2. 11
Chapter
Engine Fundamentals

3. Objectives After studying this chapter, you will be able to:
Identify the major parts of a typical automotive engine.
Describe the four-stroke cycle.
Define common engine terms.
Explain the basic function of the major parts of an automotive engine.

4. Objectives
Cite and demonstrate safe working practices related to engines.
Correctly answer ASE certification test questions that require knowledge of the basic operation of piston engines.

5. Engine Operation Engine Fuel Combustion chamber
Source of power for vehicle
Fuel
Energy source
Combustion chamber
Hollow area between top of piston and bottom of cylinder head where fuel is burned

6. Engine Operation (Cont.)
Combustion produces heat
Heat causes expansion of gases in engine
Expansion causes pressure
Piston, connecting rod, and crankshaft
Convert pressure to motion
Motion drives gears, chains, sprockets, and belts
Move car, operate systems

7. Piston Travel Distance piston moves up or down Top dead center (TDC)
Crankshaft limitation
Top dead center (TDC)
Bottom dead center (BDC)
Piston stroke
TDC to BDC distance

8. Piston Travel (Cont.)
(Ford)

9. Four-Stroke Cycle

10. Four-Stroke Cycle (Cont.)

11. Four-Stroke Cycle (Cont.)

12. Four-Stroke Cycle (Cont.)

13. Engine Bottom End Block Crankshaft Connecting rods Pistons
Related components

14. Engine Block Also known as cylinder block Cylinders Pistons
Main body of engine
Cylinders
Large round holes machined through block
Pistons
Fit into cylinders
Deck or deck surface
Top of block surrounding cylinders
Cylinder head bolts to deck

15. Engine Block (Cont.) Water jackets Core plugs or freeze plugs
Coolant passages through block
Core plugs or freeze plugs
Round metal plugs
Seal holes left in block from casting
Prevent coolant leakage
Main bearing bores
Holes machined in bottom of block to hold crankshaft
Contain removable bearing inserts

16. Engine Block (Cont.) Main caps Engine bedplate Crankcase
Bolt to bottom of block
Hold crankshaft and main bearing inserts in place
Engine bedplate
Large metal girdle that replaces all main bearing caps
Crankcase
Lowest portion of block
Crankshaft rotates inside

17. Crankshaft Harnesses force produced by pistons
Changes up-and-down motion into rotating motion
Fits into bottom of engine block

18. Crankshaft (Cont.) Main journals Rod journals Precisely polished
Fit into main bearings
Rod journals
Offset from main journals
Connecting rods bolt to journals
Revolve around centerline of crankshaft

19. Crankshaft (Cont.) Counterweights Snout
Counteract weight of connecting rods, pistons, rings, and rod journal offset
Prevent vibration
Snout
Sticks out of end of block
Provides mount for camshaft drive mechanism, front damper, and fan belt pulleys

20. Crankshaft (Cont.) Flange Rod journals Flywheel bolts to flange
Center of flange has pilot hole or bushing
Transmission torque converter or input shaft
Rod journals
Arranged so always at least one cylinder on power stroke
Force always being transmitted to crankshaft

21. Engine Main Bearings
Fit between block main bores and crankshaft main journals
Consist of two removable inserts
Upper main bearing
Fits into cylinder block
Lower main bearing
Fits into main caps or bedplate

22. Engine Main Bearings (Cont.)
Oil holes and grooves
Allow oil to flow through block, main bearings, and crankshaft
Main thrust bearing
Limits distance crankshaft can slide in block
Flanges limit end play

23. Engine Main Bearings (Cont.)
Main bearing clearance
Space between crankshaft main journal and main bearing insert
Allows oil to enter and journal to rotate without rubbing

24. Crankshaft Oil Seals
Keep oil from leaking from front and rear of engine
Rear main oil seal
Fits around rear of crankshaft
Front seal
Prevents leakage around crankshaft snout

25. Flywheel Large metal disc mounted on rear of crankshaft
Connects crankshaft to transmission or transaxle
Very heavy
Helps smooth engine operation
Contains large ring gear used to start the engine

