engine oil CHRYSLER VOYAGER 1996 Owners Manual

(5) Test resistance of spark plug cables. Refer to
Group 8D, Ignition System.
(6) Test ignition coils primary and secondary resis-
tance. Replace parts as necessary. Refer to Group 8D,
Ignition System.
(7) Check fuel pump pressure at idle and different
RPM ranges. Refer to Group 14, Fuel System for
Specifications.
(8) The air filter elements should be replaced as
specified in Group 0, Lubrication and Maintenance.
(9) Inspect crankcase ventilation system as out-
lined in Group 25, Emission Control Systems.
(10) Road test vehicle as a final test.
HONING CYLINDER BORES
(1) Used carefully, the cylinder bore resizing hone
C-823 equipped with 220 grit stones, is the best tool
for this job. In addition to deglazing, it will reduce
taper and out-of-round as well as removing light
scuffing, scoring or scratches. Usually a few strokes
will clean up a bore and maintain the required lim-
its.
(2) Deglazing of the cylinder walls may be done
using a cylinder surfacing hone, Tool C-3501,
equipped with 280 grit stones, if the cylinder bore is
straight and round. 20-60 strokes depending on the
bore condition, will be sufficient to provide a satisfac-
tory surface. Inspect cylinder walls after each 20
strokes, using a light honing oil.Do not use engine
or transmission oil, mineral spirits or kerosene.
(3) Honing should be done by moving the hone up
and down fast enough to get a cross-hatch pattern.
When hone marksintersectat 50-60 degrees, the
cross hatch angle is most satisfactory for proper seat-
ing of rings (Fig. 2).(4) A controlled hone motor speed between
200-300 RPM is necessary to obtain the proper cross-
hatch angle. The number of up and down strokes per
minute can be regulated to get the desired 50-60
degree angle. Faster up and down strokes increase
the cross-hatch angle.
(5) After honing, it is necessary that the block be
cleaned again to remove all traces of abrasive.
CAUTION: Ensure all abrasives are removed from
engine parts after honing. It is recommended that a
solution of soap and hot water be used with a
brush and the parts then thoroughly dried. The bore
can be considered clean when it can be wiped
clean with a white cloth and cloth remains clean.
Oil the bores after cleaning to prevent rusting.
MEASURING MAIN BEARING AND CONNECTING
ROD BEARING CLEARANCES
PLASTIGAGE METHOD
Engine crankshaft bearing clearances can be deter-
mined by use of Plastigage or equivalent. The follow-
ing is the recommended procedure for the use of
Plastigage:
NOTE: The total clearance of the main bearings
can only be determined by removing the weight of
the crankshaft. This can be accomplished by either
of two methods:
PREFERRED METHOD
Shimming the bearings adjacent to the bearing to
be checked in order to remove the clearance between
upper bearing shell and the crankshaft. This can be
accomplished by placing a minimum of 0.254 mm
(0.010 in.) shim (e. g. cardboard, matchbook cover,
etc.) between the bearing shell and the bearing cap
on the adjacent bearings and tightening bolts to
14-20 N´m (10-15 ft. lbs.). The number of main bear-
ing will vary from engine to engine.
Fig. 2 Cylinder Bore Cross-Hatch Pattern
Fig. 3 Plastigage Placed in Lower Shell
NSENGINE 9 - 3
GENERAL INFORMATION (Continued)

ENGINE WITH 5 MAIN BEARINGS
²When checking #1 main bearing shim #2 main
bearing.
²When checking #2 main bearing shim #1 & 3
main bearing.
²When checking #3 main bearing shim #2 & 4
main bearing.
²When checking #4 main bearing shim #3 & 5
main bearing.
²When checking #5 main bearing shim #4 main
bearing.
ENGINE WITH 4 MAIN BEARING
²When checking #1 main bearing shim # 2 main
bearing.
²When checking #2 main bearing shim #1 & #3
main bearing.
