2003 FORD MUSTANG compression ratio

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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SPECIFICATIONS
SECTION 303-
01A: Engine — 3.8L 2003 Mustang Workshop Manual General Specifications
Item Specification
Lubricants and Sealants
SAE 5W-
20 Premium Synthetic Blend Motor Oil
XO- 5W20- QSP WSS-
M2C153- H Gasket and Trim Adhesive F3AZ-19B508-
AA ESE-
M2G52- A Pipe Sealant with Teflon® D8AZ-19554-
A WSK-
M2G350- A2 Silicone Gasket and Sealant F7AZ-19554-
EA WSE-
M4G323- A4 Metal Surface Cleaner F4AZ-19A536-
RA WSE-
M5B392- A Engine
Displacement 3.8L
Number of cylinders 6
Bore 96.8325 mm (3.81 in)
Stroke 86.0 mm (3.39 in)
Firing order 1-4-2-5-3-
6 Oil pressure (hot 2,500 rpm) 40-
125 psi Oil capacity 5 quarts w/filter change
Compression ratio —
Cylinder Head and Valve Train
Cylinder head gasket surface flatness 0.18 mm (0.007 in)
Combustion chamber volume 61.5-
64.5 cc Valve arrangement (front to rear) —
Valve guide bore diameter 7.015-
7.044 mm (0.276- 0.277 in) Valve stem diameter —
intake 6.955-
6.988 mm (0.2738- 0.2751 in) Valve stem diameter —
exhaust 6.929-
6.962 mm (0.2728- 0.2741 in) Valve stem diameter —
oversize (intake) 9.075-
9.055 mm (0.3573- 0.3565 in) Valve stem diameter —
oversize (exhaust) 9.063-
9.043 mm (0.3568- 0.3560 in) Valve stem diameter —
oversize (intake) 9.456-
9.436 mm (0.3723- 0.3715 in) Valve stem diameter —
oversize (exhaust) 9.444-
9.424 mm (0.3718- 0.3710 in) Valve stem-
to-guide clearance — intake 0.020-
0.069 mm (0.045- 0.090 in) Valve stem-
to-guide clearance — exhaust 0.038-
0.083 mm (0.0015- 0.0033 in) Valve head diameter —
intake 47.27 mm (1.86 in)
Valve head diameter —
exhaust 37.1 mm (1.46 in)
Valve face runout 0.05 mm (0.002 in)
Valve face angle 45.675 degrees
Valve seat width 1.5-
2.0 mm (0.06- 0.08 in) Valve seat runout (T.I.R.) 0.076 mm (0.003 in) Klj . 1 ba
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Valve seat angle 44.75 degrees
Valve spring free length —
Valve spring squareness —
Valve spring compression pressure —
valve
open (without damper) 1000 N (224 lbs) @ 29.2 mm (1.16 in)
Valve spring compression pressure —
valve
closed (without damper) 350 N (79 lbs) @ 40.7 mm (1.62 in)
Valve spring installed height 40.7 mm (1.62 in)
Valve spring installed pressure —
Rocker arm ratio 1.73
Hydraulic Lash Adjuster
Diameter 22.195-
22.212 mm (0.8738- 0.8745 in) Clearance-
to-bore 0.018-
0.068 mm (0.0007- 0.0027 in) Service limit 0.127 mm (0.005 in)
Hydraulic leakdown rate a
Collapsed lash adjuster gap —
Camshaft
Theoretical valve lift @ 0 lash —
intake 11.30 mm (0.45 in)
Theoretical valve lift @ 0 lash —
exhaust 11.47 mm (0.45 in)
Lobe lift —
intake 6.53 mm (0.257 in)
Lobe lift —
exhaust 6.57 mm (0.259 in)
Allowable lobe lift loss 0.127 mm (0.005 in)
Journal diameter 52.082-
52.108 mm (2.0505- 2.0515 in) Camshaft journal bore inside diameter —
No. 1 55.689-
55.664 mm (2.192- 2.191 in) Camshaft journal bore inside diameter —
No. 2
and No. 3 55.308-
55.283 mm (2.177- 2.176 in) Camshaft journal bore inside diameter —
No. 4 55.684-
55.664 mm (2.192- 2.191 in) Camshaft journal-
to-bearing clearance 0.025-
0.076 mm (0.001- 0.003 in) Runout 0.05 mm (0.002 in) runout of No. 2 or No. 3
