2003 FORD MUSTANG pinpoint test b

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
172003 Mustang Workshop Manual
17. 11. 2011file:///C:/Ford/2000 - 2004/tsocache/SHEF_4464/S3B~us~en~ ...

Intake Manifold Vacuum Test
Bring the engine to normal operating temperature. Connect the Vacuum/Pressure Tester to the intake
manifold. Run the engine at the specified idle speed.
The vacuum gauge should read between 51-
74 kPa (15-22 in-Hg) depending upon the engine
condition and the altitude at which the test is performed. Subtract 4.0193 kPa (1 in- Hg) from the
specified reading for every 304.8 m (1,000 feet) of elevation above sea level.
The reading should be steady. If necessary, adjust the gauge damper control (where used) if the
needle is fluttering rapidly. Adjust the damper until the needle moves easily without excessive flutter.
Intake Manifold Vacuum Test—Interpreting Vacuum Gauge Readings
A careful study of the vacuum gauge reading while the engine is idling will help pinpoint trouble areas.
Always conduct other appropriate tests before arriving at a final diagnostic decision. Vacuum gauge
readings, although helpful, must be interpreted carefully.
Most vacuum gauges have a normal band indicated on the gauge face.
The following are potential gauge readings. Some are normal; others should be investigated further.
1. NORMAL READING: Needle between 51- 74 kPa (15-22 in-Hg) and holding steady.
2. NORMAL READING DURING RAPID ACCELERATION AND DECELERATION: When the engine is rapidly accelerated (dotted needle), the needle will drop to a low reading (not to zero).
When the throttle is suddenly released, the needle will snap back up to a higher than normal
figure.
3. NORMAL FOR HIGH- LIFT CAMSHAFT WITH LARGE OVERLAP: The needle will register as low as 51 kPa (15 in - Hg) but will be relatively steady. Some oscillation is normal. Klj . 11 ba
172003 Mustang Workshop Manual
17. 11. 2011file:///C:/Ford/2000 - 2004/tsocache/SHEF_4464/S3B~us~en~ ...

„
If coolant is low, add specified coolant mixture only.
„ If the engine coolant tests too weak, add straight engine coolant until the readings
are within acceptable levels.
„ If the engine coolant tests strong, remove some of the engine coolant and add
water until the readings are within acceptable levels.
5. If the concern remains after the inspection, determine the symptom(s) and GO to Symptom Chart
Symptom Chart
Pinpoint Tests
PINPOINT TEST A: LOSS OF COOLANT
Symptom Chart Condition
Possible Sources Action
z Loss of coolant zRadiator.
z Coolant pump seal.
z Radiator hoses.
z Heater hoses.
z Heater core.
z Engine gaskets.
z Degas bottle or
coolant expansion
tank. z
Go To Pinpoint Test
A .
z The engine overheats zThermostat.
z Coolant pump.
z Internal engine coolant
leak.
z Radiator.
z Cooling fan.
z Pressure relief cap or
radiator cap. z
Go To Pinpoint Test
B .
z The engine does not reach
normal operating temperature z
Thermostat. zGo To Pinpoint Test
C .
Test Step Result / Action to Take
A1 CHECK THE ENGINE COOLANT LEVEL
WARNING: Never remove the pressure relief cap
while the engine is operating or when the cooling system is
hot. Failure to follow these instructions can result in
damage to the cooling system or engine or personal injury.
To avoid having scalding hot coolant or steam blow out of
the degas bottle when removing the pressure relief cap,
wait until the engine is cooled, then wrap a thick cloth
around the pressure relief cap and turn it slowly. Step back Yes
GO to
A2 .
No
REFILL the engine
coolant as necessary.
GO to A2 . Klj . 3 ba
102003 Mustang Workshop Manual
17. 11. 2011file:///C:/Ford/2000 - 2004/tsocache/SHEF_4464/S3B~us~en~ ...

