Chapter 13 - PowerPoint Presentation

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Chapter 13

Engine Sealing and ReassemblySlide2

Torque Principles

All metals are elastic

Bolts can stretch and compress

Stretch applies clamping force

Too much stretch destroys the bolt

Bolts torqued to yield never return to normalSlide3
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Torque Principles (Cont.)

Most torque values are for dry fasteners

Lubricants increase applied torque

Visually inspect the bolts

Use lubricants or sealers as specified

Tighten in the correct sequence

Ensure proper fastener is usedSlide5

Tightening Sequence ExamplesSlide6

Threads must be clean and undamaged

Use liquid sealant or engine oil on threads

Install bolts in their proper holes

Run a nut over the bolt’s threads by hand

Clean bolt and cylinder block threads with a thread chaser or tap

Tighten bolts to the proper torque specification

Bolt Installation TipsSlide7

Thread CleaningSlide8

Thread Repair

Overtorquing or incorrect threading will strip threads

May be repaired using thread insert or HelicoilSlide9

Torque-To-Yield Bolts

TTY fasteners are designed to stretch when properly tightened

Once at yield point the bolt is permanently stretched

Commonly used as cylinder head bolts

Torqued in stepsSlide10

TTY Bolts (Cont.)Slide11

Knowledge Check

Why is proper tightening of bolts necessary when installing engine components?Slide12

Gaskets

Used to provide a positive seal between parts bolted together

Also act as spacers, wear insulators, and vibration dampers

Gaskets are used on stationary parts

Seals are used with moving partsSlide13

Cut or Soft Gaskets Made of cork, rubber, or paper

Silicone Gasket Material

Three different types

Hard Gaskets

Made of steel, copper, or a composite of metal and fiber

Sealants

Usually in liquid form

Gasket ClassificationsSlide14

Paper/Fiber Gaskets – low temperature/low pressure

Cork Gaskets – not commonly used today

Cut GasketsSlide15

Other Gaskets

Molded Rubber Gaskets – retain flexibility and are durable

May have steel insert around bolt holes

Do not use sealants or adhesives

Hard Gaskets – made from steel and other materials

Used as cylinder head and exhaust manifold gasketsSlide16
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Replacement Gaskets

Available individually or as sets

A full set contains all gaskets necessary for rebuilding an engine

Some components are assembled using form in place gaskets

Check TSBs for updated gasketsSlide18

Never reuse old gaskets

Handle new gaskets carefully

Ensure clean mating surfaces

General Gasket InstallationSlide19

General Gasket Installation

Use the right gasket in the right position

Only use sealants when specified

Make sure all threads are clean and undamagedSlide20

Head Gaskets

Seals combustion, coolant, and oil

Exposed to very low temperatures to combustion temps of 2000 – 4000 °F

Seals vacuum and combustion pressures (1000 psi peak pressures)

Allows for movement between head and block

Most late model engines use MLS gaskets

Specific Engine GasketsSlide21

MLS GasketSlide22

Common Head Gasket Failure

Preignition/Detonation

Incorrect timing or mixture, vacuum leak, faulty cooling system

Engine Overheating

Improper Installation

Wrong head or block surface finish, incorrect bolt tightening, stretched bolts, improper sealant use, incorrect gasketSlide23
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Specific Engine Gaskets (Cont.)

Manifold Gaskets

Intake, exhaust, or combination

Valve Cover Gaskets

Must seal between different metals or materials

Oil Pan Gaskets

Seal between the block and pan

EGR Valve

Gasket may be used to regulate exhaust flowSlide25

Adhesives

Used only to hold a gasket in place

Do not assembly until adhesive is drySlide26

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

Types of SealantsSlide27

Types of Sealants (Cont.)

General Purpose Sealants

Available in liquid, brush on, or aerosol types

Ensure sealant is O

2

sensor safe

Never use a hard drying sealant on gaskets

Thread Sealants

Used on bolts passing through a liquid passageSlide28

Types of Sealants (Cont.)

Silicone Sealants

Formed-in-place gasket

Applied to mating surfaces

Room Temperature Vulcanizing (RTV) most common

Too much RTV can be squeezed out and into oil systemSlide29

Applying RTVSlide30

Antiseize Compounds

Prevents dissimilar metals from reacting with each other and seizing

Commonly used on aluminum parts

Always follow manufacturer recommendations when using Slide31

Knowledge Check

Technician A says gaskets are used between moving parts of the engine. Technician B says liquid RTV gasket maker can be used in place of any engine gasket. Who is correct?Slide32

Engine Gaskets and SealsSlide33

Used with rotating parts

Three basic types

Fiber-packing

Two-piece lip

One-piece radial

Oil SealsSlide34

Oil Seals (Cont.)Slide35

Two-Piece Lip SealSlide36

Engine Reassembly

Clean and lubricate head bolts

Match head gasket to block

Place head on block and alignment dowels

Torque head bolts in sequence

Lube pushrods and rocker armsSlide37

Timing Belts and Chains

Cam and crank alignment is critical

Follow timing procedures exactly

Ensure the tensioners apply properlySlide38

Methods of Valve

Lash Adjustment

Rocker arms with adjustable pivots

Adjustable push rods

Rocker arms with adjustable screws

Adjustable cam followers

Selective shimsSlide39

Final Assembly Steps

Install various covers, pulleys, and sensors

Ensure coolant drain plugs are installed

Coat sensor O-rings with oil before installing

Install vibration damper onto crankshaft

Make sure manifold mating surfaces are clean and install manifoldsSlide40

Final Assembly Steps (Cont.)

Install the thermostat and housing

Install the flexplate and torque converter or the flywheel and clutch components

Inspect and loosely install motor mounts

Install all other related components as necessarySlide41

Knowledge Check

What are two methods of adjusting valve lash?Slide42

Always refer to the manufacturer’s service informationPrime the oil pump prior to starting the engine

Follow the manufacturer’s computer

relearn procedures if applicable

Engine Installation TipsSlide43

Starting Procedure

Set ignition timing as closely as possible

Fill fuel tank with several gallons of fresh fuel

Start engine and run at 1500 RPM

Run until engine reaches normal operating temperature then shut off

Recheck all adjustmentsSlide44

Break-In Procedure

Test drive at 30 MPH and accelerate to 50 MPH at full throttle

Repeat at least 10 times

Apply loads to engine for short periods

This helps assure the rings seatSlide45

Relearn Procedures

The computer will need to learn the engine condition and make adjustments

Idle and transmission shift schedules will relearn

Reset any memory functions such as the clock and radio presets