relative to No. 1 and No. 4 End play 0.025-
0.150 mm (0.001- 0.006 in) Cylinder Block
Cylinder bore diameter 96.813 mm (3.81 in)
Cylinder bore maximum taper 0.050 mm (0.002 in)
Cylinder bore maximum out-of-
round 0.050 mm (0.002 in)
Main bearing bore inside diameter 68.905 mm (2.713 in)
68.885 mm (2.712 in)
Camshaft bearing bore inside diameter —
intake 47.097 mm (1.8542 in) max. 47.072 mm (1.8532
in) min. Camshaft bearing bore inside diameter —
exhaust 39.739 mm (1.5645 in) max. 39.714 mm (1.5635
in) min. Head gasket surface flatness 0.08 mm (0.003 in) in 152.0 mm (6.00 in)
Crankshaft
Main bearing journal diameter 63.983-
64.003 mm (2.5190- 2.5198 in) Klj . 2 ba
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SPECIFICATIONS
SECTION 303-
01B: Engine — 4.6L (2V) 2003 Mustang Workshop Manual General Specifications
Item Specification
Lubricants and Sealants
Silicone Gasket and Sealant F7AZ-19554-
EA WSE-
M4G323- A4 Premium Engine Coolant VC-
4A,
VC- 5 in Oregon, CXC- 10 in Canada ESE-
M97B44- A Super Premium 5W-
20 Motor Oil XO-5W20-QSP WSS-
M2C153- H Threadlock 262 E2FZ-19554-
B WSK-
M2G351- A6 Metal Surface Cleaner F4AZ-19A536-
RA or
equivalent WSE-
M5B392- A Engine
Displacement 4.6L (2V) (281 CID)
Number of cylinders 8
Bore 90.2 mm (3.55 in)
Stroke 90.0 mm (3.54 in)
Firing order 1-3-7-2-6-5-4-
8 Oil pressure (hot 1,500 rpm) 138-
310 kPa (20- 45 psi) Oil capacity
6.25 ±
0.25 quarts a Compression ratio 9.37:1 (+0.61/-
0.46) Cylinder Head and Valve Train
Combustion chamber volume
43.9 ±
1.5 cm 3 Valve arrangement (front to rear) —
LH b E-I-E-I-E-I-E-I
Valve arrangement (front to rear) —
RH b I-E-I-E-I-E-I-E
Valve guide bore diameter 7.015-
7.044 mm (0.2762- 0.2773 in) Valve stem diameter 6.975-
6.995 mm (0.2754- 0.2746 in) Valve stem-
to-guide clearance — intake 0.020-
0.069 mm (0.00078- 0.00272 in) Valve stem-
to-guide clearance — exhaust 0.046-
0.095 mm (0.0018- 0.0037 in) Valve head diameter —
intake 44.37-
44.63 mm (1.75- 1.76 in) Valve head diameter —
exhaust 35.88-
36.14 mm (1.41- 1.43 in) Valve face runout 0.05 mm (0.002 in)
Valve face angle 45.5 degrees
Valve seat width 1.3-
1.5 mm (0.051- 0.060 in) Valve seat runout (T.I.R.) Recommended 0.025 mm (0.001 in) max. 0.050
mm (0.002 in) Valve seat angle 45 degrees
Valve spring free length (approx.) 51.77-
54.97 mm (2.04- 2.16 in) Valve spring squareness 2 degrees
Valve spring compression pressure 720.0-
800.0 N @ 28.80 mm (161.9 lb @ 1.13 in) Klj . 1 ba
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SPECIFICATIONS
SECTION 303-
01C: Engine — Cobra 4.6L (4V) 2003 Mustang Workshop Manual General Specifications
Item Specification
Lubricants and Sealants
Motorcraft Premium Engine Coolant VC-4-
A
(In Oregon VC- 5, In Canada CXC- 10) ESE-
M97B44- A Motorcraft Premium Gold Engine Coolant VC-7-
A
(In Oregon VC-7- B) WSS-
M97B51- A1 SAE 5W-
20 Engine Premium Synthetic Blend Engine Oil
XO- 5W20- QSP WSS-
M2C153- H Metal Surface Cleaner
F4AZ-
19A536- RA WSE-
M5B392- A Silicone Gasket and Sealant F7AZ-19554-
EA WSE-
M4G323- A4 Pipe Sealant with Teflon® D8AZ-19554-
A WSK-
M2G350- A2 Threadlock 262 E2FZ-19554-
B WSK-
M2G351- A6 Engine
Displacement 4.6L (4V) (281 CID)
Number of cylinders 8
Bore 90.2 mm (3.55 in)