²When checking #3 main bearing shim #2 & #4
main bearing.
²When checking #4 main bearing shim #3 main
bearing.
NOTE: REMOVE ALL SHIMS BEFORE REASSEM-
BLING ENGINE
ALTERNATIVE METHOD
The weight of the crankshaft can be supported by a
jack under the counterweight adjacent to the bearing
being checked.
PLASTIGAGE PROCEDURE
(1) Remove oil film from surface to be checked.
Plastigage is soluble in oil.
(2) Place a piece of Plastigage across the entire
width of the bearing shell in the cap approximately
6.35 mm (1/4 in.) off center and away from the oil
holes (Fig. 3). (In addition, suspected areas can be
checked by placing the Plastigage in the suspected
area). Torque the bearing cap bolts of the bearing
being checked to the proper specifications.
(3) Remove the bearing cap and compare the
width of the flattened Plastigage (Fig. 4) with the
metric scale provided on the package. Locate the
band closest to the same width. This band shows theamount of clearance in thousandths of a millimeter.
Differences in readings between the ends indicate the
amount of taper present. Record all readings taken.
Refer to Engine Specifications.Plastigage gener-
ally is accompanied by two scales. One scale is
in inches, the other is a metric scale.
NOTE: Plastigage is available in a variety of clear-
ance ranges. Use the most appropriate range for
the specifications you are checking.
CONNECTING ROD BEARING CLEARANCE
Engine connecting rod bearing clearances can be
determined by use of Plastigage or equivalent. The
following is the recommended procedure for the use
of Plastigage:
(1) Rotate the crankshaft until the connecting rod
to be checked is at the bottom of its stroke.
(2) Remove oil film from surface to be checked.
Plastigage is soluble in oil.
(3) Place a piece of Plastigage across the entire
width of the bearing shell in the bearing cap approx-
imately 6.35 mm (1/4 in.) off center and away from
the oil hole (Fig. 3). In addition, suspect areas can be
checked by placing plastigage in the suspect area.
(4) Assemble the rod cap with Plastigage in place.
Tighten the rod cap to the specified torque.Do not
rotate the crankshaft while assembling the cap
or the Plastigage may be smeared, giving inac-
curate results.
(5) Remove the bearing cap and compare the
width of the flattened Plastigage (Fig. 4) with the
scale provided on the package. Locate the band clos-
est to the same width. This band indicates the
amount of oil clearance. Differences in readings
between the ends indicate the amount of taper
present. Record all readings taken. Refer to Engine
Specifications.Plastigage generally is accompa-
nied by two scales. One scale is in inches, the
other is a metric scale. If the bearing clearance
exceeds 0.076 mm (0.003 in.) replace bearing.
NOTE: Plastigage is available in a variety of clear-
ance ranges. Use the most appropriate range for
the specifications you are checking.
REPAIR OF DAMAGED OR WORN THREADS
Damaged or worn threads (including aluminum
head spark plug threads) can be repaired. Essen-
tially, this repair consists of drilling out worn or
damaged threads, tapping the hole with a special
Heli-Coil Tap, (or equivalent) and installing an insert
into the tapped hole. This brings the hole back to its
original thread size.
Fig. 4 Clearance Measurement
9 - 4 ENGINENS
GENERAL INFORMATION (Continued)

CAUTION: Be sure that the tapped holes maintain
the original centerline.
Heli-Coil tools and inserts are readily available
from automotive parts jobbers.
HYDROSTATIC LOCKED ENGINE
When an engine is suspected to be hydrostatically
locked, regardless of what caused the problem, these
steps should be used.
CAUTION: Do Not Use Starter Motor To Rotate
Engine, severe damage may occur.
(1) Inspect air cleaner, induction system and
intake manifold to insure system is dry and clear of
foreign material.
(2) Remove negative battery cable.
(3) Place a shop towel around the spark plugs
when removing them from the engine. This will catch
any fluid that may possibly be in the cylinder under
pressure.
