OBJECTIVES

2. OBJECTIVES After studying Chapter 14, the reader will be able to: • Prepare for Engine Repair (A1) ASE certification test content area “D” (Lubrication and Cooling Systems Diagnosis and Repair). • Explain engine oil ratings. • Describe how an oil pump and engine lubrication work. • Discuss how and when to change the oil and filter. • Explain how to inspect an oil pump for wear.

3. LUBRICATION PURPOSE AND FUNDAMENTALS • Engine oil is the lifeblood of any engine. The purposes of engine oil include the following: • Lubricating all moving parts to prevent wear. • Helping to cool the engine. • Helping to seal piston rings. • Cleaning, and holding dirt in suspension in the oil until it can be drained from the engine. • Neutralizing acids that are formed as the result of the combustion process. • Reducing friction. • Preventing rust and corrosion.

4. LUBRICATION PRINCIPLES • Lubrication between two moving surfaces results from an oil film that separates the surfaces and supports the load. FIGURE 14-1 Oil molecules cling to metal surfaces but easily slide against each other.

5. LUBRICATION PRINCIPLES • If oil were put on a flat surface and a heavy block were pushed across the surface, the block would slide more easily than if it were pushed across a dry surface. • The reason for this is that a wedge-shaped oil film is built up between the moving block and the surface. FIGURE 14-2 Wedge-shaped oil film developed below a moving block.

6. LUBRICATION PRINCIPLES • This wedging action is called hydrodynamic lubrication and the pressure depends on the force applied to how fast the speed between the objects and the thickness of the oil. • Thickness of oil is called the viscosity and is defined as the ability of the oil to resist flow.

7. LUBRICATION PRINCIPLES • Hydrodynamic lubrication occurs when a wedge-shaped film of lubricating oil develops between two surfaces that have relative motion between them. FIGURE 14-3 Wedge-shaped oil film curved around a bearing journal.

8. LUBRICATION PRINCIPLES FIGURE 14-4 Typical V-8 engine lubrication system. Oil is stored in the oil pan (sump), drawn into the oil pump, and moves through the oil filter and on through the oil passages (oil galleries).

9. PROPERTIES OF ENGINE OIL • The most important engine oil property is its thickness or viscosity. • As oil cools, it thickens. As oil heats, it gets thinner.

10. SAE RATING • Engine oils are sold with an SAE (Society of Automotive Engineers) grade number, which indicates the viscosity range into which the oil fits. • Most vehicle manufacturers recommend the following multiviscosity engine oils: • SAE 5W-30 • SAE 10W-30

11. SAE RATING • Thinner oil • Improved cold-engine starting • Improved fuel economy • Thicker oil • Improved protection at higher temperatures • Reduced fuel economy

12. API RATING • The American Petroleum Institute (API), working with the engine manufacturers and oil companies, has established an engine oil performance classification. FIGURE 14-5 API doughnut for a SAE 5W-30, SM engine oil. When compared to a reference oil, the “energy conserving” designation indicates a 1.1% better fuel economy for SAE 10W-30 oils and 0.5% better fuel economy for SAE 5W-30 oils.

13. API RATINGGasoline and Diesel Engine Rating • In gasoline engine ratings, the letter S means service, but it can be remembered as being for use in spark ignition engines. • Diesel classifications begin with the letter C, which stands for commercial, but can also be remembered as being for use in compression ignition or diesel engines.

14. ILSAC OIL RATING • The International Lubricant Standardization and Approval Committee (ILSAC) developed an oil rating that consolidates the SAE viscosity rating and the API quality rating. • If an engine oil meets the standards, a “starburst” symbol is displayed on the front of the oil container. FIGURE 14-6 The International Lubricant Standardization and Approval Committee (ILSAC) starburst symbol. If this symbol is on the front of the container of oil, then it is acceptable for use in almost any gasoline engine.

15. EUROPEAN OIL RATINGS • The Association des Constructeurs European d’Automobiles (ACEA) represents most of the Western European automobile and heavy-duty truck market. • The organization uses different engines for testing than those used by API and SAE, and the requirements necessary to meet the ACEA standards are different yet generally correspond with most API ratings. • ACEA standards tend to specify a minimum viscosity rating and certain volatility requirements not specified by API.