Stroke 90.0 mm (3.54 in)
Firing order 1-3-7-2-6-5-4-
8 Oil pressure 138-310 kPa
Oil capacity
6 ±
0.25 a Compression ratio 8.5:1
Cylinder Head and Valve Train
Cylinder head gasket surface flatness 0.10 mm (0.004 inch) max. overall
Combustion chamber volume 52.6 ±
0.5 cm Valve arrangement (front to rear)
b
Intake (left hand): S-P-S-P-S-P-S-P
Valve arrangement (front to rear)
Exhaust (left hand): E-E-E-E-E-E-E-E
Valve arrangement (front to rear)
Intake (right hand): P-S-P-S-P-S-P-S
Valve arrangement (front to rear)
Exhaust (right hand): E-E-E-E-E-E-E-E
Valve guide bore diameter 7.015-
7.044 mm (0.2762- 0.2773 in) Valve stem diameter—
intake 6.975-
6.995 mm (0.2754- 0.2746 inch) Valve stem diameter—
exhaust 6.949-
6.970 mm (0.2744- 0.2736 inch) Valve stem-
to-guide clearance— intake 0.020-
0.069 mm (0.00078- 0.00272 inch) Valve stem-
to-guide clearance— exhaust 0.046-
0.094 mm (0.0018- 0.0037 in) Valve head diameter—
intake 37 mm (1.46 inch) Klj . 1 ba
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Valve head diameter—
exhaust 30 mm (1.18 inch)
Valve face runout 0.05 mm (0.002 in)
Valve face angle 45.5 degrees
Valve seat width—
intake 1.8-
2.2 mm (0.071- 0.086 inch) Valve seat width—
exhaust 1.8-
2.2 mm (0.071- 0.086 inch) Valve seat runout 0.05 mm (0.002 inch)
Valve seat angle 45 degrees
Valve spring free length—
intake 42.16 mm (1.6598 inch)
Valve spring free length—
exhaust 42.16 mm (1.6598 inch)
Valve spring squareness 2 degrees
Valve spring compression pressure—
intake 711.47 N @ 26.19 mm (159.9 lb-
ft @
1.031 inch) Valve spring compression pressure—
exhaust 711.47 N @ 26.19 mm (159.9 lb-
ft @
1.031 inch) Valve spring installed height 36.14 mm (1.4228 in)
Valve spring installed pressure—
intake 289.1 N @ 36.14 mm (64.99 lb-
ft @
1.4228 inch) Valve spring installed pressure—
exhaust 289.1 N @ 36.14 mm (64.99 lb-
ft @
1.4228 inch) Roller follower ratio 1.8:1
Hydraulic Lash Adjuster
Diameter 16.000-
15.988 mm (0.6299- 0.6294 inch) Clearance-
to-bore 0.018-
0.069 mm (0.000709- 0.002717
inch) Service limit 0.016 mm (1.0006299 inch)
Hydraulic leakdown rate
c 5-
25 seconds Collapsed lash adjuster gap 0.80-
1.20 mm (0.0315- 0.0472 inch) Camshaft
Theoretical valve lift @ 0 lash—
intake (primary and
secondary) 10.0 mm (0.3937 inch)
Theoretical valve lift @ 0 lash—
exhaust 10.0 mm (0.3937 inch)
Lobe lift 5.54 mm (0.218 in)
Allowable lobe lift loss 0.130 mm (0.0051 in)
Journal diameter 26.962-
26.936 mm (1.0615- 1.0605 inch) Camshaft journal bore inside diameter 27.012-
26.987 mm (1.0635- 1.0625 in) Camshaft journal-
to bearing clearance 0.025-
0.076 mm (0.00098- 0.002992
inch) Runout 0.025 mm (0.0010 in)
End play 0.025-
0.165 mm (0.00098- 0.00649 inch) Cylinder Block
Cylinder bore diameter 90.2-
90.239 mm Cylinder bore maximum taper 0.016 mm
Cylinder bore maximum out-of-
round 0.016 mm
Main bearing bore diameter 72.402-
72.422 mm Klj . 2 ba
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Valve Head Diameter
·
Intake 37 mm (1.46 inch)
·
Exhaust 30 mm (1.18 inch)
·
Gauge Diameters 35.0 and 28.0 mm (1.378-
1.102 inch) Valve Face Runout Limit 0.05 mm (0.002 inch)
Valve Face Angle 45.5 degrees
Valve Stem Diameter (Std)
·
Intake 6.975-
6.995 mm (0.2754- 0.2746 inch) ·
Exhaust 6.949-
