water level. This doesn't mean check the water level. This doesn't mean however, that there is nothing to check. however, that there is nothing to check. The main things to check are the top of The main things to check are the top of the battery which should be clean and dry, the battery which should be clean and dry, and the terminal connections which should and the terminal connections which should be clean and tight. If the top of the battery be clean and tight. If the top of the battery continuously becomes damp or corroded continuously becomes damp or corroded soon after cleaning, then have the soon after cleaning, then have the charging system and battery checked by charging system and battery checked by your mechanic. your mechanic.

• Windshield washer solventWindshield washer solventWindshield washer solvent is readily Windshield washer solvent is readily available by the gallon in auto supply available by the gallon in auto supply stores as well as supermarkets and it stores as well as supermarkets and it is cheap. It is fine to use with or is cheap. It is fine to use with or without adding water but will clean without adding water but will clean better undiluted. Never dilute it better undiluted. Never dilute it during winter months to insure that it during winter months to insure that it retains its antifreeze protection. retains its antifreeze protection.

• Belts & HosesBelts & HosesIn most cases your mechanic can In most cases your mechanic can check your belts and hoses when you check your belts and hoses when you bring in the car for an oil change. bring in the car for an oil change. However, if you get your oil changed However, if you get your oil changed by some quick lube type centers, by some quick lube type centers, belts and hoses may not be on their belts and hoses may not be on their list of items to check in which case list of items to check in which case you're on your own. These checks you're on your own. These checks are best done while the car is cold. are best done while the car is cold.

Oil ChangeOil Change• Regular oil changes are the best way to Regular oil changes are the best way to

ensure longer engine life. If you frequently ensure longer engine life. If you frequently take short trips where the car doesn't always take short trips where the car doesn't always completely warm up, then oil changes are completely warm up, then oil changes are even more important because acid and even more important because acid and moisture buildup does not have a chance to moisture buildup does not have a chance to burn off.  Some new engines normally run very burn off.  Some new engines normally run very hot and are very hard on oil. Even missing a hot and are very hard on oil. Even missing a single oil change on these cars can cause an single oil change on these cars can cause an engine to develop sludge which can cause engine to develop sludge which can cause engine damage in a car with as little as 15,000 engine damage in a car with as little as 15,000 miles on the odometer miles on the odometer