remove seats VOLKSWAGEN CORRADO 1990 Repair Manual

1.8L 4-CYL 8-VALVE & 1.8L 4-CYL 16-VALVE
Article Text (p. 13)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:40PM
Right Side - Exhaust Valves.
Left Side - Intake Valves.
NOTE: "Right" and "Left" refer to right and left side of engine
NOT vehicle.
VALVE SEALS & SPRINGS R & I
Valve seals and springs may be removed with cylinder head
installed in vehicle. Remove camshaft as previously described. Mark
and remove lifters. Use compressed air to hold valves closed.
Installation Bar (2036), Spring Compressor (VW 541/1) and Valve Seal
Replacer/Sleeve (10-204/A) are necessary tools for replacing. DO NOT
install valve seal without using sleeve.
VALVE GUIDE R & I
If valve-to-guide clearance is not within specifications,
replace guide(s). See ENGINE SPECIFICATIONS tables at end of this
article. To replace valve guide, press guide out from combustion
chamber side. Press guide in cold cylinder head as far as guide will
go. DO NOT exceed one ton pressure. Ream guides by hand to achieve
proper valve-to-guide clearance.
VALVE SEATS
1) Check valve seats prior to any other cylinder head
service. If valve seats are less than specifications, cylinder head
must be replaced. Insert the valve and hold firmly against the valve
seat. Measure distance of valve stem tip to valve cover mounting
surface. See Fig. 14.Fig. 14: Measuring For Refacing Dimension
Courtesy of Volkswagen United States, Inc.
2) Subtract measured distance from minimum specifications.
See MINIMUM VALVE-TO-CYLINDER HEAD DIMENSION following this paragraph.
The total is maximum refacing allowable for both valve and seat. If
more is required, replace cylinder head assembly or machine valve stem

A/C COMPRESSOR SERVICING
Article Text (p. 14)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:41PM
ring and carbon seal contact surface of shaft seal seat for damage.
Make sure that "O" ring contact surface on front cover is not damaged.
Make sure refrigerant oil is applied to oil seal in shaft seal seat.
Installation
1) To install, reverse removal procedure. Ensure shaft seal
contact surface is free of dirt. Lubricate with refrigerant oil. Cap
end of compressor shaft.
2) Using Guard (KV994C1143), insert shaft seal. Be sure shaft
seal case is aligned with shaft. Apply force to turn seal to left and
right. Ensure shaft seal seats properly in shaft cut-out.
3) Fit "O" ring to outside groove of shaft seal seat. Ensure
"O" ring seats properly. Apply refrigerant oil on contact surfaces and
around shaft seal seat. Lightly coat surface of shaft with refrigerant
oil.
4) Install key on compressor shaft. Using snap ring pliers,
compress retainer ring and fit retainer ring into front cover. Seat
retainer ring firmly in groove. Thoroughly wipe grease or oil from
shaft surface.
5) Connect Installer (KV99412329) to shaft of compressor, and
turn shaft 5 or 6 times in a clockwise direction to seat seal. See
REFRIGERANT OIL & R-12 SPECIFICATIONS chart in this section for system
capacities.
MATSUSHITA ROTARY VANE CLUTCH R & I
Removal & Installation
1) Insert two 5 mm bolts into threaded holes in armature.
Using a screwdriver as lever in between bolts, remove center bolt.
remove armature and shim from shaft.
2) Remove snap ring. Using a puller, remove pulley.
Disconnect electrical leads from field coil. Remove 3 field coil
mounting bolts. Remove field coil. See Fig. 10. To install, reverse
removal procedure.Fig. 10: Exploded View of Rotary Vane Compressor (Matsushita)
Courtesy of Subaru of America. Inc.
NIPPONDENSO TV12 ROTARY VANE CLUTCH R & I

ENGINE OVERHAUL PROCEDURES - GENERAL INFORMATION
Article Text (p. 10)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:44PM
Replacing Valve Guide
Replace valve guide if clearance exceeds specification. Valve
guides are either pressed, hammered or shrunk in place, depending upon
cylinder head design and type of metal used.
Remove valve guide from cylinder head by pressing or tapping
on a stepped drift. See Fig. 8. Once valve guide is installed,
distance from cylinder head to top of valve guide must be checked.
This distance must be within specification.
Aluminum heads are often heated before installing valve
guide. Guide is sometimes chilled in dry ice before installation.
Combination of a heated head and chilled guide insures a tight guide
fit upon assembly. The new guide must be reamed to specification.Fig. 8: Typical Valve Guide Remover & Installer
This Graphic For General Information Only
VALVES & VALVE SEATS
Valve Grinding
Valve stem O.D. should be measured in several areas to
indicate amount of wear. Replace valve if not within specification.
Valve margin area should be measured to ensure that valve can be
grounded. See Fig. 9.Fig. 9: Measuring Valve Head Margin - Typical
This Graphic For General Information Only
If valve margin is less than specification, this will burn
the valves. Valve must be replaced. Due to minimum margin dimensions
during manufacture, some new type valves cannot be reground.
Resurface valve on proper angle specification using valve
grinding machine. Follow manufacturer's instructions for valve
grinding machine. Specifications may indicate a different valve face
angle than seat angle.
Measure valve margin after grinding. Replace valve if not
within specification. Valve stem tip can be refinished using valve