6.970 mm (0.2744- 0.2736 inch) Valve Springs
·
Compression Pressure (N (Lb) @ Spec
Length) ·
Intake 711.47 N @ 26.19 mm (159.9 Lb-
Ft @ 1.031
inch) ·
Exhaust 711.47 N @ 26.19 mm (159.9 Lb-
Ft @ 1.031
inch) ·
Free Length (Approximate) ·
Intake 42.16 mm (1.6598 inch)
·
Exhaust 42.16 mm (1.6598 inch)
·
Installed Pressure (N (Lb- Ft) @ Spec. Length) ·
Intake 289.1 N @ 36.14 mm (64.99 Lb-
Ft @ 1.4228
inch) ·
Exhaust 289.1 N @ 36.14 mm (64.99 Lb-
Ft @ 1.4228
inch) ·
Service Limit 10% Pressure Loss @ 28.02 mm (1.103 inch)
Roller Follower
·
Ratio 1.8:1
Hydraulic Lash Adjuster
·
Diameter (Std) 16.000-
15.988 mm (0.6299- 0.6294 inch) ·
Clearance to Bore 0.018-
0.069 mm (0.000709- 0.002717 inch) ·
Service Limit 0.016 mm (1.0006299 inch)
·
Hydraulic Leakdown Rate d 5-
25 seconds ·
Collapsed Lash Adjuster Gap— Desired 0.80-
1.20 mm (0.0315- 0.0472 inch) CAMSHAFT
Theoretical Valve Lift @ Zero Lash
·
Intake (Primary) 10.0 mm (0.3937 inch)
·
Intake (Secondary) 10.0 mm (0.3937 inch)
·
Exhaust 10.0 mm (0.3937 inch)
End Play 0.025-
0.165 mm (0.00098- 0.00649 inch) ·
Service Limit 0.190 mm (0.007480 inch)
Journal to Bearing Clearance 0.025-
0.076 mm (0.00098- 0.002992 inch) ·
Service Limit 0.100 mm (0.003937 inch) MAX
Journal Diameter (All) 26.962-
26.936 mm (1.0615- 1.0605 inch) Klj . 2 ba
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DESCRIPTION AND OPERATION
Engine Ignition
The ignition coil (12029), which is mounted on the upper intake manifold, can be described as a coil
pack containing three separate coil units. Each coil unit is individually controlled by the powertrain
control module (PCM) (12A650) through separate wire leads. Each coil unit activates two spark plugs
wired in a series by the spark plug wires (12286).
zOne spark plug activates on the compression stroke and uses the majority of the ignition coil's
stored energy.
z The other spark plug activates on the exhaust stroke and uses very little of the ignition coil's
stored energy.
z Because the pairs of spark plugs are connected in a series, one spark will travel from ground to
the electrode while the other spark will travel from the electrode to ground.
The spark plug (12405):
zchanges the high voltage pulse into a spark which ignites the fuel and air mixture.
z originally equipped on the vehicle has a platinum- enhanced active electrode for long life.
The crankshaft position (CKP) sensor (6C315):
NOTE: Initial engine ignition timing is set at 10 degrees ± 2 degrees before top dead center (BTDC)
and is not adjustable.
zis a variable reluctance sensor triggered by a 36- minus-1 tooth trigger pulse wheel located on
the crankshaft (6303) inside the engine front cover (6019).
The sine wave type signal generated from the crankshaft position sensor provides two types of
information:
zposition of the crankshaft in 10 degree increments
z the crankshaft speed (rpm)
The powertrain control module (PCM) (12A650) uses this information to determine ignition coil turn ON
and turn OFF times and misfire detection.
For additional information, refer to Section 303 - 14 .
SECTION 303-
07A: Engine Ignition — 3.8L 2003 Mustang Workshop Manual Klj . 1 ba
22003 Mustang Workshop Manual
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