Automotive Bearings and Sealants

1. Automotive Bearings and Sealants

2. Objectives • Explain purpose of bearings • Identify different types, construction, and uses of automotive bearings • List types of lubricant used in a light vehicle • Explain different types, construction, and uses of gaskets

3. Objectives • Explain types and uses of chemical automotive sealants • Explain different types, construction, and uses of seals

4. Objectives • Explain the purpose of the various gaskets used to seal an engine. • Identify the major gasket types and their uses. • Explain general gasket installation procedures. • Describe the methods used to seal the timing cover and rear main bearing.

5. Bearings and Bushings • Bearings are used when two components move against or with each other • Bearing Loads • Usually computed by weight and movement of load

6. Bearings and Bushings • Bearing Loads • Weight determines size, placement, and type of bearing to be used • Thrust load looks at direction and amount of force against the weight

7. Bearings and Bushings • Bearing Journals and Races • Machined areas on a shaft • Provide a smooth finish to protect bearing • Usually hardened to withstand loads

8. Bearings and Bushings • Races • Serve same purpose as the journal • Normally included with replacement bearing • Assembled as part of bearing or can be loose

10. Bearings and Bushings • Bearing Inserts • Also known as “plain bearings” • Used in engine as rod or main bearings • Fitted into a mounting component • Two pieces are needed to make one complete bearing

12. Bearings and Bushings • Roller Bearings • Support radial loads and small amount of thrust • Typical roller bearing is fairly small and has several rollers trapped in a cage

13. Bearings and Bushings • Roller Bearings • Cage holds bearings in a circle and maintains equal spacing • Straight or tapered • Needle bearings are also roller bearings • May or may not be held in a cage

15. Bearings and Bushings • Ball Bearings • Similar to a roller bearing • Highly machined steel balls versus rollers • Support axial and radial loads well • Sometimes two rows of balls are present to improve load support

16. Bearings and Bushings • Bushings • Thin steel tubing cut to specific lengths • Coated with copper • Does not support axial loads • Limits radial movement of a shaft • Cannot be used in high-thrust or high-radial load areas

18. Inspecting and Repacking a Wheel Bearing • Bearing failure is indicated by a noise from bearing area • Bearing failure causes two types of damage • Spalling • Brinelling

19. Inspecting and Repacking a Wheel Bearing • Dry bearings can weld themselves to the race or the component

20. Inspecting and Repacking a Wheel Bearing • Remove suspected bearing and clean it thoroughly • Dry bearing with compressed air • Do not allow rollers or cage to spin

21. Inspecting and Repacking a Wheel Bearing • Inspect each ball or roller for damage • Inspect case and race for damage • Any sign of damage warrants replacing bearing

22. Inspecting and Repacking a Wheel Bearing • Repacking the Bearing • Each roller or ball must be greased before installation • Several types of repacking tools are available including compressed-air-powered

23. Inspecting and Repacking a Wheel Bearing • Repacking the Bearing • Bearing must be clean and dry before repacking • Ensure grease extends up through bearing when complete

24. Lubricants • Grease is used on roller and ball bearing components • Grease must be matched to component and its usage • Grease can be multipurpose • Always consult service manual

25. Bearing Construction (Friction reducers) • Friction Bearing- Two smooth surfaces sliding against each other • Antifriction bearing- utilizes balls or rollers between moving parts

26. Antifriction bearings

27. Bearing Clearances • Bearings must be tight enough to resist pounding but lose enough for oil to enter • .002” • .05mm

28. Oil Seals • Oil is retained in the engine from • Gaskets- cork or rubber • Sealants-RTV-Room temperature vulcanizing • Oil seals

29. Gasket Classifications • Hard gaskets • Made of steel, copper, or a composite of metal and fiber • Soft gaskets • Made of cork, rubber, or paper • Silicone gasket material • Three different types • Sealants • Usually in liquid form

30. Gaskets

31. Common Engine Gaskets • Head gaskets • Have the most demanding job. • Manifold gaskets • Are intake, exhaust, or combination. • Valve cover gaskets • Must seal between different metals or materials. • Oil pan gaskets • Seal between the block and pan.

32. Engine Gaskets and Seals

33. Gaskets • Retain lubricants or to seal a chamber • Head Gasket • Seals extremely high pressure of the combustion chamber • Most head gaskets are a composite material • Verify correct part for application

35. Gaskets • Intake and Exhaust • Must be designed to work in extreme heat • Must be able to work between two different metals

36. Gaskets • Other Gaskets • Made from cork, synthetic rubber, neoprene, paper, and chemical-based • Use the right gasket for the job at hand

37. Types of Sealants • Aerobic sealants • Cure only when exposed to oxygen (air). • Are commonly used to form gaskets. • Anaerobic sealants • Cure only in the absence of oxygen (air). • Are used for thread sealant.

38. Chemical Sealants • Chemical sealers • Gasket sealer • Room temperature vulcanizing (RTV) sealer • RTV cannot be used in high heat and high pressure applications

39. Chemical Sealants • Cannot be used on fuel system components • RTV color denotes application and temperature ranges

40. Seals • Used between moving components and their housings to retain liquids • Withstand high pressure and high temperatures • Lip seals are most common type • Some have garter spring to hold seal tight to surface

41. Seals • O-rings • Rubber ring fits into a groove on moving or stationary component • Extends beyond groove and pressed against second component

42. Seals • Boots • Used primarily to protect rather than seal • Most common is CV joint boot

43. Oil Seal Designs • Fiber-packing type • Two-piece lip type • One-piece radial type

44. Oil Seal Designs (Cont’d)

45. Sealants

46. Oil Seals

47. Summary • Sealants include gaskets, chemicals, or seals • Bearings must support axial and radial loads • Gaskets used between stationary parts • Seals used between moving parts • O-rings are special purpose seals

48. Summary • Gaskets serve as sealers, spacers, wear indicators, and vibration dampers. • General recommendations for installing gaskets include the following: • Never reuse old ones. • Clean all mating surfaces. • Use sealants properly.

49. Summary (Cont’d) • Head gaskets on today’s bi-metal engines have a demanding job. • General-purpose sealers aid in gasket sealing without upsetting the performance of the gasket. • Oil seals keep oil and other fluids from escaping around a rotating shaft.