(4) With all spark plugs removed, rotate engine
crankshaft using a breaker bar and socket.
(5) Identify the fluid in the cylinder(s) (i.e., cool-
ant, fuel, oil or other).
(6) Make sure all fluid has been removed from the
cylinders. Inspect engine for damage (i.e., Connecting
Rods, Pistons, Valves etc.)
(7) Repair engine or components as necessary to
prevent this problem from occurring again.
CAUTION: Squirt approximately 1 teaspoon of oil
into cylinders, rotate engine to lubricate the cylin-
der walls to prevent damage on restart.
(8) Install new spark plugs.
(9) Drain engine oil and remove oil filter.
(10) Fill engine with specified amount of approved
oil and install new oil filter.
(11) Connect negative battery cable.
(12) Start engine and check for any leaks.
ENGINE OIL
Checking Oil Level
To assure proper engine lubrication, the engine oil
must be maintained at the correct level. Check the
oil level at regular intervals, such as every fuel stop.
The best time to check the oil level is about 5 min-
utes after a fully warmed-up engine is shut off, or
before starting the vehicle after it has sat overnight.
Checking the oil while the vehicle is on level
ground, will improve the accuracy of the oil level
readings. For 2.4L, 3.3L and 3.8L engines, maintain
the oil level between the MIN and MAX markings on
the dipstick. Adding one quart of oil when the read-ing is at the MIN mark will result in a MAX reading
on these engines. For the 3.0L engine, add one full
quart when the level on the dipstick is at or below
the ADD mark.
ENGINE OIL SERVICE
WARNING: NEW OR USED ENGINE OIL CAN BE
IRRITATING TO THE SKIN. AVOID PROLONGED OR
REPEATED SKIN CONTACT WITH ENGINE OIL.
CONTAMINANTS IN USED ENGINE OIL, CAUSED BY
INTERNAL COMBUSTION, CAN BE HAZARDOUS TO
YOUR HEALTH. THOROUGHLY WASH EXPOSED
SKIN WITH SOAP AND WATER. DO NOT WASH
SKIN WITH GASOLINE, DIESEL FUEL, THINNER, OR
SOLVENTS, HEALTH PROBLEMS CAN RESULT. DO
NOT POLLUTE, DISPOSE OF USED ENGINE OIL
PROPERLY. CONTACT YOUR DEALER OR GOVERN-
MENT AGENCY FOR LOCATION OF COLLECTION
CENTER IN YOUR AREA.
ENGINE OIL SPECIFICATION
CAUTION: Do not use non-detergent or straight
mineral oil when adding or changing crankcase
lubricant. Engine failure can result.
NSENGINE 9 - 5
GENERAL INFORMATION (Continued)

API SERVICE GRADE CERTIFIED
Use an engine oil that is API Service Grade Certi-
fied. MOPARtprovides engine oils that conforms to
this service grade.
SAE VISCOSITY
An SAE viscosity grade is used to specify the vis-
cosity of engine oil. Use only, engine oils with multi-
ple viscosities such as 5W-30 or 10W-30. These are
specified with a dual SAE viscosity grade which indi-
cates the cold-to-hot temperature viscosity range.
Select an engine oil that is best suited to your par-
ticular temperature range and variation (Fig. 5).
ENERGY CONSERVING OIL
An Energy Conserving type oil is recommended for
gasoline engines. They are designated as either
ENERGY CONSERVING or ENERGY CONSERV-
ING II.
CONTAINER IDENTIFICATION
Standard engine oil identification notations have
been adopted to aid in the proper selection of engine
oil. The identifying notations are located on the label
of engine oil plastic bottles and the top of engine oil
cans (Fig. 6).
ENGINE OIL CHANGE
Change engine oil at mileage and time intervals
described in the Maintenance Schedule.
TO CHANGE ENGINE OIL
Run engine until achieving normal operating tem-
perature.
