ENGINES AUTO 1-2

1
ENGINES AUTO 1-2
Pasco High Auto Shop
2
1. Engine Block
3
1. Engine Block

• Metal foundation
• Supports crankshaft and usually camshaft made of
  cast iron or aluminum, aluminum parts that wear
  will have metal inserts that are pressed or cast
  into the block.
• Cylinder - round hole formed in block bored and
  honed to a fine finish, acts as a guide for
  piston and a container for the fuel charge

4
2. Cylinder Sleeves

• Round pipe like liners

5
2. Cylinder Sleeves

• Removable type or cast into block, wet and dry
  sleeves,
• DRY pressed in block supported and surrounded,
  its full length - most common gas engine.
• WET pressed in block supported only at top and
  bottom - cooling water comes in direct contact -
  heavier construction has sealing rings

6
Securing sleeves

• When cast into block they usually have grooves in
  the outside of sleeves to secure it when pressed
  in it can have flange on top or will be held in
  only by friction of a pressed fit - head will
  keep it from coming up.

7
3. Piston

• Sliding plunger in cylinder creates vacuum on
  intake stroke, compresses mixture on compression
  stroke transmits and contains the pressure of the
  firing stroke, cleans the cylinder of burned
  gases on the exhaust stroke.

8
Piston materials

• aluminum - cast - most common,
• forged- found in hi-performance engines

9
Expansion of Piston

• If the piston is to loose it can cause piston
  slap, piston too loose in cylinder tips from side
  to side

10
Old styles of Piston

• split skirt, skirt closes as piston warms up.
• T slot, same as split skirt but has a T top to
  prevent heat of piston head transferring to skirt
• steel strut, steel cast into aluminum piston
  steel expands less then aluminum and helps reduce
  expansion

11
New style

• cam ground, minimum clearance on thrust sides egg
  shaped
• thrust surface, side of piston that is at right
  angles to crank shaft and piston pin surface side
  that prevents tipping and supports the piston.

12
skirts

• full skirt skirt goes all the way around piston
  not cut away.
• slipper skirt, piston skirt cut away below piston
  pin for counter weights piston lighter reduces
  inertia load on bearings makes engine more
  responsive

13
piston temperature

• head of piston up to and above 600' F bottom of
  skirt about 300'F, head of piston is .030 to .040
  in smaller then skirt to allow for expansion top
  can be of different shapes

14
Piston Shapes

• flat, dome, wedge, irregular - to help in
  exhausting burned gases
• Piston pin boss, section of piston that supports
  piston pin inboard pin boss - most engines, out
  board pin boss - performance and competition
• valve reliefs- small indentations machined into
  the top of the piston.

15
4. Piston rings
3 piece Oil ring
16
4. Piston rings

• ride in grooves in piston head to seal the
  cylinder
• types of rings, compression - prevent pressure
  leakage into the crankcase
• different grooves, bevels, and chamfers causes
  internal stress causing scraper action on
  downward stroke taking any oil down that was
  missed by the oil ring

17
Piston rings

• firing pressure forces top ring down for full
  face contact
• inner groove usually goes up
• outer groove usually goes down
• material, rings made of cast iron, some are
  chrome plated, some are molybdenum coated or a
  grooved filled with moly, some rings are
  stainless steel

18
Oil control rings -

• scrape oil off cylinder wall and send pack to
  crank case all new sets are three piece expander
  and two steel rings some old oil rings are just
  one ring break easy.
• compression and oil control rings can have an
  expander ring to help force out the ring

19
Piston ring gap joints, most common - butt

• lap and bevel have been used
• some engines have a pin in piston ring groove to
  prevent ring from moving
• piston ring gap usually .003-.004 for each inch
  of cylinder diameter

20
Ring Width

• Distance from the top to the bottom of the ring

21
heat dam

• groove in head of piston that prevents or lowers
  the amount of heat transferred to the top ring
• top ring groove insert, metal insert cast into
  aluminum piston with piston groove cut out of
  insert to help prolong the life of the piston

22
5. Piston Pins

• steel pin used to connect piston to connecting
  rod
• case hardened, soft center .004 outside hardened
  highly polished

23
securing piston pins

• 1. full floating pin, snap ring each end pin can
  turn in piston bosses and connecting rod may have
  bronze bushing

24
securing piston pins

• 2. press fit (rod pressed into the connecting
  rod) pin turns in aluminum piston boss.

25
securing piston pins

• 3. pin locked to rod by bolt not very common.

26
6. Connecting Rods

• connect piston to the crankshaft upper end
  oscillates lower or large end rotates lower end
  must be split for installation of bearing and
  installation on crankshaft journal. before
  removing number rod and rod cap on same side with
  a number.

27
6. Connecting Rods

• Steel Rod Aluminum Rod

28
7. Insert Bearings

• removable bearing split in two pieces for easy
  installation and removal

29
7. Insert Bearings

• steel back with soft lining, coating can be of
  babbitt, copper-lead-tin or aluminum coating
• locating tabs help keeps insert bearing from
  turning

30
Insert Bearings

• crush height the .001 to .002 protruding above
  rod cap and rod that when bolted together forms
  the tight fit that prevents the bearing from
  turning.
• An undersize bearing is used on a crankshaft that
  has been machined to a smaller size.