16. JAPANESE OIL RATINGS • The Japanese Automobile Standards Organization (JASO) also publishes oil standards. • The JASO tests use small Japanese engines, and their ratings require more stringent valve train wear standards than other countries’ oil ratings.

17. ENGINE OIL ADDITIVES • Additives are used in engine oils for three different reasons: • To replace some properties removed during refining. • To reinforce some of the oil’s natural properties. • To provide the oil with new properties it did not originally have.

18. ENGINE OIL ADDITIVES • Additives are usually classified according to the property they add to the oil. • Antioxidants • Corrosion preventives • Detergents and dispersants • Extreme pressure • Viscosity index (VI) improvers change as the oil temperature changes. • Pour point depressants FIGURE 14-7 VI improver is a polymer and feels like finely ground foam rubber. When dissolved in the oil, it expands when hot to keep the oil from thinning.

19. OIL BRAND COMPATIBILITY • According to SAE Standard J-357, all engine oils must be compatible (miscible) with all other brands of engine oil. • Therefore, any brand of engine oil can be used as long as it meets the viscosity and API standards recommended by the vehicle manufacturer.

20. SYNTHETIC OIL • The term synthetic means that it is a manufactured product and not refined from a naturally occurring substance, as engine oil (petroleum base) is refined from crude oil. • According to the American Petroleum Institute, engine oil is classified into five groups.

21. SYNTHETIC OIL FIGURE 14-8 Container of oil with the ILSAC starburst symbol on the front. The tri-synthetic label indicates that it contains Group IV (POA) as well as Group V (diesters) to swell seals, and some Group III (hydrocracked oil).

22. SYNTHETIC OIL FIGURE 14-9 Both oils have been cooled to 20°F (29°C). Notice that the synthetic oil on the left flows more freely than the mineral oil on the right even though they are both SAE 5W-30.

23. OIL TEMPERATURE • Excessive temperatures, either too low or too high, are harmful to any engine. • If the oil is too cold, it could be too thick to flow through and lubricate all engine parts. • If the oil is too hot, it could become too thin to provide the film strength necessary to prevent metal-to-metal contact and wear. • Estimated oil temperature can be determined with the following formula: • Outside air temperature + 120°F

24. OIL CHANGE INTERVALS • All vehicle and engine manufacturers recommend a maximum oil change interval. • The recommended intervals are almost always expressed in terms of mileage or elapsed time (or hours of operation), whichever milestone is reached first. • Most technicians and automotive experts recommend changing the oil every 2,000 to 3,000 miles or every two to three months, whichever occurs first.

25. OIL CHANGE PROCEDURE • Position a drain pan under the drain plug; then remove the plug with care to avoid contact with hot oil. • Allow the oil to drain freely so that the contaminants come out with the oil. • When the oil stops running and starts to drip, reinstall and tighten the drain plug.

26. OIL CHANGE PROCEDURE • Replace the oil filter if that is to be done during this oil change. • Refill the engine with the proper type, grade, and quantity of oil. • Restart the engine and allow the engine to idle until it develops oil pressure; then check the engine for leaks, especially at the oil filter.

27. THE PICK TRICK FIGURE 14-10 (a) A pick is pushed through the top of an oil filter that is positioned vertically. (b) When the pick is removed, a small hole allows air to get into the top of the filter which then allows the oil to drain out of the filter and back into the engine.

28. BYPASS FLOW OIL FILTER FIGURE 14-11 This early Chevrolet V-8 has what was an optional oil filter, which is connected to an oil gallery and return oil flows into the oil pan.

29. OIL FILTERS • The filter is made from either closely packed cloth fibers or a porous paper. • Large particles are trapped by the filter. • Microscopic particles will flow through the filter pores. • These particles are so small that they can flow through the bearing oil film and not touch the surfaces, so they do no damage.

30. OIL FILTERS • Many oil filters are equipped with an antidrainback valve that prevents oil from draining out of the filter when the engine is shut off. FIGURE 14-12 A rubber diaphragm acts as an antidrainback valve to keep the oil in the filter when the engine is stopped and the oil pressure drops to zero.

31. OIL FILTERS • Either the engine or the filter is provided with a bypass valve that will allow the oil to go around the filter element. FIGURE 14-13 A cutaway of an oil filter showing the location of a typical bypass valve. When the oil filter becomes clogged, the bypass valve opens, allowing the engine to receive oil even though it is not filtered.

