Ford Thunderbird Manual page 14

03-oo- 13
SERVICE PROCEDURES (Continued}
Valve Spring Retainer and Valve Spring
Retainer Keys
•
Check for proper seating of valve spring retainer
key (6518) on valve stem and in valve spring
retainer (6514).
Valves and Cylinder Head
•
Check the head gasket (6051) for proper
installation.
• Check for plugged oil drain back holes.
•
Check for worn or damaged valve tips.
•
Check for missing or damaged guide-mounted valve
stem seal (6571 ).
•
Check collapsed valve tappet gap (hydraulic valve
tappet applications).
•
Check installed valve spring height.
•
Check for missing or worn valve spring seats (if
equipped).
Static checks (engine off) are to be made on the
engine prior to the dynamic procedure.
Valve Train Analysis-Dynamic
•
Start the engine and, while idling, check for proper
operation of all parts. Check the following:
Rocker Arm
•
Check for plugged oil in rocker arms (6564) or
cylinder head (6049).
•
Check for proper overhead valve train lubrication.
If insufficient oiling is suspected, accelerate the engine
to 1200 rpm ± 100 rpm with the transmission in
NEUTRAL and the engine at normal operating
temperature. Oil should spurt from the rocker arm oil
holes such that valve tips and rocker arms are well
oiled and I or, with the valve covers (6582) off, oil
splash may overshoot rocker arms. If oiling is
insufficient for this to occur, check oil passages for
blockage.
Push Rods
• Check for bent push rods {6565) and restriction in
oil passage.
Positive Rotator and Valve Spring Retainer
Keys
4.6L Engine
•
Check for proper operation of positive rotator.
Valves and Cylinder Head
•
Check for plugged oil drain back holes.
•
Check for missing or damaged valve stem seals
{6571) or guide mounted valve stem seals.
•
Check for plugged oil metering orifice in cylinder
head oil reservoir {4.6L engine only).
Engine-Service
If insufficient oiling is suspected, check oil passages
for blockage, then accelerate the engine to 1200 rpm
with the transmission in NEUTRAL and the engine at
normal operating temperature. Oil should spurt from
the rocker arm oil holes such that valve tips and
rocker arms are well oiled. With the valve covers off,
some oil splash may overshoot rocker arms.
Camshaft Lobe L
Check the lift of each lobe in consecutive order and
make a note of the readings.
1. Remove valve covers {6582).
Remove rocker arm seat bolts, rocker arm seat
2.
{6A528) and rocker arms {6564).
3. Make sure valve tappet {6500) is seated against
camshaft {6250). Install Dial Indicator with
Bracketry TOOL -420 1-c or equivalent
socket adapter of indicator is on top of valve
tappet or Cup Shaped Adapter TOOL -6565-AB
or equivalent is on top of push rod {6565) and in
same plane as valve tappet push rod movement.
Typical Engine With Push Rods
4.
Remove spark plugs {12405).
5. Connect an auxiliary starter switch in starting
circuit. Crank engine with ignition switch in OFF
position. Bump crankshaft {6303) over until valve
tappet is on base circle of camshaft lobe. Zero
the dial indicator. At this point, valve tappet will
be in its lowest position. If checking during engine
assembly, turn crankshaft using a socket or
ratchet.
6. Continue to rotate crankshaft slowly until valve
tappet is in fully-raised position {highest indicator
reading).
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1997 Thunderbird, Cougar July 1 996
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