26. Connecting Rod Fastens piston to crankshaft Connecting rod bearings
Transfers piston motion
Connecting rod bearings
Ride on crankshaft rod journals
Fit between connecting rods and crankshaft

27. Piston
Transfers pressure of combustion to connecting rod and crankshaft
Piston head
Top of piston
Piston ring grooves
Slots cut in piston for piston rings
Piston oil holes
Allow oil to flow through piston and onto cylinder wall

28. Piston (Cont.) Piston ring lands Piston skirt Piston boss
Areas above and between ring grooves
Piston skirt
Side of piston below last ring
Piston boss
Reinforced area around piston pin hole
Piston pin hole
Hole in piston boss for piston pin

29. Piston Pin Also called wrist pin
Allows piston to swing on connecting rod

30. Piston Rings Seal space between piston and cylinder wall
Most pistons use three rings
Two upper compression rings
One lower oil ring

31. Piston Rings (Cont.) Compression rings Oil rings Ring gap
Prevent combustion pressure from leaking into engine crankcase (blowby)
Oil rings
Prevent engine oil from entering combustion chamber
Ring gap
Split or space between ends of piston ring

32. Engine Top End
Controls airflow and sometimes fuel into engine cylinders
Controls flow of exhaust out of the engine
(Chrysler)

33. Cylinder Head
Bolts to deck of cylinder block and encloses top of cylinders
Intake and exhaust ports
Cast into cylinder head
Intake ports route air
Exhaust ports route burned gases out of engine

34. Cylinder Head (Cont.) Valve guides Valve seats
Small holes machined through cylinder head for valves
Valve seats
Round machined surfaces in combustion chamber port openings

35. Valve Train Valves and operational parts Camshaft Lifters Push rods
Rocker arms
Valves
Valve seals
Valve spring assemblies

36. Valve Train (Cont.)
(Ford)

37. Valve Train (Cont.) Camshaft Located in engine block or cylinder head
Journals
Cam lobes
Drive gear
Thrust plate
Eccentric

38. Valve Train (Cont.) Valve lifter or tappet Push rods Rocker arms
Rides on cam lobes and transfers motion to valve train
Push rods
Transfer motion between lifters and rocker arms
Rocker arms
Transfers motion to valves
Rock back and forth opening and closing valves

39. Valve Train (Cont.) Valves Open and close ports in cylinder head
Intake valves
Control flow of fuel mixture
Larger than exhaust valves
Exhaust valves
Control flow of exhaust gases out of cylinder

40. Valve Parts
Valve head
Margin
Face
Stem
Keeper grooves
Valve stem tip

41. Valve Seals
Prevent oil from entering combustion chamber through valve guides
(American Hammered Piston Rings)

42. Valve Spring Assembly Used to close valves Valve spring Retainer
Two keepers
Shield

43. Intake Manifold Bolts to side of cylinder head(s)
Contains runners or passages going to each cylinder head intake port
Air and fuel route through runners
With fuel injectors, only air passes through runners
Injectors extend directly into combustion chamber

44. Exhaust Manifold Fastens over exhaust ports
Carries burned gases into exhaust system
Heavy cast iron
Aluminum
Stainless steel tubing

45. Valve Cover Also called rocker cover
Thin metal or plastic lid over top of cylinder head
Keeps valve train oil spray from leaking out of engine

46. Intake and Exhaust Manifolds

47. Engine Front End All parts attached to front of engine Camshaft drive
Front cover
Oil seal
Crank damper

48. Engine Front End (Cont.)
Additional attached parts
Oil pump
Water pump
Chain or belt tensioners
Auxiliary drives or sprockets
Engine sensors

49. Engine Front End Components
(Chrysler)

50. Camshaft Drive Needed to turn camshaft at one-half engine speed
Timing belt
Timing gears
Timing chain
Times camshaft with crankshaft

51. Front Cover Bolts over crankshaft snout
Holds oil seal that seals front of crankshaft
Also called timing cover
(Ford)

52. Crank Damper Heavy wheel on crankshaft snout Mounted in rubber
Helps prevent vibration and damage
Harmonic balancer
Vibration damper