(1) Position the vehicle on a level surface and turn
engine off.
(2) Hoist and support vehicle on safety stands.
Refer to Hoisting and Jacking Recommendations.
(3) Remove oil fill cap.
(4) Place a suitable drain pan under crankcase
drain.
(5) Remove drain plug from crankcase and allow
oil to drain into pan. Inspect drain plug threads for
stretching or other damage. Replace drain plug and
gasket if damaged.
(6) Install drain plug in crankcase.
(7) Lower vehicle and fill crankcase with specified
type and amount of engine oil described in this sec-
tion.
(8) Install oil fill cap.
(9) Start engine and inspect for leaks.
(10) Stop engine and inspect oil level.
Fig. 5 Temperature/Engine Oil Viscosity
Fig. 6 Engine Oil Container Standard Notations
9 - 6 ENGINENS
GENERAL INFORMATION (Continued)

ENGINE DIAGNOSIS
INDEX
page page
DIAGNOSIS AND TESTING
CYLINDER COMBUSTION
PRESSURE LEAKAGE TEST.............. 8
CYLINDER COMPRESSION PRESSURE TEST . . 7
ENGINE DIAGNOSISÐMECHANICAL......... 12
ENGINE DIAGNOSISÐPERFORMANCE...... 10GENERAL INFORMATION.................. 7
INSPECTION
(ENGINE OIL LEAKS IN GENERAL)......... 8
INTAKE MANIFOLD LEAKAGE DIAGNOSIS..... 7
LASH ADJUSTER (TAPPET)
NOISE DIAGNOSIS...................... 8
DIAGNOSIS AND TESTING
GENERAL INFORMATION
Engine diagnosis is helpful in determining the
causes of malfunctions.
These malfunctions may be classified as either
mechanical (e.g., a strange noise), or performance
(e.g., engine idles rough and stalls).
Refer to the Service DiagnosisÐMechanical Chart
and the Service DiagnosisÐPerformance Chart, for
possible causes and corrections of malfunctions. Refer
to Group 14, Fuel System, for the fuel system diag-
nosis.
Additional tests and diagnostic procedures may be
necessary for specific engine malfunctions that can-
not be isolated with the Service Diagnosis charts.
Information concerning additional tests and diagno-
sis is provided within the following:
²Cylinder Compression Pressure Test
²Cylinder Combustion Pressure Leakage Test
²Engine Cylinder Head Gasket Failure Diagnosis
²Intake Manifold Leakage Diagnosis
INTAKE MANIFOLD LEAKAGE DIAGNOSIS
An intake manifold air leak is characterized by
lower than normal manifold vacuum. Also, one or
more cylinders may not be functioning.
WARNING: USE EXTREME CAUTION WHEN THE
ENGINE IS OPERATING. DO NOT STAND IN A
DIRECT LINE WITH THE FAN. DO NOT PUT YOUR
HANDS NEAR THE PULLEYS, BELTS OR THE FAN.
DO NOT WEAR LOOSE CLOTHING.
(1) Start the engine.
(2) Spray a small stream of water (Spray Bottle) at
the suspected leak area.
(3) If a change in RPM'S, the area of the suspected
leak has been found.
(4) Repair as required.
CYLINDER COMPRESSION PRESSURE TEST
The results of a cylinder compression pressure test
can be utilized to diagnose several engine malfunc-
tions.
Ensure the battery is completely charged and the
engine starter motor is in good operating condition.
Otherwise the indicated compression pressures may
not be valid for diagnosis purposes.
(1) Check engine oil level and add oil if necessary.
(2) Drive the vehicle until engine reaches normal
operating temperature. Select a route free from traf-
fic and other forms of congestion, observe all traffic
laws, and accelerate through the gears several times
briskly.
(3) Remove all spark plugs from engine. As spark
plugs are being removed, check electrodes for abnor-
mal firing indicators fouled, hot, oily, etc. Record cyl-
inder number of spark plug for future reference.
