Mitsubishi Montero (1991+). Manual - part 109

ENGINE OVERHAUL PROCEDURES - GENERAL INFORMATION 



1991 Mitsubishi Montero

         Engine Overhaul Procedures - General Information

         ALL PISTON ENGINES

         * PLEASE READ THIS FIRST *

         Examples used in this article are general in nature and do

not necessarily relate to a specific engine or system. Illustrations

and procedures have been chosen to guide mechanic through engine

overhaul process. Descriptions of processes of cleaning, inspection,

assembly and machine shop practice are included.

         Always refer to appropriate engine overhaul article in the

ENGINES section for complete overhaul procedures and specifications

for the vehicle being repaired.

         ENGINE IDENTIFICATION

         The engine may be identified from its Vehicle Identification

Number (VIN) stamped on a metal tab. Metal tab may be located in

different locations depending on manufacturer. Engine identification

number or serial number is located on cylinder block. Location varies

with manufacturer.

         INSPECTION PROCEDURES

         * PLEASE READ THIS FIRST *

NOTE:    Always refer to appropriate engine overhaul article in the

         ENGINES section for complete overhaul procedures and

         specifications for the vehicle being repaired.

         GENERAL

         Engine components must be inspected to meet manufacturer’s

specifications and tolerances during overhaul. Proper dimensions and

tolerances must be met to obtain proper performance and maximum engine

life.

         Micrometers, depth gauges and dial indicator are used for

checking tolerances during engine overhaul. Magnaflux, Magnaglo, dye-

check, ultrasonic and x-ray inspection procedures are used for parts

inspection.

         MAGNETIC PARTICLE INSPECTION

         Magnaflux & Magnaglo

         Magnaflux is an inspection technique used to locate material

flaws and stress cracks. The part in question is subjected to a strong

magnetic field. The entire part, or a localized area, can be

magnetized. The part is coated with either a wet or dry material that

contains fine magnetic particles.

         Cracks which are outlined by the particles cause an

interruption in the magnetic field. The dry powder method of Magnaflux

can be used in normal light. A crack will appear as an obvious bright

line.

         Fluorescent liquid is used in conjunction with a blacklight

in a second Magnaflux system called Magnaglo. This type of inspection

demands a darkened room. The crack will appear as a glowing line in

this process. Both systems require complete demagnetizing upon

completion of the inspection. Magnetic particle inspection applies to

ferrous materials only.

         PENETRANT INSPECTION

         Zyglo

         The Zyglo process coats the material with a fluorescent dye

penetrant. The part is often warmed to expand cracks that will be

penetrated by the dye. When the coated part is subjected to inspection

with a blacklight, a crack will glow brightly.   Developing solution

is often used to enhance results. Parts made of any material, such as

aluminum cylinder heads or plastics, may be tested using this process.

         Dye Check

         Penetrating dye is sprayed on the previously cleaned

component. Dye is left on component for 5-45 minutes, depending upon

material density. Component is then wiped clean and sprayed with a

developing solution. Surface cracks will show up as a bright line.

         ULTRASONIC INSPECTION

         If an expensive part is suspected of internal cracking,

Ultrasonic testing is used. Sound waves are used for component

inspection.

         X-RAY INSPECTION

         This form of inspection is used on highly stressed

components. X-ray inspection maybe used to detect internal and

external flaws in any material.

         PRESSURE TESTING

         Cylinder heads can be tested for cracks using a pressure

tester. Pressure testing is performed by plugging all but one of the

holes in the head and injecting air or water into the open passage.

Leaks are indicated by the appearance of wet or damp areas when using

water. When air is used, it is necessary to spray the head surface

with a soap solution. Bubbles will indicate a leak. Cylinder head may

also be submerged in water heated to specified temperature to check

for cracks created during heat expansion.

         CLEANING PROCEDURES

         * PLEASE READ THIS FIRST *

NOTE:    Always refer to appropriate engine overhaul article in the

         ENGINES section for complete overhaul procedures and

         specifications for the vehicle being repaired.

         GENERAL

         All components of an engine do not have the same cleaning

requirements. Physical methods include bead blasting and manual

removal. Chemical methods include solvent blast, solvent tank, hot

tank, cold tank and steam cleaning of components.

