1900 MITSUBISHI DIAMANTE coolant level

ENGINEANDENGINEOVERHAUL 3-29
l HOzS sensor l ECT gauge sender l ECT sensor l MAP sensor l IAT sensor l TP sensor l IAC motor l injector harness l ignition coil l CMP sensor l EGR solenoid valve
33. Install the spark plug wires and cover,
34. Replace the O-rings and connect the fuel
lines.
35. Install the air cleaner and intake hose. Con-
nect the breather hose.
36. Fill the cooling system.
37. Connect the negative battery cable
3.01 DDHC Engine
ti See Figures 132 and 133
1. Relieve fuel system pressure. Disconnect the
negative battery cable.
2. Drain the cooling system.
Never open, service or drain the radiator or
cooling system when hot; serious burns can
occur from the steam and hot coolant. Also,
when draining engine coolant, keep in mind
that cats and dogs are attracted to ethylene
glycol antifreeze and could drink any that is
left in an uncovered container or in puddles
on the ground. This will prove fatal in suffi-
cient quantltles. Always drain coolant into a
sealable container. Coolant should be reused
unless it is contaminated or is several years
old.
3. Remove the air intake hoses.
4. Remove air intake plenum and intake mani-
fold.
5. Remove the exhaust manifold.
6. Remove the timing belt. Refer to the timing
belt procedure in this section.
7. Remove the breather hose.
8. Remove the spark plug wire center cover and
remove the spark plug wires.
9. Remove the rocker covers.
10. Remove the intake camshaft sprockets.
11. Remove the rear timing belt cover.
12. Remove the ignition coil assembly.
13. Disconnect all water hoses from the thermo-
stat housing and remove the housing.
14. Disconnect the water inlet from the front
head.
15. Loosen the cylinder head mounting bolts in
the reverse of the torque sequence and loosen the
bolts in three steps. Lift off the cylinder head assem-
bly and remove the head gasket.
To install: 16. Thoroughly clean the sealing surfaces of the
head and block.
17. Place a new head gasket on the cylinder
block with the identification marks in the front top
(upward) position. Do not use sealer on the gasket,
18. Carefully install the cylinder head on the
block. Be sure the head bolt washers are installed
with the chamfered edge upward. Using three even
steps, torque the head bolts in sequence, to 76-83 ft.
Ibs. (105-115 Nm).
@ Timing belt side
7923PG26 :ig. 132 Tighten the cylinder head bolts ac-
:ording to the sequence shown-3.01
SDHC and DDHC) engines
Rear bank
[::od
04
~8 01
Front bank
'1 "8
509 010 011 6
1.03 07 02 7923ffi25 Fig. 133 Rocker cover bolt torque se-
quence-Diamante 3.OL DDHC engine
19. Install new O-ring and connect the water inlet
to the head. Tighten the mounting bolt to 9-11 ft. Ibs
(12-15 Nm).
20. Replace the gaskets and install the thermostat
housing. Tighten the mounting bolts to 12-14 ft. Ibs.
(17-20 Nm).
21. Using new hose clamps, connect the hoses to
the thermostat housing.
22. Install the Ignition coil and torque the mount-
ing bolts to 7 ft. Ibs. (10 Nm).
23. Install the rear timing belt cover and torque
the mounting bolts to 17 ft. Ibs. (24 Nm).
24. Install the intake camshaft sprockets. Tighten
the retaining bolt to 65 ft. Ibs. (90 Nm).
25. Apply sealer to the lower edges of the valve
cover. Tighten the bolts in the proper sequence to
44-51 inch Ibs. (5-6 Nm).
26. Connect the spark plug wires and install the
center cover. Tighten the bolts that secure the center
cover to 27 inch Ibs. (3 Nm)
27. Install the breather hose.
28. Install the timing belt. Refer to the timing belt
procedure in this section,
29. Install the exhaust manifold assembly.
30. Using all new gaskets, install the intake man-
ifold and air intake plenum.
31. Install the air intake hoses.
32. Change the engine oil and oil filter. 33. Fill the system wrth coolant.
34. Connect the negabve battery cable.
35. Adjust the accelerator cable.
36. Start the engine.
37. Check and adjust the idle speed and ignition
timing.
38. Once the vehicle has cooled, recheck the
coolant level.
3.OL SDHC Engine
# See Figure 132
1. Relieve the fuel system pressure.
2. Disconnect the negative battery cable.
3. Drain the cooling system.
Never open, service or drain the radiator or
cooling system when hot; serious burns can
occur from the steam and hot coolant. Also,
when draining engine coolant, keep in mind
that cats and dogs are attracted to ethylene
alvcol antifreeze and could drink any that is
Left in an uncovered container or in puddles
on the ground. This will Drove fatal in suff i-
cient quantities. Always drain coolant into a
sealable container. Coolant should be reused
Unless it is Contaminated or is several years
old.
4. Remove the air intake hose.
5. Remove the exhaust manifold.
6. Remove the air intake plenum and intake
manifold.
7. Remove the timing belt. Refer to the timing
belt procedure in this section.
8. Remove the camshaft sprockets and the rear
timing belt cover.