(4) Disconnect coil wire from distributor and
secure to good ground to prevent a spark from start-
ing a fire (Conventional Ignition System). For Direct
Ignition System DIS disconnect the coil connector.
(5) Be sure throttle blade is fully open during the
compression check.
(6) Insert compression gage adaptor into the #1
spark plug hole in cylinder head. Crank engine until
maximum pressure is reached on gage. Record this
pressure as #1 cylinder pressure.
(7) Repeat the previous step for all remaining cyl-
inders.
(8) Compression should not be less than (689kPa)
100 psi and not vary more than 25 percent from cyl-
inder to cylinder.
(9) If one or more cylinders have abnormally low
compression pressures, repeat the compression test.
(10) If the same cylinder or cylinders repeat an
abnormally low reading on the second compression
test, it could indicate the existence of a problem in
the cylinder in question.The recommended com-
pression pressures are to be used only as a
guide to diagnosing engine problems. An engine
should not be disassembled to determine the
NSENGINE 9 - 7

cause of low compression unless some malfunc-
tion is present.
(11) Clean or replace spark plugs as necessary
and adjust gap as specified in Group 8, Electrical.
Tighten to specifications.
(12) Test resistance of spark plug cables. Refer to
Group 8, Electrical Ignition System Secondary Cir-
cuit Inspection.
(13) Test coil output voltage, primary and second-
ary resistance. Replace parts as necessary. Refer to
Group 8, Electrical Ignition System.
(14) Check fuel pump pressure at idle and differ-
ent RPM ranges. Refer to Group 14, Fuel System for
Specifications.
(15) The air filter elements should be replaced as
specified in Group 0, Lubrication and Maintenance,.
(16) Inspect crankcase ventilation system as out
lined in Group 0, Lubrication and Maintenance. For
emission controls see Group 25, Emission Controls
for service procedures.
(17) Inspect and adjust accessory belt drives refer-
ring to Group 7, Cooling System, Accessory Drive
Belts for proper adjustments.
(18) Road test vehicle as a final test.
CYLINDER COMBUSTION PRESSURE LEAKAGE
TEST
The combustion pressure leakage test provides an
accurate means for determining engine condition.
Combustion pressure leakage testing will detect:
²Exhaust and intake valve leaks (improper seat-
ing).
²Leaks between adjacent cylinders or into water
jacket.
²Any causes for combustion/compression pressure
loss.
WARNING: DO NOT REMOVE THE RADIATOR CAP
WITH THE SYSTEM HOT AND UNDER PRESSURE
BECAUSE SERIOUS BURNS FROM COOLANT CAN
OCCUR.
Check the coolant level and fill as required. DO
NOT install the radiator cap.
Start and operate the engine until it attains nor-
mal operating temperature, then turn the engine
OFF.
Clean spark plug recesses with compressed air.
Remove the spark plugs.
Remove the oil filler cap.
Remove the air cleaner.
Calibrate the tester according to the manufactur-
er's instructions. The shop air source for testing
should maintain 483 kPa (70 psi) minimum, 1 379
kPa (200 psi) maximum and 552 kPa (80 psi) recom-
mended.Perform the test procedures on each cylinder
according to the tester manufacturer's instructions.
While testing, listen for pressurized air escaping
through the throttle body, tailpipe and oil filler cap
opening. Check for bubbles in the radiator coolant.
All gauge pressure indications should be equal,
with no more than 25% leakage.
FOR EXAMPLE:At 552 kPa (80 psi) input pres-
sure, a minimum of 414 kPa (60 psi) should be main-
tained in the cylinder.
LASH ADJUSTER (TAPPET) NOISE DIAGNOSIS
A tappet-like noise may be produced from several
items. Check the following items.
(1) Engine oil level too high or too low. This may
cause aerated oil to enter the adjusters and cause
them to be spongy.
