Mitsubishi Montero (1998+). Manual - part 141

than .010" (.25 mm) from tip. Chamfer sharp edge of reground valve

tip. Recheck valve stem installed height.

         VALVE STEM OIL SEALS

         Valve stem oil seals must be installed on valve stem. See

Fig. 2. Seals are needed due to pressure differential at the ends of

valve guides. Atmospheric pressure above intake guide, combined with

manifold vacuum below guide, causes oil to be drawn into the cylinder.

         Exhaust guides also have pressure differential created by

exhaust gas flowing past the guide, creating a low pressure area. This

low pressure area draws oil into the exhaust system.

         Replacement (On Vehicle)

         Mark rocker arm or overhead cam components for location.

Remove rocker arm components or overhead cam components. Components

must be installed in original location. Remove spark plugs. Valve stem

oil seals may be replaced by holding valves against seats using air

pressure.

         Air pressure must be installed in cylinder using an adapter

for spark plug hole. An adapter can be constructed by welding air hose

connection to spark plug body with porcelain removed.

         Install adapter in spark plug hole. Apply a minimum of 140

psi (9.8 kg/cm ) to adapter. Air pressure should hold valve closed. If

air pressure does not hold valve closed, check for damaged or bent

valve. Cylinder head must be removed for service.

         Using valve spring compressor, compress valve springs. Remove

valve locks. Carefully release spring compressor. Remove retainer or

rotator and valve spring. Remove valve stem oil seal.

         If oversized valves have been installed, oversized oil seals

must be used. Coat valve stem with engine oil. Install protective

sleeve over end of valve stem. Install new oil seal over valve stem

and seat on valve guide. Remove protective sleeve. Install spring

seat, valve spring and retainer or rotator. Compress spring and

install valve locks. Remove spring compressor. Ensure valve locks

are fully seated.

         Install rocker arms or overhead cam components. Tighten all

bolts to specification. Adjust valves if required. Remove adapter.

Install spark plugs, valve cover and gasket.

         VALVE SPRING INSTALLED HEIGHT

         Valve spring installed height should be checked during

reassembly. Measure height from lower edge of valve spring to the

upper edge. DO NOT include valve spring seat or retainer. Distance

must be within specifications. If valves and/or seats have been

ground, a valve spring shim may be required to correct spring height.

See Fig. 12.

Fig. 12:  Measuring Valve Spring Installed Height - Typical

This Graphic For General Information Only

         ROCKER ARMS & ASSEMBLIES

         Rocker Studs

         Rocker studs are either threaded or pressed in place.

Threaded studs are removed by locking 2 nuts on the stud. Unscrew the

stud by turning the jam nut. Coat the stud threads with Loctite and

install. Tighten to specification.

         Pressed in stud can be removed using a stud puller. Ream the

stud bore to proper specification and press in a new oversize stud.

Pressed in studs are often replaced by cutting threads in the stud

bore to accept a threaded stud.

         Rocker Arms & Shafts

         Mark rocker arms for location. Remove rocker arm retaining

bolts. Remove rocker arms. Inspect rocker arms, shafts, bushings and

pivot balls (if equipped) for excessive wear. Inspect rocker arms

for wear in valve stem contact area. Measure rocker arm bushing I.D.

Replace bushings if excessively worn.

         The rocker arm valve stem contact point can be reground,

using special fixture for valve grinding machine. Remove minimum

amount of material as possible. Ensure all oil passages are clear.

Install rocker arms in original locations. Ensure rocker arm is

properly seated in push rod. Tighten bolts to specification. Adjust

valves if required. See VALVE ADJUSTMENT in this article.

         Pushrods

         Remove rocker arms. Mark push rods for location. Remove push

rods. Push rods can be steel or aluminum, solid or hollow. Hollow

pushrods must be internally cleaned to ensure oil passage to the

rocker arms is cleaned. Check the pushrod for damage, such as loose

ends on steel tipped aluminum types.