32. OIL FILTERS • Most engine manufacturers recommend filter changes at every other oil change period. FIGURE 14-14 A typical oil filter crusher. The hydraulic ram forces out most of the oil from the filter. The oil is trapped underneath the crusher and is recycled.

33. CHANGING OIL IN A TURBOCHARGED ENGINE • To prime most late-model turbocharged engines, simply depress the accelerator to the floor and crank for 15 seconds. • To start the engine, simply return the accelerator pedal to the idle position and crank the engine.

34. OIL PUMPS • All production automobile engines have a full-pressure oil system. • The pressure is maintained by an oil pump. • The oil is forced into the lubrication system under pressure. • In most engines that use a distributor, the distributor drive gear meshes with a gear on the camshaft.

35. OIL PUMPS FIGURE 14-15 An oil pump driven by the camshaft.

36. OIL PUMPS FIGURE 14-16 A typical oil pump mounted in the front cover of the engine that is driven by the crankshaft. FIGURE 14-17 Geroter-type oil pump driven by the crankshaft.

37. OIL PUMPS • Most automotive engines use one of two types of oil pumps: gear or rotor. • All oil pumps are called positive displacement pumps, and each rotation of the pump delivers the same volume of oil; thus, everything that enters must exit.

38. OIL PUMPS FIGURE 14-18 In a gear-type oil pump, the oil flows through the pump around the outside of each gear. This is an example of a positive displacement pump, wherein everything entering the pump must leave the pump.

39. OIL PRESSURE REGULATION • In engines with a full-pressure lubricating system, maximum pressure is limited with a pressure relief valve. • The relief valve (sometimes called the pressure regulating valve) is located at the outlet of the pump. FIGURE 14-19 Oil pressure relief valves are spring loaded. The stronger the spring tension, the higher the oil pressure.

40. OIL PRESSURE REGULATION FIGURE 14-20 A typical engine design that uses both pressure and splash lubrication. Oil travels under pressure through the galleries (passages) to reach the top of the engine. Other parts are lubricated as the oil flows back down into the oil pan or is splashed onto parts.

41. OIL PRESSURE REGULATION FIGURE 14-21 An intermediate shaft drives the oil pump on this overhead camshaft engine. Note the main gallery and other drilled passages in the block and cylinder head.

42. FACTORS AFFECTING OIL PRESSURE • Oil pressure can only be produced when the oil pump has a capacity larger than all the “leaks” in the engine. • If the leaks are greater than the pump capacity, engine oil pressure is low.

43. OIL PUMP CHECKS • The cover is removed to check the condition of the oil pump. • The gears and housing are examined for scoring. • If the gears and housing are heavily scored, the entire pump should be replaced. If they are lightly scored, the clearances in the pump should be measured.

44. OIL PUMP CHECKS FIGURE 14-22 (a) A visual inspection indicated that this pump cover was worn. (b) An embedded particle of something was found on one of the gears, making this pump worthless except for scrap metal.

45. OIL PUMP CHECKS FIGURE 14-23 (a) The oil pump is the only part in an engine that gets unfiltered engine oil. The oil is drawn up from the bottom of the oil pan and is pressurized before flowing to the oil filter. (b) If debris gets into an oil pump, the drive or distributor shaft can twist and/or break. When this occurs the engine will lose all oil pressure.

46. OIL PUMP CHECKS FIGURE 14-24 Gear-type oil pump being checked for tooth clearance in the housing.

47. OIL PUMP CHECKS FIGURE 14-25 Measuring the gear-to-cover clearance of an oil pump.

48. OIL PUMP CHECKS • Typical oil pump clearances include the following: • End plate clearance: 0.0015 inch (0.04 millimeter) • Side (rotor) clearance: 0.012 inch (0.30 millimeter) • Rotor tip clearance: 0.010 inch (0.25 millimeter) • Gear end play clearance: 0.004 inch (0.10 millimeter)

49. OIL PASSAGES IN THE BLOCK • From the filter, oil goes through a drilled hole that intersects with a drilled main oil gallery or longitudinal header.

50. OIL PASSAGES IN THE BLOCK FIGURE 14-26 Oil flow through an engine starts at the oil pump pickup and eventually ends up with the oil dropping back into the oil pan.