9. Remove the power steering pump bracket. If
removing the rear head, remove the alternator brace.
10. Disconnect the water inlet pipe.
11. Remove the purge pipe assembly.
12. Remove the valve cover,
13. Using the reverse sequence of the installation
sequence, loosen the cylinder head mounting bolts in
three steps. Lift off the cylmder head assembly and
remove the head gasket.
To install: 14. Thoroughly clean the sealing surfaces of the
head and block.
15. Place a new head gasket on the cylinder
block making sure the identification mark on the
cylrnder head gasket is in the front top (upward) loca-
tion. Do not use sealer on the gasket,
16. Carefully install the cylinder head on the
block. Be sure the head bolt washers are installed
with the chamfered edge upward. Using three even
steps, torque the head bolts in sequence, to 7683 ft.
Ibs. (105-115 Nm).
17. Apply sealer to the lower edges of the half-
round portions and install the valve cover. Tighten
valve cover bolts to 7 ft. Ibs. (9 Nm).
18. Install the purge pipe assembly.
19. Connect the water inlet pipe.
20. Install the power steering pump bracket and
alternator brace.
21. Install the rear timing belt cover and camshaft
sprockets. Torque the retaining bolt to 65 ft. Ibs. (90
Nm).
22. Install the timing belt. Refer to the timing belt
procedure in this section.

.
3-30 ENGINEANDENGINEOVERHAUL
23. Using all new gaskets, install the intake man-
ifold, air intake plenum and exhaust manifold.
24. Install the air intake hose.
25. Fill the system with coolant.
26. Connect the negative battery cable.
27. Start the engine.
28. Check and adjust the idle speed and ignition
timing.
29. Once the vehicle has cooled, recheck the
coolant level.
3.51 Engine
ti See Figure 134
1. Disconnect the negative battery cable.
2. Drain the engine coolant
Never open, service or drain the radiator or
cooling system when hot; serious burns can
occur from the steam and hot coolant. Also,
when draining engine coolant, keep in mind
that cats and dogs are attracted to ethylene
glycol antifreeze and could drink any that is
left in an uncovered container or in puddles
on the ground. This will prove fatal in suffi-
cient quantities. Always drain coolant into a
sealable container. Coolant should be reused
unless it is contaminated or is several years
old.
3. Remove the timing belt. Refer to the timing
belt procedure in this section.
4. Remove the intake and exhaust manifolds.
5. Remove the spark plug wires.
6. Remove the cylrnder head covers.
7. Remove the timing belt rear center cover.
8. Loosen the cylinder head bolts gradually in
three stages, in the opposite of the installation se-
quence.
9. Remove the cylinder head.
To install: 10. Clean the cylinder head and mounting sur-’
face on the engine block.
11. Install the cylinder head using a new gasket.
12. Tighten the bolts in sequence using three
stages to 76-83 ft. Ibs. (103-113 Nm).
13. Install the timing belt rear center cover.
14. Install the cylinder head covers using new
gaskets. Tighten the bolts to 2-3 ft. Ibs. (334 Nm).
15. Install the spark plug wires,
16. Install the intake and exhaust manifolds,
17. Install the timing belt. Refer to the timing belt
procedure in this section.
7923PGD2 Fig. 134 Cylinder head bolt tightening se-
quence-3.5L engine
18. Install any remaining components.
19. Refill the cooling system.
20. Connect the negative battery cable.
REMOVAL &INSTALLATION
1.5L Engine
p See Figure 135
1. Disconnect the negative battery cable.
2. Drain the engine oil.
The EPA warns that prolonged contact with
used engine oil may cause a number of skin
disorders, including cancer! You should
make every effort to minimize your exposure
to used engine oil. Protective gloves should
be worn when changing the oil. Wash your
hands and any other exposed skin areas as
soon as possible after exposure to used en-
gine oil. Soap and water, or waterless hand
cleaner should be used.
3. Remove the bell housing lower cover.
4. Remove the oil pan retainer bolts. Tap the oil
pan with a rubber mallet to break seal.
*Do not use a prytool when removing the oil
pan. If available, oil pan remover tool
MD998727 or equivalent may be used to
break the seal. To install:
5. Clean all gasket surfaces of the cylinder
block and the oil pan.
6. Apply sealant to the gasket surfaces of the oil
pan.
7. Install the oil pan onto the cylinder block
within 15 minutes after applying sealant. Install the
fasteners and tighten to 60 inch Ibs. (7 Nm).
8. Install the bell housing cover.
9. Install the oil drain plug with a new seal and
tighten to 29 ft. Ibs. (40 Nm).
10. Lower the vehicle and fill the crankcase to the
proper level with clean engine oil.
Operating the engine without the proper
amount and type of engine oil will result in
severe engine damage.
11. Connect the negative battery cable. Start the
engine and check for leaks.
1.8L Engine
# See Figure 136
1. Disconnect the negative battery cable.
2. Raise the vehicle and support safely.
3. Remove the oil pan drain plug and drain the
engine oil.