PINPOINT TEST B: THE ENGINE OVERHEATS
Test Step Result / Action to
Take B1 CHECK THE ENGINE COOLANT LEVEL
WARNING: Never remove the pressure relief cap while
the engine is operating or when the cooling system is hot.
Failure to follow these instructions can result in damage to
the cooling system or engine or personal injury. To avoid
having scalding hot coolant or steam blow out of the degas
bottle when removing the pressure relief cap, wait until the
engine is cooled, then wrap a thick cloth around the
pressure relief cap and turn it slowly. Step back while the
pressure is released from the cooling system. When you are
sure all the pressure has been released, turn and remove
the pressure relief cap (still with a cloth). NOTE: If the engine
is hot, allow the engine to cool before proceeding.
z Key in OFF position.
z Check the engine coolant level at the degas bottle/coolant
expansion tank.
z Is the engine coolant OK? Yes
GO to
B2 .
No
REFILL the engine
coolant at the degas
bottle/coolant
expansion tank. Go To Pinpoint Test A .
B2 CHECK THE COOLANT CONDITION
z
Check the coolant for dirt, rust or contamination.
z Is the coolant condition OK? Yes
GO to
B3 .
No
FLUSH the engine
cooling system.
REFER to Engine and Radiator Flushing in
this section. TEST the
system for normal
operation. B3 CHECK FOR AN AIRFLOW OBSTRUCTION
z
Inspect the A/C condenser core and radiator for obstructions
such as leaves or dirt.
z Is there an obstruction? Yes
REMOVE the
obstruction. CLEAN the
A/C condenser core
and radiator. TEST the
system for normal
operation.
No
GO to
B4 .
B4 CHECK THE WATER THERMOSTAT OPERATION
z
Start the engine and allow the engine to run for ten minutes.
z Feel the inlet and outlet heater water hoses and the underside of
the upper radiator hose.
z Are the upper radiator hose and the heater water hoses
cold? Yes
INSTALL a new water
thermostat. REFER to
Thermostat
— 3.8L ,
Thermostat — 4.6L(2V)
or
Thermostat — 4.6L
(4V) in this section.
TEST the system for
normal operation.
No
GO to B5 . Klj . 5 ba
102003 Mustang Workshop Manual
17. 11. 2011file:///C:/Ford/2000 - 2004/tsocache/SHEF_4464/S3B~us~en~ ...

PINPOINT TEST C: THE ENGINE DOES NOT REACH NORMAL
OPERATING TEMPERATURE
Component Tests
Pressure Test —
3.8L
WARNING: Never remove the pressure relief cap while the engine is operating or when the
cooling system is hot. Failure to follow these instructions can result in damage to the cooling
system or engine or personal injury. To avoid having scalding hot coolant or steam blow out of
the degas bottle when removing the pressure relief cap, wait until the engine is cooled, then
wrap a thick cloth around the pressure relief cap and turn it slowly. Step back while the
pressure is released from the cooling system. When you are sure all the pressure has been
released, turn and remove the pressure relief cap (still with a cloth).
1. Remove the radiator cap. Fill the radiator as needed. Fit the pressure tester to the radiator neck, using an aftermarket adapter.
2. CAUTION: Do not pressurize the cooling system beyond 110 kPa (16 psi).
Pump the cooling system to a maximum of 102 kPa (14.9 psi) and hold for 2 minutes. If the
pressure drops within this time, inspect for leaks and repair as necessary. Pressure Test — 4.6L B5 CHECK THE COOLING FAN OPERATION
z
Carry out the cooling fan component tests. Go to Component
Tests.
z Is the cooling fan operation OK? Yes
For diagnosis and
testing of the engine,
REFER to
Section 303 -
00 .
No
INSTALL a new fan
component as
necessary. TEST the
system for normal
operation. Test Step Result / Action to Take
C1 CHECK THE ENGINE
TEMPERATURE z
Start the engine and allow the
engine to idle for ten minutes.
z Feel the inlet and heater water
hoses and the underside of the
upper radiator hose.
z Are the upper radiator hose
and the heater water hoses
cold? Yes
INSTALL a new water thermostat. REFER to
Thermostat
— 3.8L ,
Thermostat — 4.6L(2V) or
Thermostat — 4.6L(4V) in this section. TEST the system
for normal operation.
No
For diagnosis and testing of the engine coolant
temperature gauge, REFER to Section 413 - 01 . Klj . 6 ba
102003 Mustang Workshop Manual
17. 11. 2011file:///C:/Ford/2000 - 2004/tsocache/SHEF_4464/S3B~us~en~ ...