ENGINE OVERHAUL PROCEDURES - GENERAL INFORMATION
Article Text (p. 11)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:44PM
grinding machine.
Valve Lapping
During valve lapping of recent designed valves, be sure to
follow manufacturers recommendations. Surface hardening and materials
used with some valves do not permit lapping. Lapping process will
remove excessive amounts of the hardened surface.
Valve lapping is done to ensure adequate sealing between
valve face and seat. Use either a hand drill or lapping stick with
suction cup attached.
Moisten and attach suction cup to valve. Lubricate valve stem
and guide. Apply a thin coat of fine valve grinding compound between
valve and seat. Rotate lapping tool between the palms or with hand
drill.
Lift valve upward off the seat and change position often.
This is done to prevent grooving of valve seat. Lap valve until a
smooth polished seat is obtained. Thoroughly clean grinding compound
from components. Valve to valve seat concentricity should be checked.
See VALVE SEAT CONCENTRICITY.
CAUTION: Valve guides must be in good condition and free of carbon
deposits prior to valve seat grinding. Some engines contain
an induction hardened valve seat. Excessive material removal
will damage valve seats.
Valve Seat Grinding
Select coarse stone of correct size and angle for seat to be
ground. Ensure stone is true and has a smooth surface. Select correct
size pilot for valve guide dimension. Install pilot in valve guide.
Lightly lubricate pilot shaft. Install stone on pilot. Move stone off
and on the seat approximately 2 times per second during grinding
operation.
Select a fine stone to finish grinding operation. Grinding
stones with 30 and 60 degree angles are used to center and narrow the
valve seat as required. See Fig. 10.Fig. 10: Adjusting Valve Seat Width - Typical
This Graphic For General Information Only

ENGINE OVERHAUL PROCEDURES - GENERAL INFORMATION
Article Text (p. 12)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:44PM
Valve Seat Replacement
Replacement of valve seat inserts is done by cutting out
the old insert and machining an oversize insert bore. Replacement
oversize insert is usually chilled and the cylinder head is sometimes
warmed. Valve seat is pressed into the head. This operation requires
specialized machine shop equipment.
Valve Seat Concentricity
Using dial gauge, install gauge pilot in valve guide.
Position gauge arm on the valve seat. Adjust dial indicator to zero.
Rotate arm 360 degrees and note reading. Runout should not exceed
specification.
To check valve-to-valve seat concentricity, coat valve face
lightly with Prussian Blue dye. Install valve and rotate it on valve
seat. If pattern is even and entire seat is coated at valve contact
point, valve is concentric with the seat.
REASSEMBLY
Valve Stem Installed Height
Valve stem installed height must be checked when new valves
are installed or when valves or valve seats have been ground. Install
valve in valve guide. Measure distance from tip of valve stem to
spring seat. See Fig. 11. Distance must be within specifications.Fig. 11: Measuring Valve Stem Installed Height - Typical
This Graphic For General Information Only
Remove valve and grind valve stem tip if height exceeds
specification. Valve tips are surface hardened. DO NOT remove more
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

ENGINE OVERHAUL PROCEDURES - GENERAL INFORMATION
Article Text (p. 13)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:44PM
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/cmý) 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

TROUBLE SHOOTING - BASIC PROCEDURES
Article Text (p. 32)
1990 Volkswagen Corrado
For Volkswagen Technical Site: http://vw.belcom.ru
Copyright © 1998 Mitchell Repair Information Company, LLC
Thursday, March 23, 2000 09:52PM
Loose rocker arms Retighten rocker arms,
See ENGINES
Excessive valve seat Reface valve seats, See
run-out ENGINES
Missing valve lock Install new valve lock
Excessively worn camshaft Replace camshaft, See
lobes ENGINES
Plugged valve lifter oil Eliminate restriction
holes or replace lifter
Faulty valve lifter check Replace lifter check
ball ball, See ENGINES
Rocker arm nut installed Remove and reinstall
upside down correctly
Valve lifter incorrect for Remove and replace
engine valve lifters
Faulty push rod seat or Replace plunger or push
lifter plunger rodÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄNoisy Valves Improper valve lash Re-adjust valve lash,
See ENGINES
Worn or dirty valve lifters Clean and/or replace
lifters
Worn valve guides Replace valve guides,
See ENGINES
Excessive valve seat or Reface seats or valve
face run-out face
Worn camshaft lobes Replace camshaft, See
ENGINES
Loose rocker arm studs Re-tighten rocker arm
studs, See ENGINES
Bent push rods Replace push rods, See
ENGINES
Broken valve springs Replace valve springs,
See ENGINES
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄBurned,Sticking Weak valve springs or Replace valves and/or
or Broken Valves warped valves springs, See ENGINES
Improper lifter clearance Re-adjust clearance or
replace lifters
Worn guides or improper Replace valve guides,
guide clearance See ENGINES
Out-of-round valve seats Re-grind valve seats
or improper seat width
Gum deposits on valve Remove deposits
stems, seats or guides
Improper spark timing Re-adjust spark timing
ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄBroken Undersize pistons Replace with larger
Pistons/Rings pistons, See ENGINES
Wrong piston rings Replace with correct
rings, See ENGINES
Out-of-round cylinder bore Re-bore cylinder bore