Volkswagen Corrado (1993 year). Manual - part 133

 

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Volkswagen Corrado (1993 year). Manual - part 133

 

 

ENGINE OVERHAUL PROCEDURES - GENERAL INFORMATION 

         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

ENGINE OVERHAUL PROCEDURES - GENERAL INFORMATION 

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

ENGINE OVERHAUL PROCEDURES - GENERAL INFORMATION 

         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.

ENGINE OVERHAUL PROCEDURES - GENERAL INFORMATION 

         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.
         Install head bolts. Head bolts should be tightened in proper
steps and sequence to specification. See Fig. 1. Install remaining
components. Tighten all bolts to specification. Adjust valves if
required. See VALVE ADJUSTMENT in this article.

NOTE:    Some manufacturers require that head bolts be retightened
         after specified amount of operation. This must be done to
         prevent head gasket failure.

         VALVE ADJUSTMENT

         Engine specifications will indicate valve train clearance and
temperature at which adjustment is to be made on most models. In most
cases, adjustment will be made with a cold engine. In some cases, both
a cold and a hot clearance will be given for maintenance convenience.
         On some models, adjustment is not required. Rocker arms are
tightened to specification and valve lash is automatically set. On
some models with push rod actuated valve train, adjustment is made at
push rod end of rocker arm while other models do not require
adjustment.
         Clearance will be checked between tip of rocker arm and tip
of valve stem in proper sequence using a feeler gauge. Adjustment is
made by rotating adjusting screw until proper clearance is obtained.
Lock nut is then tightened. Engine will be rotated to obtain all valve
adjustments to manufacturer's specifications.

 

 

 

 

 

 

 

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