The EPA warns that prolonged contact with
used engine oil may cause a number of skin
disorders, including cancer! You should
make every effort to minimize your exposure
to used engine oil. Protective gloves should
I Fig. 135 Oil pan and related components-Mirage 1.5L (4615) engine

ENGINEANDENGINEOVERHAUL 3-37
1. Ben
2. Power4teerlna Dump 7. washer
8. Crankshaft pullet
9. Damper pulls
10. upper ccwer
11. Lowercowr
12. llmingbeil
13. crsnkshat? E#ocket 14. Flsnge
i 5. Tensbner spacer
16. Tef~kner WkW
1; Tgibnrr
19: camehan sprocket
91251ga
Fig. 155 Exploded view of the timing belt covers, timing belt and related parts-1990-94 1.51
engine
Fig. 156 Camshaft and crankshaft sprocket mark alignment for proper timing belt installa-
tion-1990-94 1.51 engine
Tighten the slot bolt and then the pivot side bolt to
14-20 ft. Ibs. (20-27 Nm).
18. Check the belt tension by holding the ten-
sioner and timing belt together by hand and give the
belt a slight thumb pressure at a point level with ten-
sioner center. Make sure the belt cog crest comes as
deep as about l/4 of the width of the slot side ten-
sioner bolt head. Do not manually overtighten the
belt or it will make a howling noise.
19. Install the timing belt covers and all related
items. 1995-00 MOOFLS
) See Figure 157
1. Disconnect the negative battery cable.
2. Remove the engine undercover.
3. Rotate the crankshaft clockwlse and position
the engine at TDC of the compression stroke.
4. Raise and safely support the weight of the en-
gine using the appropriate equipment. Remove the
A/C clamp, front engine mount bracket and accessory
drive belts.
20. Connect the negative battery cable.
5. Remove the crankshaft pulley. 6. Remove timing belt upper and lower covers.
7. Make a mark on the back of the timing belt
indicating the direction of rotation so it may be re-
assembled in the same direction if it is to be reused.
Loosen the timing belt tensioner and move the ten-
sioner to provide slack to the timing belt. Tighten the
tensioner in this position.
8. Remove the timing belt.
Coolant and engine oil will damage the rub-
ber in the timing belt, drastically reducing its
life. Do not allow engine oil or coolant to
contact the timing belt, the sprockets or ten-
sioner assembly.
9. If defective, remove the tensioner spacer, ten-
sioner spring and tensioner assembly.
To install: 10. Position the tensioner, tensioner spring and
tensioner spacer on engine block.
11. Align the timing marks on the camshaft
sprocket and crankshaft sprocket. This will position
No. 1 piston on TDC on the compression stroke.
12. Position the timing belt on the crankshaft
sprocket and keeping the tension side of the belt
tight, set it on the camshaft sprocket, then the ten-
sioner.
13. Apply slight counterclockwise force to the
camshaft sprocket to give tension to the belt and be
sure all timing marks are aligned.
14. Loosen the pivot side tensioner bolt and the
slot side bolt. Allow the spring to remove the slack.
15. Tighten the slot side tensioner bolt, then the
pivot side bolt. If the pivot side bolt is tightened first,
the tensioner could turn with bolt, causing over ten-
sion.
16. Turn the crankshaft clockwise. Loosen the
pivot side tensioner bolt, then the slot side bolt to al-
low the spring to take up any remaining slack.
Tighten the slot bolt, then the pivot side bolt to 17 ft.
Ibs. (24 Nm).
17. Install the timing belt covers and tighten the
cover bolts to 84-96 inch Ibs. (E-11 Nm). Install all
other applicable components.
liming mark
ming mark
Timing mark
Timing mark
Crankshaft sprocket
79235g5t Fig. 157 Align the timing belt sprockets as
indicated before removing the timing belt-
1995-00 1.51 engine

ENGINEANDENGINEOVERHAUL 3-57
Anything that generates heat and/or friction WIII
eventually burn or wear out (for example, a light bulb
generates heat, therefore its life span is limited). With
this in mind, a running engine generates tremendous
amounts of both; friction is encountered by the mov-
ing and rotating parts inside the engine and heat is
created by friction and combustion of the fuel How-
ever, the engine has systems designed to help reduce
the effects of heat and friction and provide added
longevrty. The oiling system reduces the amount of
friction encountered by the moving parts inside the
engine, while the cooling system reduces heat cre-
ated by friction and combustion If either system is
not maintained, a break-down will be inevitable.
Therefore, you can see how regular maintenance can
affect the service life of your vehicle, If you do not
drain, flush and refill your cooling system at the
proper intervals, deposits WIII begin to accumulate in
the radiator, thereby reducing the amount of heat it
can extract from the coolant The same applies to
your oil and filter; If it is not changed often enough it
becomes laden with contaminates and is unable to
properly lubricate the engine. This increases friction
and wear.
