GMC 1989 Light Duty Truck, Руководство по ремонту, Страница: 336 / 998

6A-2 GENERAL ENGINE MECHANICAL
GENERAL INFORMATION
STATEMENT ON
CLEANLINESS AND CARE
• An engine is a combination of many machined,
honed, polished and lapped surfaces with very fine
tolerances.
• Whenever valve train components, cylinder head,
cylinder, crankshaft, or connecting rod components
are removed for service, they should be retained in
order. At the time of installation, they should be
installed in the same locations and with the same
mating surfaces as when removed.
• Any tim e air cleaner, carburetor, or TBI unit is
removed, the intake opening must be covered. If a
diesel engine is being serviced, the recommended
cover (J 29664-2) should be used. This will protect
against the entrance of foreign material which could
follow the intake passage into the cylinder and
ca use e x te n sive d am ag e w hen the e n g in e is
started.
• When any internal engine parts are serviced, care
and cleanliness are important. A liberal coating of
engine oil should be applied to friction areas during
assembly to protect and lubricate the surfaces on
initial operation. Throughout this section, it should
be understood that proper cleaning and protection
of machined surfaces and friction areas is part of
the repair procedure. This is considered standard
shop practice even if not specifically stated.
• On diesel engines, w henever the fuel injection
pump or lines are removed or disconnected, care
must be taken to prevent the entry of dirt into the
pump, lines, and injectors. The entry of even small
amounts of dirt or other foreign material into the fuel
injection system may cause serious damage.
USE OF RTV SEALER
AND ANAEROBIC
GASKET ELIMINATOR
Two types of sealer are commonly used in engines
covered by this m anual. These are RTV sealer and
anaerobic “ gasket elim inator” sealer.
It is important that these sealers be applied properly
and in the proper place to prevent oil leaks. THE TWO
TYPES OF SEALER ARE NOT INTERCHANGEABLE.
Use the sealer recommended in the procedure.
• RTV (room temperature vulcanizing) sealer is used
where a non-rigid part is assembled to a rigid part.
Common examples are oil pans and rocker arm
covers.
• Anaerobic gasket elim inator hardens in the absence
of air. This sealer is used where two rigid parts (such
as castings) are assembled together. When two rigid
parts are disassembled and no sealer or gasket is
re a d ily n o tic e a b le , th e p a rts w ere p ro b a b ly
assembled using gasket eliminator.
USING RTV SEALER
1. Do not use RTV when extreme temperatures are
expected, such as exhaust manifold, head gasket or
where gasket elim inator is specified.
2. When separating components sealed with RTV, use
a r u b b e r m a lle t and “ b u m p ” th e p a rt
sideways to shear the RTV sealer. “ B um ping”
should be done at bends or reinforced areas to
prevent distortion of parts. RTV is weaker in shear
(lateral) strength than in tensile (vertical) strength.
Attempting to pry or pull components apart may
result in damage to the part.
3. Surfaces to be resealed must be clean and dry.
Remove all traces of oil and RTV. Clean with a
c h lo rin a te d s o lv e n t such as c a rb u re to r spray
cleaner. Do not use petroleum cleaners such as
mineral spirits; they leave a film onto which RTV will
not stick.
4. Apply RTV to one of the clean surfaces. Use a bead
size as specified in the procedure. Run the bead to
the inside of any bolt holes. Do not allow the sealer
in any blind threaded holes, as it may prevent the
bolt from seating properly or cause damage when
the bolt is tightened.
5. Assemble while RTV is still wet (within 3 minutes).
Do not wait for RTV to skin over.
6
. Torque bolts to specifications. Do not over-torque.
USING ANAEROBIC GASKET ELIMINATOR
1. Clean surfaces to be resealed with a chlorinated
solvent to remove all oil, grease and old material.
2. Apply a continous bead of gasket eliminator to one
flange.
3. Spread bead evenly with your finger to get a uniform
coating on the complete flange.
4. Assemble parts in the normal manner and torque
immediately to specifications.
Im portant
• Anaerobic sealed joints that are partially torqued
and allowed to cure more than five minutes may
result in incorrect shimming of the joint.
REPLACING ENGINE GASKETS
CAUTION: Composite type gaskets are used in
some areas of the engine assem bly. These
gaskets have a thin metal core. Use caution
when removing or handling com posite gaskets
to help avoid personal injury.