CH13 engine sealing and reassembly STUDENT VERSION rev

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Chapter 13

Engine Sealing and Reassembly

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 normal

Torque Principles (cont’d)

• 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 used

Bolt Installation Tips

• 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

Thread Cleaning

• Gaskets are used on stationary parts.

• Seals are used with moving parts

General Gasket Installation

• Never reuse old gaskets

• Handle new gaskets carefully

• Ensure clean mating surfaces

• Use the right gasket in the right position

• Only use sealants when specified

• Make sure all threads are clean and

undamaged

• Used only to hold a gasket in place

• Do not assembly until adhesive is dry

Types of Sealants (cont’d)

• General Purpose Sealants

– Available in liquid, brush on, or aerosol types – Ensure sealant is O2 sensor safe

– Never use a hard drying sealant on gaskets

• Thread Sealants

– Used on bolts passing through a liquid passage

Types of Sealants (cont’d)

• 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 system

Antiseize Compounds

• Prevents dissimilar metals from reacting with each other and seizing

• Commonly used on aluminum parts

• Always follow manufacturer

recommendations when using

Oil Seals

• Used with rotating parts

• Three basic types

– Fiber-packing

– Two-piece lip

– One-piece radial

Oil Seals (Cont’d)

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 arms

Timing Belts and Chains

• Cam and crank alignment is critical

• Follow timing procedures exactly

• Ensure the tensioners apply properly

Methods of Valve Lash Adjustment

• Rocker arms with adjustable pivots

• Adjustable push rods

• Rocker arms with adjustable screws

• Adjustable cam followers

• Selective shims

Adjusting Valve Lash

Engine Installation Tips

• Always refer to the manufacturer’s service information

• Prime the oil pump prior to starting the

engine

• Follow the manufacturer’s computer

relearn procedures if applicable

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 adjustments

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 seat

• Reset any memory functions such as the

clock and radio presets