There are a number of methods for evaluating the
condition of your engine. A compression test can re-
veal the condition of your pistons, piston rings,
cylinder bores, head gasket(s), valves and valve
seats. An oil pressure test can warn you of possible
engine bearing, or oil pump failures. Excessrve oil
consumption, evidence of oil in the engine air intake
area and/or bluish smoke from the tailpipe may indi-
cate worn piston rings, worn valve guides and/or
valve seals. As a general rule, an engine that uses no
more than one quart of oil every 1000 miles is in
good condition. Engines that use one quart of oil or
more in less than 1000 miles should first be checked
for oil leaks. If any oil leaks are present, have them
fixed before determining how much oil is consumed
by the engine, especrally if blue smoke is not visible
at the tailpipe
COMPRESSION TEST
# See Figure 226
tccs3801 Fig. 226 A screw-in type compression gauge
is more accurate and easier to use without
an assistant
A noticeable lack of engine power, excessive oil
consumption and/or poor fuel mileage measured
over an extended period are all indicators of internal
engine wear. Worn piston rings, scored or worn
cylinder bores, blown head gaskets, sticking or burnt
valves, and worn valve seats are all possible culprits.
A check of each cylinders compression WIII help lo-
cate the problem.
*A screw-in type compression gauge is
more accurate than the type you simply hold
against the spark plug hole. Although it takes
slightly longer to use, it’s worth the effort to
obtain a more accurate reading.
1 Make sure that the proper amount and vis-
cosity of engine oil is in the crankcase, then ensure
the battery is fully charged.
2. Warm-up the engine to normal operating
temperature, then shut the engine
OFF. 3. Disable the ignition system.
4. Label and disconnect all of the spark plug
wires from the plugs,
5. Thoroughly clean the cylinder head area
around the spark plug ports, then remove the spark
plugs.
6. Set the throttle plate to the fully open (wide-
open throttle) position You can block the accelerator
linkage open for this, or you can have an assistant
fully depress the accelerator pedal.
7. Install a screw-in type compression gauge
into the No. 1 spark plug hole until the fitting is snug.
Be careful not to crossthread the spark plug
hole.
8. According to the tool manufacturers instruc-
tions, connect a remote starting switch to the starting
circuit.
9. With the ignition switch in the
OFF position,
use the remote starting switch to crank the engine
through at least five compression strokes (approxi-
mately 5 seconds of cranking) and record the highest
reading on the gauge
10. Repeat the test on each cylinder, cranking the
engine approximately the same number of compres-
sion strokes and/or time as the first.
11. Compare the hrghest readings from each
cylinder to that of the others. The indicated compres-
sion pressures are considered within specifications if
the lowest reading cylinder is within 75 percent of the
pressure recorded for the highest reading cylinder
For example, if your highest reading cylinder pres-
sure was 150 psi (1034 kPa), then 75 percent of that
would be 113 psi (779 kPa). So the lowest reading
cylinder should be no less than 113 psi (779 kPa).
12. If a cylinder exhibits an unusually low com-
pression reading, pour a tablespoon of clean engine
oil into the cylinder through the spark plug hole and
repeat the compression test. If the compression rises
after adding oil, it means that the cylinder’s piston
rings and/or cylinder bore are damaged or worn, If
the pressure remains low, the valves may not be seat-
ing properly (a valve job is needed), or the head gas-
ket may be blown near that cylinder. If compression in any two adjacent cylinders is low, and if the addi-
tion of oil doesn’t help raise compression, there is
leakage past the head gasket. Oil and coolant in the
combustion chamber, combined with blue or con-
stant white smoke from the tailpipe, are symptoms of
this problem. However, don’t be alarmed by the nor-
mal white smoke emitted from the tailpipe during en-
gine warm-up or from cold weather driving. There
may be evidence of water droplets on the engine dip-
stick and/or oil droplets in the cooling system if a
head gasket is blown.
OIL PRESSURETEST
Check for proper oil pressure at the sending unit
passage with an externally mounted mechanical oil
pressure gauge (as opposed to relying on a factory
Installed dash-mounted gauge). A tachometer may
also be needed, as some specifications may require
running the engine at a specific rpm.
1. With the engine cold, locate and remove the oil
pressure sending unit.
2. Followrng the manufacturers instructions,
connect a mechanical oil pressure gauge and, if nec-
essary, a tachometer to the engine.
3 Start the engine and allow it to idle.
4 Check the oil pressure reading when cold and
record the number. You may need to run the engine
at a specified rpm, so check the specifications,
5. Run the engine until normal operating temper-
ature is reached (upper radiator hose will feel warm)
6. Check the oil pressure reading again with the
engine hot and record the number. Turn the engine
OFF. 7. Compare your hot oil pressure reading to that
given in the chart If the reading is low, check the
cold pressure reading against the chart. If the cold
pressure IS well above the specification, and the hot
reading was lower than the specification, you may
have the wrong viscosity oil in the engine. Change
the oil, making sure to use the proper grade and
quantity, then repeat the test.
Low oil pressure readings could be attributed to
internal component wear, pump related problems, a
low oil level, or oil viscosity that is too low. High oil
pressure readings could be caused by an overfilled
crankcase, too htgh of an oil viscosity or a faulty
pressure relief valve.
Now that you have determined that your engine is
worn out, you must make some decisions. The ques-
tion of whether or not an engine IS worth rebuilding
is largely a subjective matter and one of personal
worth. Is the engine a popular one, or IS it an obso-
lete model? Are parts available? Will it get acceptable
gas mileage once It is rebuilt? Is the car its being put
into worth keeping? Would it be less expensive to
buy a new engine, have your engine rebuilt by a pro,
rebuild it yourself or buy a used engine from a sal-
vage yard? Or would It be simpler and less expensive
to buy another car? If you have considered all these
matters and more, and have still decided to rebuild
the engine, then it is time to decide how you will re-
build it.

