2003 FORD MUSTANG low oil pressure

required to obtain the highest reading.
5. Repeat the test on each cylinder, cranking the engine approximately the same number of compression strokes.
Compression Test— Test Results
The indicated compression pressures are considered within specification if the lowest reading cylinder
is at least 75 percent of the highest reading. Refer to the Compression Pressure Limit Chart.
If one or more cylinders reads low, squirt approximately one tablespoon of engine oil on top of the
pistons in the low- reading cylinders. Repeat the compression pressure check on these cylinders. Compression Test — Interpreting Compression Readings Compression Pressure Limit Chart
Maximum
Pressure Minimum
Pressure Maximum
Pressure Minimum
Pressure Maximum
Pressure Minimum
Pressure Maximum
Pressure Minimum
Pressure 924 kPa
(134 psi) 696 kPa
(101 psi) 1131 kPa
(164 psi) 848 kPa
(123 psi) 1338 kPa
(194 psi) 1000 kPa
(146 psi) 1544 kPa
(224 psi) 1158 kPa
(168 psi) 938 kPa
(136 psi) 703 kPa
(102 psi) 1145 kPa
(166 psi) 855 kPa
(124 psi) 1351 kPa
(196 psi) 1014 kPa
(147 psi) 1558 kPa
(226 psi) 1165 kPa
(169 psi) 952 kPa
(138 psi) 717 kPa
(104 psi) 1158 kPa
(168 psi) 869 kPa
(126 psi) 1365 kPa
(198 psi) 1020 kPa
(148 psi) 1572 kPa
(228 psi) 1179 kPa
(171 psi) 965 kPa
(140 psi) 724 kPa
(106 psi) 1172 kPa
(170 psi) 876 kPa
(127 psi) 1379 kPa
(200 psi) 1034 kPa
(150 psi) 1586 kPa
(230 psi) 1186 kPa
(172 psi) 979 kPa
(142 psi) 738 kPa
(107 psi) 1186 kPa
(172 psi) 889 kPa
(129 psi) 1303 kPa
(202 psi) 1041 kPa
(151 psi) 1600 kPa
(232 psi) 1200 kPa
(174 psi) 933 kPa
(144 psi) 745 kPa
(109 psi) 1200 kPa
(174 psi) 903 kPa
(131 psi) 1407 kPa
(204 psi) 1055 kPa
(153 psi) 1055 kPa
(153 psi) 1207 kPa
(175 psi) 1007 kPa
(146 psi) 758 kPa
(110 psi) 1214 kPa
(176 psi) 910 kPa
(132 psi) 1420 kPa
(206 psi) 1062 kPa
(154 psi) 1627 kPa
(154 psi) 1220 kPa
(177 psi) 1020 kPa
(148 psi) 765 kPa
(111 psi) 1227 kPa
(178 psi) 917 kPa
(133 psi) 1434 kPa
(208 psi) 1075 kPa
(156 psi) 1641 kPa
(238 psi) 1227 kPa
(178 psi) 1034 kPa
(150 psi) 779 kPa
(113 psi) 1241 kPa
(180 psi) 931 kPa
(135 psi) 1448 kPa
(210 psi) 1083 kPa
(157 psi) 1655 kPa
(240 psi) 1241 kPa
(180 psi) 1048 kPa
(152 psi) 786 kPa
(114 psi) 1255 kPa
(182 psi) 936 kPa
(136 psi) 1462 kPa
(212 psi) 1089 kPa
(158 psi) 1669 kPa
(242 psi) 1248 kPa
(181 psi) 1062 kPa
(154 psi) 793 kPa
(115 psi) 1269 kPa
(184 psi) 952 kPa
(138 psi) 1476 kPa
(214 psi) 1103 kPa
(160 psi) 1682 kPa
(244 psi) 1262 kPa
(183 psi) 1076 kPa
(156 psi) 807 kPa
(117 psi) 1282 kPa
(186 psi) 965 kPa
(140 psi) 1489 kPa
(216 psi) 1117 kPa
(162 psi) 1696 kPa
(246 psi) 1269 kPa
(184 psi) 1089 kPa
(158 psi) 814 kPa
(118 psi) 1296 kPa
(188 psi) 972 kPa
(141 psi) 1503 kPa
(218 psi) 1124 kPa
(163 psi) 1710 kPa
(248 psi) 1202 kPa
(186 psi) 1103 kPa
(160 psi) 827 kPa
(120 psi) 1310 kPa
(190 psi) 979 kPa
(142 psi) 1517 kPa
(220 psi) 1138 kPa
(165 psi) 1724 kPa
(250 psi) 1289 kPa
(187 psi) 1110 kPa
(161 psi) 834 kPa
(121 psi) 1324 kPa
(192 psi) 993 kPa
(144 psi) 1631 kPa
(222 psi) 1145 kPa
(166 psi) — —Klj . 8 ba
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1. If compression improves considerably, piston rings are faulty.