(2) Insufficient running time after rebuilding cylin-
der head. Low speed running up to 1 hour may be
required.
(3) During this time, turn engine off and let set for
a few minutes before restarting. Repeat this several
times after engine has reached normal operating
temperature.
(4) Low oil pressure.
(5) The oil restrictor pressed into the vertical oil
passage to the cylinder head is plugged with debris.
(6) Air ingested into oil due to broken or cracked
oil pump pick up.
(7) Worn valve guides.
(8) Rocker arm ears contacting valve spring
retainer.
(9) Rocker arm loose, adjuster stuck or at maxi-
mum extension and still leaves lash in the system.
(10) Faulty lash adjuster.
a. Check lash adjusters for sponginess while
installed in cylinder head. Depress part of rocker
arm over adjuster. Normal adjusters should feel very
firm. Spongy adjusters can be bottomed out easily.
b. Remove suspected lash adjusters, and disassem-
bleDo not reuse retainer caps. Do not inter-
change parts and make sure that care and
cleanliness is exercised in the handling of parts.
c. Clean out dirt and varnish with solvent.
d. Reassemble with engine oil.
e. Check for sponginess.
f. If still spongy, replace with new adjuster.
INSPECTION (ENGINE OIL LEAKS IN GENERAL)
Begin with a through visual inspection of the
engine, particularly at the area of the suspected leak.
If an oil leak source is not readily identifiable, the
following steps should be followed:
(1) Do not clean or degrease the engine at this
time because some solvents may cause rubber to
swell, temporarily stopping the leak.
9 - 8 ENGINENS
DIAGNOSIS AND TESTING (Continued)

(2) Add an oil soluble dye (use as recommended by
manufacturer). Start the engine and let idle for
approximately 15 minutes. Check the oil dipstick to
make sure the dye is thoroughly mixed as indicated
with a bright yellow color under a black light.
(3) Using a black light, inspect the entire engine
for fluorescent dye, particularly at the suspected area
of oil leak. If the oil leak is found and identified,
repair per service manual instructions.
(4) If dye is not observed, drive the vehicle at var-
ious speeds for approximately 24km (15 miles), and
repeat inspection.
(5)If the oil leak source is not positively
identified at this time, proceed with the air leak
detection test method as follows:
(6) Disconnect the fresh air hose (makeup air) at
the cylinder head cover and plug or cap the nipple on
the cover.
(7) Remove the PCV valve hose from the cylinder
head cover. Cap or plug the PCV valve nipple on the
cover.
(8) Attach an air hose with pressure gauge and
regulator to the dipstick tube.
CAUTION: Do not subject the engine assembly to
more than 20.6 kpa (3 PSI) of test pressure.
(9) Gradually apply air pressure from 1 psi to 2.5
psi maximum while applying soapy water at the sus-
pected source. Adjust the regulator to the suitable
test pressure that provide the best bubbles which
will pinpoint the leak source. If the oil leak is
detected and identified, repair per service manual
procedures.
(10) If the leakage occurs at the rear oil seal area,
refer to the section, Inspection for Rear Seal Area
Leak.
(11) If no leaks are detected, turn off the air sup-
ply and remove the air hose and all plugs and caps.
Install the PCV valve and breather cap hose. Proceed
to next step.
(12) Clean the oil off the suspect oil leak area
using a suitable solvent. Drive the vehicle at various
speeds approximately 24 km (15 miles). Inspect the
engine for signs of an oil leak by using a black light.INSPECTION FOR REAR SEAL AREA LEAKS
Since it is sometimes difficult to determine the
source of an oil leak in the rear seal area of the
engine, a more involved inspection is necessary. The
following steps should be followed to help pinpoint
the source of the leak.
If the leakage occurs at the crankshaft rear oil seal
area:
(1) Disconnect the battery.
(2) Raise the vehicle.
(3) Remove torque converter or clutch housing
cover and inspect rear of block for evidence of oil.