31
BEARING PERFORMANCE

• load strength- must withstand pounding from
  compression and firing stroke
• anti scuffing - if oil pressure is lost lining
  must be soft enough to prevent crankshaft journal
  from being scratched or scuffed
• corrosion - must resist corrosion from vapors and
  acids in crankcase
• conformation - must conform to shape of
  crankshaft journal

32
BEARING PERFORMANCE

• embedability - must allow small particles to
  embed itself into bearing material so journal
  won't be scratched
• temperature - must work equally well both hot
  and cold must transfer heat well
• oil hole or groove for lubrication

33
BEARINGS

• rod bearings, bearings in the connecting rod
• main bearings, bearings that go where the main
  bearing cap hold the crankshaft in place.

34
THRUST BEARINGS

• thrust bearing, has sides on to help prevent end
  play of crankshaft, sometimes use a separate
  piece for the side.

35
8. Crankshaft

• Crankshaft, change reciprocating motion to
  rotary motion
• made of Forged steel (should ring when you hit
  it with a hammer) or cast iron
• counter balances, forged in crank to offset
  weight of crankshaft throw

36
Crankshaft

• crankshaft throw, the part of crankshaft that the
  connecting rod fastens to also refer to as rod
  journal
• crank main journal, by use of main bearing caps
  crankshaft is bolted to block
• crankshaft is drilled so oil can be fed to main
  bearings and rod bearings, crankshafts are ground
  and highly polished

37
9. Harmonic Balancer or Vibration Damper

• Helps absorb torsional vibration of crankshaft
  and smooth out firing pressure of each cylinder,
  2 pieces with rubber plug or lining

38
10. Flywheel

• 1. smooth out engine speed
• 2. mounting surface for clutch
• 3. starter motor engage ring gear to start
  engine
• 4. carry engine through power strokes

39
11. Camshaft

• opens the valves in engine cam lobes open the
  valves one per valve shape of lobe determines how
  long valve stays open and how far it opens also
  gear to drive the distributor and oil pump an
  eccentric may be ground or bolted onto cam to
  drive the fuel pump

40
12. Timing chain, belt and gears

• drive chain or belt that connects the crankshaft
  gear(driving force) to the cam shaft gear (the
  driven force) camshaft turns at 1/2 crank shaft
  speed.
• light duty chain, heavy duty - double roller,
  driven by all gears, crank gear - steel, cam gear
  - steel, aluminum, pressed fiber, plastic, must
  be aligned

41
tensioner for belt or chain
Off of a 96 Olds chain drive
Off a 75 Toyota 2TC chain drive
42
12. Timing chain
43
12. Timing gears
44
13. Valves

• device used to open and close the valve port,
  engines have 2 3 or 4 valves per cylinder
• some valves have a special hard facing on the
  face stellite faced valves

45
Valves

• valve faces are ground at different angles 29-30
  and 44-45 most common. interface angle valve
  face 44 seat 45, exhaust valve may climb out of
  seat
• cooling, heat dissipates through valve seat and
  valve guide some valves (heavy duty truck) are
  sodium filled to help transfer heat.

46
CAUTION

• SODIUM, IF DROPPED INTO WATER WILL BURST INTO
  FLAMES WILL CAUSE SERIOUS BURNS IF IT GETS ON TO
  YOUR SKIN.

47
14. Valve seat

• Part of head or block that valve face comes in
  contact with to seal cylinder. Can be part of
  head or an insert that is pressed in. most now
  are hardened seats valve seat angle 30 and 45

48
15. Valve springs

• closes valve when lifter comes off cam lobes
  some valves use 2 springs per valve, Must measure
  valve spring installed height, coil bind - spring
  can only go together so far.

49
16. Valve spring retainer

• holds spring in place with a valve lock or keeper

50
Valve keepers

• holds valve in place maybe called a stem lock

51
Valve Stem seals

• Valve seals prevent oil from being drawn into the
  engine. Deflector seals usually called Umbrella
  seals and a Positive seal are the most common
  types. GM uses a O-ring on there engines.

52
17. Valve guide

• hole through which valve passes to keep it in
  proper alignment can be cast into head or pressed
  in must have .002 - .003 clearance

53
18. Valve lifter

• mechanical - solid
• lifters are solid or hollow made of cast iron
  bottom that contacts camshafts is hardened
  adjustment is taken care of in rocker arms on
  most engines some lifters are adjustable.

54
Hydraulic Valve lifter

• Hydraulic, self adjusting has zero valve lash
  clearance(No space between parts), use engine oil
  under pressure to operate are quieter then solid
  lifters operation, may use flat check valve or
  ball.

55
Hydraulic Valve lifter

• Roller Lifter - has a small roller that rolls on
  the camshaft.

56
19. Lifter guide

• bore in block that contain lifter has oil passage
  in it to supply oil to lifter

57
20. Rocker Arm

• Transmit cam lobe action to the valve stem, two
  type adjustable and non adjustable can be mounted
  on shaft or a individual stud, overhead
  cam-rocker arm operates on camshaft (eliminates
  the middle man), roller rockers

58
20. Rocker Arm
59
20. Roller Rocker Arm
60
21. Push rod

• Transmits valve train motion from valve lifter to
  rocker arm

61
22. valve port

• passages which allow the air fuel mixture in and
  the burned fuel out

62
23. Crank case or oil pan

• reservoir for oil usually made of stamped steel
  attached to the bottom of block the oil pump is
  usually with in this reservoir

63
The End Scott Salisbury