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Ch 11 Mod Auto Tech
Modern Automotive Technology Ch11 Engine Fundamentals Vocab
| Question | Answer |
|---|---|
| Engine | The source of power for a vehicle |
| Fuel | The energy source, usually gasoline or diesel |
| Combustion chamber | Hollow area between the top of the piston and the bottom of the cylinder head |
| Expansion | Enlargement |
| Top dead center (TDC) | When the piston is at the highest point in the cylinder |
| Bottom dead center (BDC) | When the piston is at the lowest point in the cylinder |
| Piston stroke | The distance the piston slides up or down from TDC to BDC. Takes one half turn of the crankshaft. |
| Four-stroke cycle | requires four piston strokes to complete one cycle |
| Intake stroke | In a gasoline engine, draws fuel and air into the engine. Intake valve is open, exhaust valve is closed. Piston slides down to form a vacuum in the cylinder |
| Compression stroke | Squeezes the air fuel mixture to prepare it for combustion (burning). Fuel is more combustible when pressurized. Both valves are closed. |
| Power stroke | Burns the air-fuel mixture, pushes the piston down with tremendous force spinning the crankshaft. Only stroke that doesn’t consume energy. In gasoline engines a spark plug fires which ignites the air-fuel mixture. Both valves closed. |
| Exhaust stroke | Removes burned gases from engine, readies engine for a fresh charge of air and fuel. Piston moves up, intake valve is closed exhaust valve is open. |
| Engine bottom end | refers to the block, crankshaft, connecting rods, pistons and related components. Also called a short block. |
| Engine Block | AKA cylinder block, forms the main body of the engine. Other parts bolt to or fit inside the block. |
| Cylinders | AKA cylinder bores are large round holes machined through the block from top to bottom. Pistons are slightly smaller in diameter than the cylinder to allow proper fit. |
| Deck | AKA deck surface is the top of the block surrounding the cylinders which is machined perfectly flat. Cylinder head bolts here. Deck contains oil and coolant passages to allow lubrication and cooling of cylinder head parts. |
| Water jackets | coolant passages throughout the block that allows a solution of water and antifreeze to cool the cylinders. |
| Core plugs | AKA freeze plugs are round metal plugs on the outside of the block. Seal holes left in the block after casting (manufacture) to prevent coolant leakage out of the water jackets. |
| Main bearing bores | Holes machined in the bottom of the block to hold the crankshaft. Removable bearing inserts fit into these bores. |
| Main caps | bolt to the bottom of the block and hold the crankshaft and main bearing inserts in place. Normally secured by two or four large bolts. |
| Crankcase | Lowest portion of the block. Crankshaft rotates inside the crankcase. |
| Crankshaft | Harnesses the power from the downward force of the pistons. Changes the up/down motion of the piston into a rotating motion. Sits in the bottom of the engine block. |
| Crankshaft main journals | surfaces that are precisely machined and polished which fit into the block’s main bearings. |
| Crankshaft rod journals | Machined and polished surfaces off-set from the main journals. Connecting rods bolt to the rod journals. When the engine is running the rod journals circle around the centerline of the crankshaft. |
| Counterweights | formed on the crankshaft to prevent vibrations. Weights counteract the weight of the connecting rods, pistons, rings and rod journal offset. |
| Crankshaft snout | Sticks through the front of the block. Provides a mounting point for the camshaft drive mechanism, front damper and fan belt pulleys. |
| Crankshaft flange | Holds the flywheel. Center of the flange has a pilot hole or bushing for the transmission torque converter or input shaft. |
| Engine main bearings | removable inserts that fit between the block main bore and the crankshaft main journals. Half of each insert fits into the block; the other half fits into the block main caps. |
| Main thrust bearing | limits how far the crankshaft can slide forward of rearward in the block. |
| Crankshaft oil seals | keep oil from leaking out the front and rear of the engine around the front and rear of the crankshaft. |
| Rear main oil seal | fits around the rear of the crankshaft to prevent oil leakage. Can be a one or two piece seal. Seal lip rides on a machined, polished surface on the crankshaft. |
| Flywheel | Large wheel mounted on the rear of the crankshaft. Serves several functions. |
| Connecting Rod | fastens the piston to the crankshaft. Transfers piston movement to crankshaft rod journals. |
| Connecting rod bearings | ride on the crankshaft rod journals. Fit between the connecting rods and the crankshaft. Also removable. |
| Piston | transfers the pressure of combustion to the connecting rod and crankshaft. Also holds piston rings and piston pin while operating in the cylinder. |
| Piston pin | AKA wrist pin allows the piston to swing on the connecting rod. Fits through the hole in the piston and the connecting rod small end. |
| Piston clearance | amount of space between the sides of the piston and the cylinder wall. Clearance allows a lubricating film of oil to form between the piston and the cylinder and allows for expansion when piston heats up. |
