2003 FORD MUSTANG Workshop Manual

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Page 849 of 4378

FORD MUSTANG 2003 Workshop Manual 4. WORN RINGS OR DILUTED OIL: When the engine is accelerated (dotted needle), the needle
drops to 0 kPa (0 in- Hg). Upon deceleration, the needle runs slightly above 74 kPa (22 in- Hg).
5. STICKING

4. WORN RINGS OR DILUTED OIL: When the engine is accelerated (dotted needle), the needle
drops to 0 kPa (0 in- Hg). Upon deceleration, the needle runs slightly above 74 kPa (22 in- Hg).
5. STICKING VALVES: When the needle (dotted) remains steady at a normal vacuum but occasionally flicks (sharp, fast movement) down and back about 13 kPa (4 in- Hg), one or more
valves may be sticking.
6. BURNED OR WARPED VALVES: A regular, evenly- spaced, downscale flicking of the needle
indicates one or more burned or warped valves. Insufficient hydraulic lash adjuster or hydraulic
lash adjuster (HLA) clearance will also cause this reaction.
7. POOR VALVE SEATING: A small but regular downscale flicking can mean one or more valves are not seating.
8. WORN VALVE GUIDES: When the needle oscillates over about a 13 kPa (4 in- Hg) range at idle
speed, the valve guides could be worn. As engine speed increases, the needle will become
steady if guides are responsible.
9. WEAK VALVE SPRINGS: When the needle oscillation becomes more violent as engine rpm is increased, weak valve springs are indicated. The reading at idle could be relatively steady.
10. LATE VALVE TIMING: A steady but low reading could be caused by late valve timing.
11. IGNITION TIMING RETARDING: Retarded ignition timing will produce a steady but somewhat low reading.
12. INSUFFICIENT SPARK PLUG GAP: When spark plugs are gapped too close, a regular, small pulsation of the needle can occur.
13. INTAKE LEAK: A low, steady reading can be caused by an intake manifold or throttle body gasket leak.
14. BLOWN HEAD GASKET: A regular drop of fair magnitude can be caused by a blown head gasket or warped cylinder head- to-cylinder block surface.
15. RESTRICTED EXHAUST SYSTEM: When the engine is first started and is idled, the reading may be normal, but as the engine rpm is increased, the back pressure caused by a clogged
muffler (5230), kinked tail pipe or other concerns will cause the needle to slowly drop to 0 kPa
(0 in-Hg). The needle then may slowly rise. Excessive exhaust clogging will cause the needle to
drop to a low point even if the engine is only idling.
16. When vacuum leaks are indicated, search out and correct the cause. Excess air leaking into the system will upset the fuel mixture and cause concerns such as rough idle, missing on
acceleration or burned valves. If the leak exists in an accessory unit such as the power brake
booster (2005), the unit will not function correctly. Always fix vacuum leaks.
Excessive Engine Oil Consumption
The amount of oil an engine uses will vary with the way the vehicle is driven in addition to normal
engine- to-engine variation. This is especially true during the first 16,100 km (10,000 miles) when a new
engine is being broken in or until certain internal engine components become conditioned. Vehicles
used in heavy- duty operation may use more oil. The following are examples of heavy- duty operation:
z trailer towing applications
z severe loading applications
z sustained high speed operation Klj . 12 ba
172003 Mustang Workshop Manual
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Page 850 of 4378

FORD MUSTANG 2003 Workshop Manual Engines need oil to lubricate the following internal components:
�zcylinder block cylinder walls
�z pistons and piston, pin and rings (6102)
�z intake and exhaust valve stems
�z intake and exhaust