         BEAD BLASTING

         Manual removal of deposits may be required prior to bead

blasting, followed by some other cleaning method. Carbon, paint and

rust may be removed using bead blasting method. Components must be

free of oil and grease prior to bead blasting. Beads will stick to

grease or oil soaked areas causing area not to be cleaned.

         Use air pressure to remove all trapped residual beads from

components after cleaning. After cleaning internal engine parts made

of aluminum, wash thoroughly with hot soapy water. Component must be

thoroughly cleaned as glass beads will enter engine oil resulting in

bearing damage.

         CHEMICAL CLEANING

         Solvent tank is used for cleaning oily residue from

components. Solvent blasting sprays solvent through a siphon gun using

compressed air.

         The hot tank, using heated caustic solvents, is used for

cleaning ferrous materials only. DO NOT clean aluminum parts such as

cylinder heads, bearings or other soft metals using the hot tank.

After cleaning, flush parts with hot water.

         A non-ferrous part will be ruined and caustic solution will

be diluted if placed in the hot tank. Always use eye protection and

gloves when using the hot tank.

         Use of a cold tank is for cleaning of aluminum cylinder

heads, carburetors and other soft metals. A less caustic and unheated

solution is used. Parts may be lift in the tank for several hours

without damage. After cleaning, flush parts with hot water.

         Steam cleaning, with boiling hot water sprayed at high

pressure, is recommended as the final cleaning process when using

either hot or cold tank cleaning.

         COMPONENT CLEANING

         * PLEASE READ THIS FIRST *

NOTE:    Always refer to appropriate engine overhaul article in the

         ENGINES section for complete overhaul procedures and

         specifications for the vehicle being repaired.

         SHEET METAL PARTS

         Examples of sheet metal parts are the rocker covers, front

and side covers, oil pan and bellhousing dust cover. Glass bead

blasting or hot tank may be used for cleaning.

         Ensure all mating surfaces are flat. Deformed surfaces should

be straightened. Check all sheet metal parts for cracks and dents.

         INTAKE & EXHAUST MANIFOLDS

         Using  solvent cleaning or bead blasting, clean manifolds for

inspection. If the intake manifold has an exhaust crossover, all

carbon deposits must be removed. Inspect manifolds for cracks, burned

or eroded areas, corrosion and damage to fasteners.

         Exhaust heat and products of combustion cause threads of

fasteners to corrode. Replace studs and bolts as necessary. On "V"

type intake manifolds, the sheet metal oil shield must be removed for

proper cleaning and inspection. Ensure that all manifold parting

surfaces are flat and free of burrs.

         CYLINDER HEAD REPLACEMENT

         * PLEASE READ THIS FIRST *

NOTE:    Always refer to appropriate engine overhaul article in the

         ENGINES section for complete overhaul procedures and

         specifications for the vehicle being repaired.

         REMOVAL

         Remove intake and exhaust manifolds and valve cover. Cylinder

head and camshaft carrier bolts (if equipped), should be removed only

when the engine is cold. On many aluminum cylinder heads, removal

while hot will cause cylinder head warpage. Mark rocker arm or

overhead cam components for location.

         Remove rocker arm components or overhead cam components.

Components must be installed in original location. Individual design

rocker arms may utilize shafts, ball-type pedestal mounts or no rocker

arms. For all design types, wire components together and identify

according to the corresponding valve. Remove cylinder head bolts.

Note length and location. Some applications require cylinder head

bolts be removed in proper sequence to prevent cylinder head damage.

See Fig. 1. Remove cylinder head.

Fig. 1:  Typical Cylinder Head Tightening or Loosening Sequence

This Graphic For General Information Only

         INSTALLATION

         Ensure all surfaces and head bolts are clean. Check that head

bolt holes of cylinder block are clean and dry to prevent block damage

when bolts are tightened. Clean threads with tap to ensure accurate

bolt torque.

         Install head gasket on cylinder block. Some manufacturer’s

may recommend sealant be applied to head gasket prior to installation.

Note that all holes are aligned. Some gasket applications may be

marked so certain area faces upward. Install cylinder head using care

not to damage head gasket. Ensure cylinder head is fully seated on

cylinder block.

         Some applications require head bolts be coated with sealant

prior to installation. This is done if head bolts are exposed to water

passages. Some applications require head bolts be coated with light

coat of engine oil.