| Piston rings | seal the clearance between the outside of the piston and the cylinder wall. Keep combustion pressure from entering the crankcase and oil from entering the combustion chambers. Most pistons take three rings |
| Compression rings | Prevent blowby; combustion pressure leaking into the crankcase. On compression stroke, pressure is trapped between the cylinder & the piston grooves by these rings; pushes the rings down in their grooves & out against the cylinder wall forming a seal. |
| Oil rings | prevent engine oil from entering the combustion chamber. Scrape excess oil off the cylinder wall. If too much oil is in combustion chamber vehicle will emit blue smoke. |
| Engine top end | refers to the cylinder heads, valves, camshaft and other related components. These parts work together to control fuel, exhaust and air flows. |
| Cylinder head | bolts to the deck of the cylinder block, covers and encloses the top of the cylinder. |
| Combustion chambers | small pockets formed in the cylinder heads directly over the pistons. Where combustion occurs. Spark plugs, in gasoline engines, protrude through holes and into the combustion chambers. |
| Intake ports | route air(diesel engine) or air and fuel(gasoline engine) into the combustion chamber |
| Exhaust port | routes burned gases out of the engine |
| Valve guides | small holes machined through the cylinder head for the valves. |
| Valve seats | round machined surfaces in the combustion chamber port openings. When a valve is closed it seals against the valve seat. |
| Engine valve train | consist of the valves and the parts that operate them. Including the camshaft, lifters, push rods, rocker arms, valves and valve spring assemblies. |
| Camshaft | Has lobes that open each valve. Can be located in the engine block or cylinder head. |
| Valve Lifters | AKA tappet usually rides on the cam lobes and transfers motion to the rest of the valve train. Can be located in engine block or cylinder head. Fit into lifter bores which are machined into the block or head. |
| Push rods | transfer motion between lifters and the rocker arms. Required when camshaft is located in the cylinder block. Hollow metal tube with a ball or socket formed on each end, one end fits into the lifter, the other against the rocker arm. |
| Rocker arms | used to transfer motion of the valves. Mount on top of the cylinder head. Pivot mechanism allows them to rock back and forth as they open and close the valves. |
| Intake valve | The larger valve. Controls the flow of the fuel mixture (gasoline engine) or air (diesel) into the combustion chamber. Fits into the port leading from the intake manifold. |
| Exhaust valve | controls the flow of exhaust gases out of the cylinder. Smaller than the intake valve. Fits into the port leading to the exhaust manifold. |
| Valve seals | prevent oil from entering the combustion chambers through the valve guides. Fit over the valve stems. |
| Valve spring assembly | used to close the valve. Consists of a valve spring, a retainer and two keepers. |
| Keepers | fit into the grooves cut in the valve and lock the retainer and spring on the valve. |
| Intake manifold | bolts to the side of the cylinder head/heads. Contains passages going to each cylinder head port to route air and/or fuel. Either fuel injectors and throttle body (late-model engines) or carburetor (older engines) mount on the intake manifold. |
| Exhaust manifold | bolts to the cylinder head over the exhaust ports to carry burned gases into the exhaust system. Made of either heavy cast iron or lightweight aluminum or stainless steel tubing. |
| Valve cover | AKA rocker cover is a thin metal or plastic cover over the top of the cylinder head to keep valve train oil spray from leaking onto the engine. |
| Engine front end | operates the engine camshaft and sometimes the oil pump, distributor, engine sensors and diesel injection pump. Consists of a drive mechanism for the camshaft and other devices, a front cover, an oil seal and a crankshaft damper. |
| Camshaft drive | Needed to turn the camshaft at one-half engine speed. A belt, sprockets, gears or chain and sprockets can be used to turn the camshaft. AKA the timing belt, timing gears or timing chain because they time the camshaft with the crankshaft. |
| Front Cover | Bolts over the crankshaft snout,holds an oil seal to seal front of the crankshaft. Called a timing cover when used with a gear or chain type camshaft drive. In belt drive, cover doesn’t enclose cam drive or timing mechanism; requires a second cover |
| Crank damper | AKA harmonic balancer or vibration damper. Heavy wheel on the crankshaft snout. Mounted in rubber and helps prevent crankshaft vibration and damage. |
| Flywheel | Connects the engine crankshaft to the transmission/transaxle. Either the clutch or the automatic transmission torque converter bolts to the flywheel. |
| Flywheel | In a manual transmission vehicle, flywheel is very heavy and helps smooth engine operation. |
| Flywheel | Flywheel generally contains a large ring gear which is used to start the engine. A small gear on the starter motor engages the flywheel ring gear and turns the flywheel. |
Created by:
atulloch
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