indicates higher water content than required.
„ NOTE: The addition of Motorcraft Cooling System Stop Leak Pellets, VC- 6,
darkens Motorcraft Premium Gold Engine Coolant from yellow to golden tan.
If Motorcraft Premium Gold Engine Coolant (yellow color) VC-7- A or equivalent
meeting Ford specification WSS- M97B51-A1 has a clear or pale yellow color, this
indicates higher water content than required.
„ Dark brown can indicate unauthorized stop leak may have been used. Use
Motorcraft Cooling System Stop Leak Pellets VC- 6 or equivalent meeting Ford
specification ESE-M99B37- 5 except as noted in ES-F65E-19A511- AA only.
„ A light or reddish brown color indicates that rust may be present in the cooling
system. Flush the system and refill with the correct mixture of water and engine
coolant.
„ An iridescent sheen on top of the coolant or a milky brown color can indicate a
trace of oil is entering the system. For additional information on engine diagnosis,
refer to Section 303 - 00 .
3. If the engine coolant appearance is acceptable, test the engine coolant freezing point
range with the special tool. The freezing point should be in the range - 50°F to -10°F. If
the vehicle is driven in cold climates less than - 34°F, it may be necessary to increase the
coolant concentration to get adequate freeze protection.
„Maximum coolant concentration is 60/40.
„ Minimum coolant concentration is 40/60.
4. Check the coolant system conditions:
„If the intercooler fluid is low, add the specified coolant mixture only.
„ If the intercooler coolant fluid tests weak, add straight engine coolant until the
readings are within acceptable levels.
„ If the engine coolant tests strong, remove some of the engine coolant and add
water until readings are within acceptable levels.
5. If the concern remains after the inspection, determine the symptom(s). GO to Symptom Chart .
6. Verify the cooling system is correctly filled and bled. Refer to Supercharger Cooling System Draining, Filling and Bleeding in this section.
Symptom Chart
Pinpoint Tests PINPOINT TEST A: LOSS OF COOLANT SYMPTOM CHART
Condition
Possible Sources Action
z Loss of intercooler
coolant z
Intercooler.
z Intercooler
radiator.
z Water pump.
z Coolant hoses.
z Degas bottle. z
Go To Pinpoint Test A . Klj . 3 ba
72003 Mustang Workshop Manual
18. 11. 2011file:///C:/Ford/2000 - 2004/tsocache/SHEF_4464/S3B~us~en~ ...

Symptom Chart
Pinpoint Tests
PINPOINT TEST A: THE ENGINE DOES NOT CRANK AND THE
RELAY DOES CLICK
SYMPTOM CHART Condition
Possible Sources Action
z The engine does
not crank and the
relay does click z
Battery.
z Fuse.
z Starter
motor/solenoid.
z Ignition switch.
z Circuit. z
Go To Pinpoint Test A .
z The engine does
not crank and the
relay does not
click z
Fuse.
z Battery.
z Starter relay.
z Ignition switch.
z Digital transmission
range (TR) sensor.
z Starter solenoid.
z Clutch pedal
position (CPP)
switch.
z Circuit. z
Go To Pinpoint Test B .
z The engine
cranks slowly z
Battery.
z Starter
motor/solenoid.
z Circuit. z
Go To Pinpoint Test C .
z Unusual starter
noise z
Starter motor
mounting.
z Starter motor.
z Incorrect starter
drive engagement. z
Go To Pinpoint Test D .
z The starter spins
but the engine
does not crank z
Starter Motor zINSPECT the starter motor
mounting and engagement.
REPAIR as necessary.
z Damaged
flywheel/ring gear
teeth. z
INSPECT the flywheel/ring
gear for damaged, missing or
worn teeth. REPAIR as
necessary. Test Step Result / Action to Take
A1 CHECK THE VOLTAGE TO THE STARTER RELAY
z
Measure the voltage between the starter relay pin 30,
circuit 1050 (LG/VT) and ground. Yes
GO to
A2 .
No
REPAIR circuit 1050 (LG/VT) Klj . 2 ba
112003 Mustang Workshop Manual
18. 11. 2011file:///C:/Ford/2000 - 2004/tsocache/SHEF_4464/S3B~us~en~ ...

PINPOINT TEST B: THE ENGINE DOES NOT CRANK AND THE
RELAY DOES NOT CLICK
Test Step Result / Action to Take
B1 CHECK CIRCUIT 33 (WH/PK) FOR VOLTAGE
z
Disconnect: Starter Motor Relay.
z Key in START position.
z Measure the voltage between the starter motor relay pin 85,
circuit 33 (WH/PK) and ground while holding the key in the
START position.
z Is the voltage greater than 10 volts? Yes
GO to
B10 .
No
For automatic
transmissions, GO to
B2 . For manual
transmissions, GO to
B5 .
B2 CHECK CIRCUIT 32 (RD/LB) FOR VOLTAGE AT THE DIGITAL
TR SENSOR z
Key in OFF position.
z Disconnect: Digital TR Sensor C110.
z Key in START position.
z Measure the voltage between the digital TR sensor C110 pin
10, circuit 32 (RD/LB) and ground while holding the key in the
START position.
z Is the voltage greater than 10 volts? Yes
GO to
B3 .
No
GO to B7 .
B3 CHECK CIRCUIT 33 (WH/PK) FOR OPEN
z
Key in OFF position.
z Measure the resistance between the digital TR sensor C110 pin Yes
GO to
B4 .
No
REPAIR circuit 33
(WH/PK). TEST the
system for normal
operation. Klj . 4 ba
112003 Mustang Workshop Manual
18. 11. 2011file:///C:/Ford/2000 - 2004/tsocache/SHEF_4464/S3B~us~en~ ...