2. If compression does not improve, valves are sticking or seating incorrectly.
3. If two adjacent cylinders indicate low compression pressures and squirting oil on each piston
does not increase compression, the head gasket may be leaking between cylinders. Engine oil
or coolant in cylinders could result from this condition.
Use the Compression Pressure Limit Chart when checking cylinder compression so that the
lowest reading is within 75 percent of the highest reading.
Cylinder Leakage Detection
When a cylinder produces a low reading, use of the Engine Cylinder Leak Detection/Air Pressurization
Kit will be helpful in pinpointing the exact cause.
The leakage detector is inserted in the spark plug hole, the piston is brought up to dead center on the
compression stroke, and compressed air is admitted.
Once the combustion chamber is pressurized, a special gauge included in the kit will read the
percentage of leakage. Leakage exceeding 20 percent is excessive.
While the air pressure is retained in the cylinder, listen for the hiss of escaping air. A leak at the intake
valve (6507) will be heard in the throttle body (9E926). A leak at the exhaust valve (6505) can be
heard at the tail pipe. Leakage past the piston rings will be audible at the positive crankcase ventilation
(PCV) connection. If air is passing through a blown head gasket to an adjacent cylinder, the noise will
be evident at the spark plug hole of the cylinder into which the air is leaking. Cracks in the cylinder
block or gasket leakage into the cooling system may be detected by a stream of bubbles in the radiator
(8005).
Oil Consumption Test
The following diagnostic procedure is used to determine the source of excessive internal oil
consumption. 1. NOTE: Oil use is normally greater during the first 16,100 km (10,000 miles) of service. As
mileage increases, oil use generally decreases. Vehicles in normal service should get at least
1,450 km per liter (900 miles per quart) after 16,000 km (10,000 miles) of service. High speed
driving, towing, high ambient temperature and other factors may result in greater oil use.
Define excessive oil consumption, such as the number of miles driven per liter (quart) of oil
used. Also determine customer's driving habits, such as sustained high speed operation,
towing, extended idle and other considerations.
2. Verify that the engine has no external oil leak as described under Engine Oil Leaks in the Diagnosis and Testing portion of this section.
3. Verify that the engine has the correct oil level dipstick (6750).
4. Verify that the engine is not being run in an overfilled condition. Check the oil level at least five minutes after a hot shutdown with the vehicle parked on a level surface. In no case should the
level be above MAX or the letter F in FULL. If significantly overfilled, carry out Steps 6a through
6d.
5. Verify the spark plugs are not oil saturated. If the spark plugs are oil saturated and compression is good it can be assumed the valve seals or valve guides are at fault. Klj . 9 ba
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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
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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
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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 bolts/nuts, incorrect
initial adjustment or wear of valve tappet face, or worn roller valve tappets, push rod (6565), rocker
arm (6564), rocker arm seat or valve tip. With valve tappet collapsed, check gap between the valve tip
and the rocker arm to determine if any other valve train parts are damaged, worn or out of adjustment.
An incorrectly functioning valve tappet can be sticking, caused by contaminants or varnish inside the
tappet. The tappet can have a check valve that is not functioning correctly, which can be caused by an
obstruction, such as dirt or chips that prevent the check valve from closing, or a broken check valve
spring. A tappet with a leakdown time out of specification can cause tappet noise. If no other cause for
noisy valve tappets can be found, the leakdown rate should be checked and new valve tappets
installed if found to be out of specification.
Assembled valve tappets can be tested with Hydraulic Tappet Leakdown Tester to check the leakdown
rate. The leakdown rate specification is the time in seconds for the plunger to move a specified
distance while under a 22.7 kg (50 lb) load.
Air bubbles in the lubrication system will prevent the valve tappet from supporting the valve spring
load. This can be caused by too high or too low an oil level in the oil pan or by air being drawn into the
system through a hole, crack or leaking gasket on the oil pump screen cover and tube. Klj . 17 ba
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4. Inspect for normal burning.
zCheck for light tan or gray deposits on the firing tip.
