Automotive Bearings and
Sealants
Objectives
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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
Objectives
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Explain types and uses of chemical
automotive sealants
Explain different types, construction, and
uses of seals
Objectives
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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.
Bearings and Bushings
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Bearings are used when two components
move against or with each other
Bearing Loads
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Usually computed by weight and movement of
load
Bearings and Bushings
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Bearing Loads
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Weight determines size, placement, and type of
bearing to be used
Thrust load looks at direction and amount of force
against the weight
Bearings and Bushings
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Bearing Journals and Races
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Machined areas on a shaft
Provide a smooth finish to protect bearing
Usually hardened to withstand loads
Bearings and Bushings
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Races
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Serve same purpose as the journal
Normally included with replacement bearing
Assembled as part of bearing or can be loose
Bearings and Bushings
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Bearing Inserts
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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
Bearings and Bushings
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Roller Bearings
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Support radial loads and small amount of thrust
Typical roller bearing is fairly small and has
several rollers trapped in a cage
Bearings and Bushings
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Roller Bearings
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Cage holds bearings in a circle and maintains
equal spacing
Straight or tapered
Needle bearings are also roller bearings
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May or may not be held in a cage
Bearings and Bushings
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Ball Bearings
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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
Bearings and Bushings
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Bushings
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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
Inspecting and Repacking a Wheel
Bearing
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Bearing failure is indicated by a noise from
bearing area
Bearing failure causes two types of
damage
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Spalling
Brinelling
Inspecting and Repacking a Wheel
Bearing
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Dry bearings can weld themselves to the
race or the component
Inspecting and Repacking a Wheel
Bearing
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Remove suspected bearing and clean it
thoroughly
Dry bearing with compressed air
Do not allow rollers or cage to spin
Inspecting and Repacking a Wheel
Bearing
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Inspect each ball or roller for damage
Inspect case and race for damage
Any sign of damage warrants replacing
bearing
Inspecting and Repacking a Wheel
Bearing
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Repacking the Bearing
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Each roller or ball must be greased before
installation
Several types of repacking tools are available
including compressed-air-powered
Inspecting and Repacking a Wheel
Bearing
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Repacking the Bearing
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Bearing must be clean and dry before
repacking
Ensure grease extends up through bearing
when complete
Lubricants
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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
Bearing Construction (Friction
reducers)
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Friction Bearing- Two smooth surfaces
sliding against each other
Antifriction bearing- utilizes balls or rollers
between moving parts
Antifriction bearings
Bearing Clearances
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Bearings must be tight enough to resist
pounding but lose enough for oil to enter
.002”
.05mm
Oil Seals
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Oil is retained in the engine from
Gaskets- cork or rubber
Sealants-RTV-Room temperature vulcanizing
Oil seals
Gasket Classifications
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Hard gaskets
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Soft gaskets
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Made of cork, rubber, or paper
Silicone gasket material
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Made of steel, copper, or a composite of metal and fiber
Three different types
Sealants
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Usually in liquid form
Gaskets
Common Engine Gaskets
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Head gaskets
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Manifold gaskets
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Are intake, exhaust, or combination.
Valve cover gaskets
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Have the most demanding job.
Must seal between different metals or materials.
Oil pan gaskets
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Seal between the block and pan.
Engine Gaskets and Seals
Gaskets
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Retain lubricants or to seal a chamber
Head Gasket
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Seals extremely high pressure of the combustion
chamber
Most head gaskets are a composite material
Verify correct part for application
Gaskets
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Intake and Exhaust
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Must be designed to work in extreme heat
Must be able to work between two different
metals
Gaskets
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Other Gaskets
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Made from cork, synthetic rubber, neoprene,
paper, and chemical-based
Use the right gasket for the job at hand
Types of Sealants
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Aerobic sealants
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Cure only when exposed to oxygen (air).
Are commonly used to form gaskets.
Anaerobic sealants
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Cure only in the absence of oxygen (air).
Are used for thread sealant.
Chemical Sealants
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Chemical sealers
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Gasket sealer
Room temperature vulcanizing (RTV) sealer
RTV cannot be used in high heat and high
pressure applications
Chemical Sealants
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Cannot be used on fuel system
components
RTV color denotes application and
temperature ranges
Seals
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Used between moving components and their
housings to retain liquids
Withstand high pressure and high
temperatures
Lip seals are most common type
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Some have garter spring to hold seal tight to
surface
Seals
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O-rings
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Rubber ring fits into a groove on moving or
stationary component
Extends beyond groove and pressed against
second component
Seals
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Boots
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Used primarily to protect rather than seal
Most common is CV joint boot
Oil Seal Designs
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Fiber-packing type
Two-piece lip type
One-piece radial type
Oil Seal Designs (Cont’d)
Sealants
Oil Seals
Summary
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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
Summary
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Gaskets serve as sealers, spacers, wear
indicators, and vibration dampers.
General recommendations for installing
gaskets include the following:
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Never reuse old ones.
Clean all mating surfaces.
Use sealants properly.
Summary (Cont’d)
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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.