Use a black light to check for the oil leak. If a leak is
present in this area remove transmission for further
inspection.
(a) Circular spray pattern generally indicates
seal leakage or crankshaft damage.
(b) Where leakage tends to run straight down,
possible causes are a porous block, oil galley cup
plug, bedplate to cylinder block mating surfaces
and seal bore. See proper repair procedures for
these items.
(4) If no leaks are detected, pressurized the crank-
case as outlined in the, Inspection (Engine oil Leaks
in general)
CAUTION: Do not exceed 20.6 kPa (3 psi).
(5) If the leak is not detected, very slowly turn the
crankshaft and watch for leakage. If a leak is
detected between the crankshaft and seal while
slowly turning the crankshaft, it is possible the
crankshaft seal surface is damaged. The seal area on
the crankshaft could have minor nicks or scratches
that can be polished out with emery cloth.
CAUTION: Use extreme caution when crankshaft
polishing is necessary to remove minor nicks and
scratches. The crankshaft seal flange is especially
machined to complement the function of the rear oil
seal.
(6) For bubbles that remain steady with shaft
rotation, no further inspection can be done until dis-
assembled.
(7) After the oil leak root cause and appropriate
corrective action have been identified. Refer to Rear
Crankshaft Seals, for proper replacement procedures.
NSENGINE 9 - 9
DIAGNOSIS AND TESTING (Continued)

ENGINE DIAGNOSISÐPERFORMANCE
CONDITION POSSIBLE CAUSE CORRECTION
ENGINE WILL NOT START 1. Weak battery. 1. Test battery. Charge or replace
as necessary.Refer to Group 8A,
Battery.
2. Corroded or loose battery
connections.2. Clean and tighten battery
connections. Apply a coat of light
mineral grease to terminals.
3. Faulty starter. Test starting system. Refer to Group
8B, Starting.
4. Moisture on ignition wires. 4. Remove moisture from wires.
5. Faulty ignition cables. 5. Replace any cracked or shorted
cables.
6. Faulty coil or control unit. 6. Test and replace as needed.
Refer to Group 8D, Ignition System
7. Incorrect spark plug gap. 7. Set gap. Refer to Group 8D,
Ignition System.
8. Contamination in fuel system. 8. Clean system and replace fuel
filter.
9. Faulty fuel pump. 9. Test fuel pump and replace as
needed. Refer to Group 14, Fuel
System.
ENGINE STALLS OR IDLES
ROUGH1. Idle speed too low. 1. Test minimum air flow. Refer to
Group 14, Fuel System.
2. Incorrect fuel mixture. 2. Refer to Group 14, Fuel System.
3. Intake manifold leakage. 3. Inspect intake manifold, manifold
gasket, and vacuum hoses. Refer to
Group 11, Exhaust System and
Intake Manifold.
4. Incorrect ignition wiring. 4. Install correct wiring.
5. Faulty coil(s) 5. Test and replace as necessary.
Refer to Group 8D, Ignition System.
ENGINE LOSS OF POWER 1. Dirty or incorrectly gapped plugs. 1. Clean plugs and set gap. Refer to
Group 8D, Ignition System.
2. Contamination in fuel system. 2. Clean system and replace fuel
filter.
3. Faulty fuel pump. 3. Test and replace as necessary.
Refer to Group 14, Fuel System.
4. Incorrect valve timing. 4. Correct valve timing.
5. Leaking cylinder head gasket. 5. Replace cylinder head gasket.
6. Low compression. 6. Test compression of each
cylinder.
7. Burned, warped, or pitted valves. 7. Replace valves.
8. Plugged or restricted exhaust
system.8. Install new parts, as necessary.
9. Faulty ignition cables. 9. Replace any cracked or shorted
cables.
10. Faulty coil(s). 10. Test and replace as necessary.
Refer to Group 8D, Ignition System.