ENGINEANDENGINEOVERHAUL 3-69
STARTING THE ENGINE
clearance using the ring and a Now that the engine is installed and every wire and
hose is properly connected, go back and double
check that all coolant and vacuum hoses are con-
, netted. Check that your oil drain plug is installed and
tt tl
C ti
hYs3222 Fig. 271 Most rings are marked to show
which side of the ring should face up when
installed to the piston
J
4. Allow the engine to reach normal operating
?mperature (the upper radiator hose will be hot to
ie touch).
5. At this point you can perform any necessary
hecks or adjustments, such as checking the ignition
ming.
6. Install any remaining components or body
anels which were removed.
IREAKING IT IN
Make the first miles on the new engine, easy ones.
arv the soeed but do not accelerate hard. Most im-
oriantly, do not lug the engine, and avoid sustained
igh speeds until at least 100 miles. Check the en-
ine oil and coolant levels frequently. Expect the en-
ine to use a little oil until the rings seat. Change the
il and filter at 500 miles, 1500 miles, then every

4-10 DRIVEABILITYAND EMISSIONS CONTROLS
I
OPERATION
The Engine Coolant Temperature (ECT) sensor re-
sistance changes in response to engine coolant tem-
perature. The sensor resistance decreases as the
coolant temperature increases, and increases as the
coolant temperature decreases. This provides a refer-
ence signal to the PCM, which indicates engine
coolant temperature. The signal sent to the PCM by
the ECT sensor helps the PCM to determine spark-
advance, EGR flow rate, air/fuel ratio, and engine
temperature. The ECT is a two wire sensor, a 5volt
3. Place the temperature sensing portion of the
sensor into a pan of hot water. Use a thermometer to
monitor the water temperature.
4. Measure the resistance across the sensor ter-
minals while the sensor is in the water. Comoare ob- Fig. 47 Another method of testing the EC1 Fig. 50 Use a deep socket and an extension
is to submerge it in cold or hot water and to reach the ECT sensor. 1 ,
reference signal is sent to the sensor and the signal
return is based upon the change in the measured re-
sistance due to temperature. 1 check resistance
TESTING
ti See Figures 45, 46, 47, and 48
1. Drain the engine coolant to a level below the
intake manifold.
2. Disconnect the sensor wiring harness and re-
move the coolant temperature sensor from the en-
gine.
Fig. 48 The ECT can be monitored with an
tained reading to specifications: ’
93154pos Fig. 45 Unplug the ECT sensor electrical
connector
1 soracross the two sensor pins g3154p30 Fig 48 Test the resistance of the ECT sen-
89574PlO
89574Pll
Fig. 51 . . .
then remove the ECT sensor
from the thermostat housing
a. Water temperature of 32°F (0°C~5.1-6.5
kilo-ohms present
b. Water temperature of 68°F (2O”C)--
2.1-2.7 kilo-ohms present
c. Water temperature of 104°F (4O”C)---
0.9-l .3 kilo-ohms present
d. Water temperature of 176°F (8O”Ck,
0.26-0.36 kilo-ohms present
5. If the resistance differs greatly from standard
value, replace the sensor.
REMOVAL &INSTALLATION
u See Figures 49, 50, 51, and 52
1. Disconnect the negative battery cable. Fig. 52 Before installation, coat the threads
Iolant to a level below the 2. Drain the engine c(
intake manifold.
3. Unplug1 the sensor wiring harness,
4. Unthreac
d and remove the sensor from the en-
gine.
To install:
5. Coat the threads of the sensor with a suitable
sealant and thread into the housing.
6. Tighten the sensor to 22 ft. Ibs. (30 Nm).
7. Refill the cooling system to the proper level.
8. Attach the electrical connector to the sensor
securely. appropriate and Data-stream capable scan 1
1
tnnl
9. Connect the negative battery cable.
Fig. 49 Unplug the ECT sensor electrical
---..^-s-- The Intake Air Temperature (IAT) sensor det
mines the air temnerature enterinn the! intake n er-
- ._ r_ -.-._ _. ._. J . _ ..-. ._
iani- OPERATION
+ See Figure 53

II-6 TROUBLESHOOTING
DIAGhUSTIC PROCEDURES
Gasoline Engines
1. Engine turns over, but wilt not start
a. Check fuel level in fuel tank, add fuel if empty.
b. Check battery condition and state of charge. If voltage and load test below specifica-
tion, charge or replace battery.
c. Check battery terminal and cable condition and tightness. Clean terminals and replace
damaged, worn or corroded cables.
d. Check fuel delivery system. If fuel is not reaching the fuel injectors, check for a loose
electrical connector or defective fuse, relay or fuel pump and replace as necessary.
e. Engine may have excessive wear or mechanical damage such as low cylinder cranking
pressure, a broken camshaft drive system, insufficient valve clearance or bent valves.
f. Check for fuel contamination such as water in the fuel. During winter months, the wa-
ter may freeze and cause a fuel restriction. Adding a fuel additive may help, however
the fuel system may require draining and purging with fresh fuel.
g. Check for ignition system failure. Check for loose or shorted wires or damaged igni-
tion system components. Check the spark plugs for excessive wear or incorrect elec-
trode gap. If the problem is worse in wet weather, check for shorts between the spark
plugs and the ignition coils.
h. Check the engine management system for a failed sensor or control module.