5. Inspect for pre- ignition, identified by melted electrodes and a possibly damaged insulator.
Metallic deposits on the insulator indicate engine damage. This may be caused by incorrect
ignition timing, wrong type of fuel or the unauthorized installation of a heli- coil insert in place of
the spark plug threads.
zInstall a new spark plug.
6. Inspect for overheating, identified by a white or light gray spots and with bluish- burnt
appearance of electrodes. This is caused by engine overheating, wrong type of fuel, loose spark
plugs, spark plugs with an incorrect heat range, low fuel pump pressure or incorrect ignition
timing.
zInstall a new spark plug. Klj . 2 ba
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A/C compressor bracket-
to-cylinder head stud bolt 25 18 —
Oil level indicator tube-
to-cylinder head bolt 10 — 89
Coolant recovery reservoir bracket-to-
GOP bolts 9 — 80
Motor mount-
to-subframe nuts 115 85 —
Oil pan drain plug 26 19 —
Wire harness bracket to motor mount nut 27 20 —
Steering column pinch bolt 47 35 —
Front subframe-
to-body bolts 90 66 —
Front subframe-
to-shock tower bolts 115 85 —
Oil pan-to-
cylinder block bolts a — — —
Oil pan-to-
transmission bell housing 45 33 —
Main bearing bridge nuts 32 24
Oil pump cover-
to-engine front cover bolts 25 18 —
Oil pump cover-
to-engine front cover bolt 10 89 —
Oil pickup tube-
to-cylinder block bolts 25 18 —
Oil pickup tube-
to-oil pan baffle nut 48 35 —
Flywheel-
to-crankshaft bolts 80 59 —
Wire harness bracket-
to-motor mount stud- nut 27 20 —
Engine ground strap-
to-motor mount nut 27 20 —
Motor mount-
to-motor mount bracket bolts 70 52 —
RH motor mount-
to-motor mount bracket nut 70 52 —
Hood ground strap-
to-hood hinge bolt 12 9 —
Hood hinge nuts 12 9 —
Generator mounting bracket 25 18 —
Power steering pump bracket nuts 8 — 71
Power steering pump bolts 25 18 —
Valve tappet guide plate bolts 12 9 —
Generator positive cable nut 10 — 89
Power steering pressure tube to pump nut 40 30 —
Accelerator cable bracket-
to-intake manifold bolts 10 — 89
42-
pin connector bolt 10 — 89
Transmission oil cooler tube bracket-
to-motor mount bracket nut 27 20
Torque converter-
to-flywheel nuts 36 27 —
Engine-
to-transmission bolts 40 30 —
Engine mount bracket-
to-engine bolts 70 52 —
Engine mount bracket-
to-engine nuts 70 52 —
Water pump pulley bolts 25 18 —
Oil filter
b — — —
Upper intake manifold-
to-lower intake manifold bolts a — — —
Lower intake manifold-
to-cylinder head bolts a — — —
Rocker arm pivot-
to-cylinder head bolts a — — — Klj . 5 ba
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Cylinder Block and Lower End Components 9 18801 Radio ignition interference capacitor
10 12281 Ignition wire set —
LH 11 18696 Tube assembly
12 9424 Intake manifold (lower)
13 9439 Intake manifold gasket —
RH 14 9439 Intake manifold gasket —
LH 15 9A424 Intake manifold seal (rear)
16 6A008 Cylinder head-
to-block dowel 17 6010 Cylinder block
18 6A373 Engine rear plate (automatic transmission)
19 6375 Flywheel (automatic transmission)
20 6375 Flywheel (manual transmission)
21 6A372 Engine rear plate (manual transmission)
22 6723 Oil pan rear seal
23 6675 Oil pan
24 7120 Pilot bushing
25 9278 Oil pressure sensor
26 9B339 Oil pressure sensor fitting
27 9A424 Intake manifold seal (front)
28 18663 Heater water outlet tube
29 8255 Thermostat housing-
to-intake manifold gasket 30 8592 Water outlet connection
31 9875 Water thermostat
32 9D475 EGR valve
33 9H465 Vacuum control solenoid
34 9723 Accelerator cable bracket
35 9E936 Throttle body gasket
36 9J433 EGR transducer
37 9E498 Vacuum hose
38 12280 Ignition wire set —
RH Klj . 5 ba
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