         Check push rod for straightness. Roll push rod on a flat

surface. Using feeler gauge, check clearance at center. Replace push

rod if bent. The push rod can also be supported at each end and

rotated. A dial indicator is used to detect bends in the push rod.

         Lubricate ends of push rod and install push rod in original

location. Ensure push rod is properly seated in lifter. Install rocker

arm. Tighten bolts to specification. Adjust valves if required. See

VALVE ADJUSTMENT in this article.

         LIFTERS

         Hydraulic Lifters

         Before replacing a hydraulic lifter for noisy operation,

ensure noise is not caused by worn rocker arms or valve tips.

Hydraulic lifter assemblies must be installed in original locations.

Remove the rocker arm assembly and push rod. Mark components for

location. Some applications require intake manifold, or lifter cover

removal. Remove lifter retainer plate (if used). To remove lifters,

use a hydraulic lifter remover or magnet. Different type lifters are

used. See Fig. 13.

Fig. 13:  Typical Hydraulic Valve Lifter Assemblies - Typical

This Graphic For General Information Only

         On sticking lifters, disassemble and clean lifter. DO NOT mix

lifter components or positions. Parts are select-fitted and are not

interchangeable. Inspect all components for wear. Note amount of wear

in lifter body-to-camshaft contact area. Surface must have smooth and

convex contact face. If wear is apparent, carefully inspect cam lobe.

         Inspect push rod contact area and lifter body for scoring

or signs of wear. If body is scored, inspect lifter bore for damage

and lack of lubrication. On roller type lifters, inspect roller for

flaking, pitting, loss of needle bearings and roughness during

rotation.

         Measure lifter body O.D. in several areas. Measure lifter

bore I.D. of cylinder block. Some models offer oversized lifters.

Replace lifter if damaged.

         If lifter check valve is not operating, obstructions may be

preventing it from closing or valve spring may be broken. Clean or

replace components as necessary.

         Check plunger operation. Plunger should drop to bottom of the

body by its own weight when assembled dry. If plunger is not free,

soak lifter in solvent to dissolve deposits.

         Lifter leak-down test can be performed on lifter. Lifter

must be filled with special test oil. New lifters contain special test

oil. Using lifter leak-down tester, perform leak-down test following

manufacturer’s instructions. If leak-down time is not within

specifications, replace lifter assembly.

         Lifters should be soaked in clean engine oil several hours

prior to installation. Coat lifter base, roller (if equipped) and

lifter body with ample amount of Molykote or camshaft lubricant. See

Fig. 13. Install lifter in original location. Install remaining

components. Valve lash adjustment is not required on most hydraulic

lifters. Preload of hydraulic lifter is automatic. Some models may

require adjustment.

         Mechanical Lifters

         Lifter assemblies must be installed in original locations.

Remove rocker arm assembly and push rod. Mark components for location.

Some applications require intake manifold or lifter cover removal.

Remove lifter retainer plate (if used). To remove lifters, use lifter

remover or magnet.

         Inspect push rod contact area and lifter body for scoring or

signs of wear. If body is scored, inspect lifter bore for damage and

lack of lubrication. Note amount of wear in lifter body-to-camshaft

contact area. Surface must have smooth and convex contact face. If

wear is apparent, carefully inspect cam lobe.

         Coat lifter base, roller (if equipped) and lifter body with

ample amount of Molykote or camshaft lubricant. Install lifter in

original location. Install remaining components. Tighten bolts to

specification. Adjust valves. See VALVE ADJUSTMENT in this article.

         PISTONS, CONNECTING RODS & BEARINGS

         * 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.

         RIDGE REMOVAL

         Ridge in cylinder wall must be removed prior to piston

removal. Failure to remove ridge prior to removing pistons will cause

piston damage in piston ring locations.

         With the piston at bottom dead center, place a rag in the

bore to trap metal chips. Install ridge reamer in cylinder bore.

Adjust ridge reamer using manufacturer’s instructions. Remove ridge