2. Engine does not turn over when attempting to start
a. Check the battery state of charge and condition. If the dash lights are not visible or
very dim when turning the ignition key on, the battery has either failed internally or
discharged, the battery cables are loose, excessively corroded or damaged, or the al-
ternator has failed or internally shorted, discharging the battery. Charge or replacethe
battery, clean or replace the battery cables, and check the alternator output.
b. Check the operation of the neutral safety switch. On automatic transmission vehicles,
try starting the vehicle in both Park and Neutral. On manual transmission vehicles, de-
press the clutch pedal and attempt to start. On some vehicles, these switches can be
adjusted. Make sure the switches or wire connectors are not loose or damaged. Re-
place or adjust the switches as necessary.
c. Check the starter motor, starter solenoid or relay, and starter motor cables and wires.
Check the ground from the engine to the chassis. Make sure the wires are not loose,
damaged, or corroded. If battery voltage is present at the starter relay, try using a re-
mote starter to start the vehicle for test purposes only. Replace any damaged or cor-
roded cables, in addition to replacing any failed components.
d. Check the engine for seizure. If the engine has not been started for a long period of
time, internal parts such as the rings may have rusted to the cylinder walls. The engine
may have suffered internal damage, or could be hydro-locked from ingesting water.
Remove the spark plugs and carefully attempt to rotate the engine using a suitable
breaker bar and socket on the crankshaft pulley. If the engine is resistant to moving, or
moves slightly and then binds, do not force the engine any further before determining
the problem.
3. Enpine stalls immediately when started
a. Check the ignition switch condition and operation. The electrical contacts in the run
position may be worn or damaged. Try restarting the engine with all electrical acces-
sories in the off position. Sometimes turning the key on an off will help in emergency
situations, however once the switch has shown signs of failure, it should be replaced
as soon as possible.
b. Check for loose, corroded, damaged or shorted wires for the ignition system and re-
pair or replace.
c. Check for manifold vacuum leaks or vacuum hose leakage and repair or replace parts
as necessary.
d. Measure the fuel pump delivery volume and pressure. Low fuel pump pressure can
also be noticed as a lack of power when accelerating. Make sure the fuel pump lines
are not restricted. The fuel pump output is not adjustable and requires fuel pump re-
placement to repair.
e. Check the engine fuel and ignition management system. Inspect the sensor wiring and
electrical connectors. A dirty, loose or damaged sensor or control module wire can
simulate a failed component.
f. Check the exhaust system for internal restrictions.
4. Starter motor spins, but does not engage
a. Check the starter motor for a seized or binding pinion gear.
b. Remove the flywheel inspection plate and check for a damaged ring gear.
5. Engine is difficult to start when Gold
a. Check the battery condition, battery state of charge and starter motor current draw. Re-
place the battery if marginal and the starter motor if the current draw is beyond specifi-
cation. b. Check the battery cable condition. Clean the battery terminals and replace corroded or
damaged cables.
c. Check the fuel system for proper operation. A fuel pump with insufficient fuel pressure
or clogged injectors should be replaced.
d. Check the engine’s tune-up status. Note the tune-up specifications and check for items
such as severely worn spark plugs; adjust or replace as needed. On vehicles with
manually adjusted valve clearances, check for tight valves and adjust to specification.
e. Check for a failed coolant temperature sensor, and replace if out of specification.
f. Check the operation of the engine management systems for fuel and ignition; repair or
replace failed components as necessary.
6. En#ine is ditticutt to start when hot
a. Check the air filter and air intake system. Replace the air filter if it is dirty or contami-
nated. Check the fresh air intake system for restrictions or blockage.
b. Check for loose or deteriorated engine grounds and clean, tighten or replace as
needed.
c. Check for needed maintenance. Inspect tune-up and service related items such as
spark plugs and engine oil condition, and check the operation of the engine fuel and
ignition management system.
Diesel Engines
1. Engine turns over but won’t start
a. Check engine starting procedure and restart engine.
b. Check the glow plug operation and repair or replace as necessary.
c. Check for air in the fuel system or fuel filter and bleed the air as necessary.
d. Check the fuel delivery system and repair or replace as necessary.
e. Check fuel level and add fuel as needed.
f. Check fuel quality. If the fuel is contaminated, drain and flush the fuel tank.
g. Check engine compression. If compression is below specification, the engine may
need to be renewed or replaced.
h. Check the injection pump timing and set to specification.
i. Check the injection pump condition and replace as necessary.
j. Check the fuel nozzle operation and condition or replace as necessary.
