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 Manifold 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 Anaerobic 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.