Engines need oil to lubricate the following internal components:
zcylinder block cylinder walls
z pistons and piston, pin and rings (6102)
z intake and exhaust valve stems
z intake and exhaust valve guides
z all internal engine components
When the pistons move downward, a thin film of oil is left on the cylinder walls. As the vehicle is
operated, some oil is also drawn into the combustion chambers past the intake and exhaust valve
stem seals and burned.
The following is a partial list of conditions that can affect oil consumption rates:
zengine duty cycle
z operator driving habits
z ambient temperature
z quality and viscosity of the oil
Operation under varying conditions can frequently be misleading. A vehicle that has been run for
several thousand miles on short trips or in below- freezing ambient temperatures may have consumed
a "normal" amount of oil. However, when checking the engine oil level, it may measure up to the FULL
or MAX on the oil level dipstick due to dilution (condensation and fuel) in the engine crankcase. The
vehicle might then be driven at high speeds on the highway where the condensation and fuel boil off.
The next time the engine oil is checked, it may appear that a liter (quart) of oil was used in about 160
km (100 miles). This perceived 160 km (100 miles) per liter (quart) oil consumption rate causes
customer concern even though the actual overall oil consumption rate is about 2,400 km (1,500 miles)
per liter (quart).
Make sure the selected engine oil meets the current recommended API performance category with
SAE viscosity grade as shown in the vehicle Owner's Guide. It is also important that the engine oil is
changed at the intervals specified. Refer to the vehicle Owner's Guide.
Oil Pressure Test
1. Disconnect and remove the oil pressure sensor (9278) from the engine.
2. Connect the Oil Pressure Gauge to the oil pressure sender oil galley port.
3. Run the engine until normal operating temperature is reached.
4. Run the engine at the specified rpm and record the gauge reading.
5. The oil pressure should be within specifications; refer to the specification chart in the appropriate engine section.
6. If the pressure is not within specification, check the following possible sources: zinsufficient oil
z oil leakage
z worn or damaged oil pump
z oil pump screen cover and tube (6622)
z excessive main bearing clearance Klj . 13 ba
172003 Mustang Workshop Manual
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Page 851 of 4378

FORD MUSTANG 2003 Workshop Manual �z
excessive connecting rod bearing clearance
Valve Train Analysis— Engine Off—Valve Cover Removed
Check for damaged or severely worn parts and correct assembly. Make sure correct parts are used

Page 852 of 4378

FORD MUSTANG 2003 Workshop Manual Valve Train Analysis—
Engine Running
�z Start the engine and, while idling, check for correct operation of all parts. Check the following:
Valve Train Analysis— Engine Running, Valves and Cylind

Valve Train Analysis—
Engine Running
z Start the engine and, while idling, check for correct operation of all parts. Check the following:
Valve Train Analysis— Engine Running, Valves and Cylinder Head
z Check for plugged oil drain back holes.
z Check for missing or damaged valve stem seals or guide mounted valve stem seals.
z Check for a plugged oil metering orifice in the cylinder head oil reservoir (4.6L engine only).
If insufficient oiling is suspected, check oil passages for blockage, then accelerate the engine to 1,200
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 camshaft roller followers are well oiled.
With the valve covers (6582) off, some oil splash may overshoot camshaft roller followers.
Valve Train Analysis— Engine Running, Camshaft Lobe Lift— OHC Engines
Check the lift of each camshaft lobe in consecutive order and make a note of the readings. 1. Remove the valve covers.
2. Remove the spark plugs.
3. Install the Dial Indicator Gauge with Holding Fixture so the rounded tip of indicator is on top of the camshaft lobe and on the same plane as the valve tappet.
4. Rotate the crankshaft using a breaker bar and socket attached to the crankshaft pulley retainer bolt. Rotate the crankshaft until the base circle of the camshaft lobe is reached.
5. Zero the dial indicator. Continue to rotate the crankshaft until the (1) high- lift point of the
camshaft lobe is in the fully- raised position (highest indicator reading).
6. To check the accuracy of the original indicator reading, continue to rotate crankshaft until the (2) base circle is reached. The indicator reading should be zero. If zero reading is not obtained,
repeat Steps 1 through 6.
7. NOTE: If the lift on any lobe is below specified service limits, install a new camshaft, and new
camshaft roller followers.
Remove the Dial Indicator Gauge with Holding Fixture.
8. Install the spark plugs. Klj . 15 ba
172003 Mustang Workshop Manual
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Page 853 of 4378

FORD MUSTANG 2003 Workshop Manual 9. Install the valve covers.
Valve Train Analysis— Engine Running, Camshaft Lobe Lift— Push Rod Engine
Check the lift of each lobe in consecutive order and make a note of the readings. 1. Remov

Page 854 of 4378

FORD MUSTANG 2003 Workshop Manual �z
incorrectly functioning valve tappet
�z air in lubrication system
�z excessive valve guide wear
�z low oil pressure
Excessive collapsed valve tappet gap can be caused by loose rocker arm seat b

Page 855 of 4378

FORD MUSTANG 2003 Workshop Manual GENERAL PROCEDURES
Sprockets
1. WARNING: To avoid the possibility of personal injury or damage to the vehicle, do
not operate the engine with the hood open until the fan blade has been examined fo

Page 856 of 4378

FORD MUSTANG 2003 Workshop Manual GENERAL PROCEDURES
Rocker Arms —
Cleaning
1. Clean all parts thoroughly. Make sure all oil passages are open.
2. Make sure oil passage in the push rod/valve tappet end of the rocker arm (6564) is

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