2. Engine does
hot turn over when attempting to start
a. Check the battery state of charge and condition. If the dash lights are not visible or
very dim when turning the ignition key on, the battery has either failed internally or
discharged, the battery cables are loose, excessively corroded or damaged, or the al-
ternator has failed or internally shorted, discharging the battery. Charge or replace the
battery, clean or replace the battery cables, and check the alternator output.
b. Check the operation of the neutral safety switch. On automatic transmission vehicles,
try starting the vehicle in both Park and Neutral. On manual transmission vehicles, de-
press the clutch pedal and attempt to start. On some vehicles, these switches can be
adjusted. Make sure the switches or wire connectors are not loose or damaged. Re-
place or adjust the switches as necessary.
c. Check the starter motor, starter solenoid or relay, and starter motor cables and wires.
Check the ground from the engine to the chassis. Make sure the wires are not loose,
damaged, or corroded. If battery voltage is present at the starter relay, try using a re-
mote starter to start the vehicle for test purposes only. Replace any damaged or cor-
roded cables, in addition to replacing any failed components.
d. Check the engine for seizure. If the engine has not been started for a long period of
time, internal parts such as the rings may have rusted to the cylinder walls. The engine
may have suffered internal damage, or could be hydro-locked from ingesting water.
Remove the injectors and carefully attempt to rotate the engine using a suitable
breaker bar and socket on the crankshaft pulley. If the engine is resistant to moving, or
moves slightly and then binds, do not force the engine any further before determining
the cause of the problem.
3. Engine stalls afier starting
a. Check for a restriction in the fuel return line or the return line check valve and repair as
necessary.
b. Check the glow plug operation for turning the glow plugs off too soon and repair as
necessary.
c. Check for incorrect injection pump timing and reset to specification.
d. Test the engine fuel pump and replace if the output is below specification.
e. Check for contaminated or incorrect fuel. Completely flush the fuel system and replace
with fresh fuel.
f. Test the engine’s compression for low compression. If below specification, mechanical
repairs are necessary to repair.
g. Check for air in the fuel. Check fuel tank fuel and fill as needed.
h. Check for a failed injection pump. Replace the pump, making sure to properly set the
pump timing.

11-8 TROUBLESHOOTING
Ignition systems may be controlled by, or linked to, the engine fuel management sys-
tem. Similar to the fuel injection system, these ignition systems rely on electronic sen-
sors for information to determine the optimum ignition timing for a given engine speed
and load. Some ignition systems no longer allow the ignition timing to be adjusted.
Feedback from low voltage electrical sensors provide information to the control unit to
determine the amount of ignition advance. On these systems, if a failure occurs the failed
component must be replaced. Before replacing suspected failed electrical components,
carefully inspect the wiring and electrical connectors to the related components. Make
sure the electrical connectors are fully connected, clean and not physically damaged. If
necessary, clean the electrical contacts using electrical contact cleaner. The use of clean-
ing agents not specifically designed for electrical contacts should be avoided, as they
could leave a surface film or damage the insulation of the wiring.
1. Engine makes a knocking or pinging noise when accelerating
a. Check the octane rating of the fuel being used. Depending on the type of driving or
driving conditions, it may be necessary to use a higher octane fuel.
b. Verify the ignition system settings and operation. Improperly adjusted ignition timing
or a failed component, such as a knock sensor, may cause the ignition timing to ad-
vance excessively or prematurely. Check the ignition system operation and adjust, or
replace components as needed.
c. Check the spark plug gap, heat range and condition. If the vehicle is operated in se-
vere operating conditions or at continuous high speeds, use a colder heat range spark
plug. Adjust the spark plug gap to the manufacturer’s recommended specification and
replace worn or damaged spark plugs.
2. Sfarter motor grinds when used
a. Examine the starter pinion gear and the engine ring gear for damage, and replace dam-
aged parts.
b. Check the starter mounting bolts and housing. If the housing is cracked or damaged
replace the starter motor and check the mounting bolts for tightness.
3. Engine makes a screeching noise
a. Check the accessory drive belts for looseness and adjust as necessary.
b. Check the accessory drive belt tensioners for seizing or excessive bearing noises and
replace if loose, binding, or excessively noisy.
c. Check for a seizing water pump. The pump may not be leaking; however, the bearing
may be faulty or the impeller loose and jammed. Replace the water pump.
4. Engine makes a growling noise
a. Check for a loose or failing water pump. Replace the pump and engine coolant.
b. Check the accessory drive belt tensioners for excessive bearing noises and replace if
loose or excessively noisy.
5. Engine makes a ticking or tapping noise
a. On vehicles with hydraulic lash adjusters, check for low or dirty engine oil and top off
or replace the engine oil and filter.
b. On vehicles with hydraulic lash adjusters, check for collapsed lifters and replace failed
components.
c. On vehicles with hydraulic lash adjusters, check for low oil pressure caused by a re-
stricted oil filter, worn engine oil pump, or oil pressure relief valve.
d. On vehicles with manually adjusted valves, check for excessive valve clearance or
worn valve train parts. Adjust the valves to specification or replace worn and defective
parts.
e. Check for a loose or improperly tensioned timing belt or timing chain and adjust or re-
place parts as necessary.
f. Check for a bent or sticking exhaust or intake valve. Remove the engine cylinder head
to access and replace.
6. Engine makes a heavy knocking noise
a. Check for a loose crankshaft pulley or flywheel; replace and torque the mounting
bolt(s) to specification.
b. Check for a bent connecting rod caused by a hydro-lock condition. Engine disassem-
bly is necessary to inspect for damaged and needed replacement parts.
c. Check for excessive engine rod bearing wear or damage. This condition is also asso-
ciated with low engine oil pressure and will require engine disassembly to inspect for
damaged and needed replacement parts,
7. Vehicle has a fuel odor when driven ’ a. Check the fuel gauge level. If the fuel gauge registers full, it is possible that the odor is
caused by being filled beyond capacity, or some spillage occurred during refueling.
The odor should clear after driving an hour, or twenty miles, allowing the vapor canis-
ter to purge.
b. Check the fuel filler cap for looseness or seepage. Check the cap tightness and, if
loose, properly secure. If seepage is noted, replace the filler cap.
c. Check for loose hose clamps, cracked or damaged fuel delivery and return lines, or
leaking components or seals, and replace or repair as necessary. d. Check the vehicle’s fuel economy. If fuel consumption has increased due to a failed
component, or if the fuel is not properly ignited due to an ignition related failure, the
catalytic converter may become contaminated. This condition may also trigger the
check engine warning light. Check the spark plugs for a dark, rich condition or verify
the condition by testing the vehicle’s emissions. Replace fuel fouled spark plugs, and
test and replace failed components as necessary.
5. Vehicle has a rotten egg odor when driven
a. Check for a leaking intake gasket or vacuum leak causing a lean running condition. A
lean mixture may result in increased exhaust temperatures, causing the catalytic con-
verter to run hotter than normal. This condition may also trigger the check engine
warning light. Check and repair the vacuum leaks as necessary.
b. Check the vehicle’s alternator and battery condition. If the alternator is overcharging,
the battery electrolyte can be boiled from the battery, and the battery casing may begin
to crack, swell or bulge, damaging or shorting the battery internally. If this has oc-
curred, neutralize the battery mounting area with a suitable baking soda and water
mixture or equivalent, and replace the alternator or voltage regulator. Inspect, service,
and load test the battery, and replace if necessary.
9. Vehicle has a sweet odor when driven
a. Check for an engine coolant leak caused by a seeping radiator cap, loose hose clamp,
weeping cooling system seal, gasket or cooling system hose and replace or repair as
needed.
b. Check for a coolant leak from the radiator, coolant reservoir, heater control valve or
under the dashboard from the heater core, and replace the failed part as necessary.
c. Check the engine’s exhaust for white smoke in addition to a sweet odor. The presence
of white, steamy smoke with a sweet odor indicates coolant leaking into the combus-
tion chamber. Possible causes include a failed head gasket, cracked engine block or
cylinder head. Other symptoms of this condition include a white paste build-up on the
inside of the oil filler cap, and softened, deformed or bulging radiator hoses.
19. Engine vibraies when idling
a. Check for loose, collapsed, or damaged engine or transmission mounts and repair or
replace as necessary.
b. Check for loose or damaged engine covers or shields and secure or replace as neces-
sary.
11. Engine vibrates during acceleration
a. Check for missing, loose or damaged exhaust system hangers and mounts; replace or
repair as necessary.
b. Check the exhaust system routing and fit for adequate clearance or potential rubbing;
repair or adjust as necessary.
7. Battery goes dead while driving
a. Check the battery condition. Replace the battery if the battery will not hold a charge or
fails a battery load test. If the battery loses fluid while driving, check for an overcharg-
ing condition. If the alternator is overcharging, replace the alternator or voltage regula-
tor. (A voltage regulator is typically built into the alternator, necessitating alternator re-
placement or overhaul.)
b. Check the battery cable condition. Clean or replace corroded cables and clean the bat-
tery terminals.
c. Check the alternator and voltage regulator operation. If the charging system is over or
undercharging, replace the alternator or voltage regulator, or both.
d. Inspect the wiring and wire connectors at the alternator for looseness, a missing .
ground or defective terminal, and repair as necessary.
e. Inspect the alternator drive belt tension, tensioners and condition. Properly tension the
drive belt, replace weak or broken tensioners, and replace the drive belt if worn or
cracked.
2. Battery goes dead overnight
a. Check the battery condition. Replace the battery if the battery will not hold a charge or
fails a battery load test.
b. Check for a voltage draw, such as a trunk light, interior light or glove box light staying
on. Check light switch position and operation, and replace if defective.
c. Check the alternator for an internally failed diode, and replace the alternator if defec-
tive.
1. Engine overheats
a. Check the coolant level. Set the heater temperature to full hot and check for internal air
pockets, bleed the cooling system and inspect for leakage. Top off the cooling system
with the correct coolant mixture.
b. Pressure test the cooling system and radiator cap for leaks. Check for seepage caused
by loose hose clamps, failed coolant hoses, and cooling system components such as
the heater control valve, heater core, radiator, radiator cap, and water pump. Replace
defective parts and fill the cooling system with the recommended coolant mixture.