9 - 10 ENGINENS
DIAGNOSIS AND TESTING (Continued)

CONDITION POSSIBLE CAUSE CORRECTION
ENGINE MISSES ON
ACCELERATION1. Dirty or incorrectly gapped spark
plugs.1. Clean spark plugs and set gap.
Refer to Group 8D, Ignition System.
2. Contamination in Fuel System. 2. Clean fuel system and replace
fuel filter.
3. Burned, warped, or pitted valves. 3. Replace valves.
4. Faulty coil(s). 4. Test and replace as necessary.
Refer to Group 8D, Ignition System.
ENGINE MISSES AT HIGH SPEED 1. Dirty or incorrect spark plug gap. 1. Clean spark plugs and set gap.
Refer to Group 8D, Ignition System.
2. Faulty coil(s). 2. Test and replace as necessary.
Refer to Group 8D, Ignition System.
3. Dirty fuel injector(s). Test and replace as necessary.
Refer to Group 14, Fuel System.
4. Contamination in fuel system. 4. Clean system and replace fuel
filter.
NSENGINE 9 - 11
DIAGNOSIS AND TESTING (Continued)

ENGINE DIAGNOSISÐMECHANICAL
CONDITION POSSIBLE CAUSES CORRECTION
NOISY VALVES 1. High or low oil level in
crankcase.1. Check for correct oil level.
2. Thin or diluted oil. 2. Change oil to correct viscosity.
3. Low oil pressure. 3. Check engine oil level.
4. Dirt in tappets/lash adjusters. 4. Replace rocker arm/hydraulic
lash adjuster assembly.
5. Worn rocker arms. 5. Inspect oil supply to rocker arms.
6. Worn tappets/lash adjusters. 6. Install new rocker arm/hydraulic
lash adjuster assembly.
7. Worn valve guides. 7. Ream and install new valves with
oversize stems.
8. Excessive runout of valve seats
on valve faces.8. Grind valve seats and valves.
9. Missing adjuster pivot. 9. Replace rocker arm/hydraulic
lash adjuster assembly.
CONNECTING ROD NOISE 1. Insuffient oil supply. 1. Check engine oil level.
2. Low oil pressure. 2. Check engine oil level. Inspect oil
pump relief valve and spring.
3. Thin or diluted oil. 3. Change oil to correct viscosity.
4. Excessive bearing clearance. 4. Measure bearings for correct
clearance. Repair as necessary.
5. Connecting rod journal
out-of-round.5. Replace crankshaft or grind
surface.
6. Misaligned connecting rods. 6. Replace bent connecting rods.
MAIN BEARING NOISE 1. Insufficient oil supply. 1. Check engine oil level.
2. Low oil pressure. 2. Check engine oil level. Inspect oil
pump relief valve and spring.
3. Thin or diluted oil. 3. Change oil to correct viscosity.
4. Excessive bearing clearance. 4. Measure bearings for correct
clearance. Repair as necessary.
5. Excessive end play. 5. Check thrust bearing for wear on
flanges.
6. Crankshaft journal out-of-round
or worn.6. Replace crankshaft or grind
journals.
7. Loose flywheel or torque
converter.7. Tighten to correct torque.
OIL PRESSURE DROP 1. Low oil level. 1. Check engine oil level.
2. Faulty oil pressure sending unit. 2. Install new sending unit.
3. Low oil pressure. 3. Check sending unit and main
bearing oil clearance.
4. Clogged oil filter. 4. Install new oil filter.
5. Worn parts in oil pump. 5. Replace worn parts or pump.
6. Thin or diluted oil. 6. Change oil to correct viscosity.
7. Excessive bearing clearance. 7. Measure bearings for correct
clearance.
8. Oil pump relief valve stuck. 8. Remove valve and inspect, clean,
or replace.
9. Oil pump suction tube loose. 9. Remove oil pan and install new
tube or clean, if necessary.
10. Oil pump cover warped or
cracked.10. Install new oil pump.
9 - 12 ENGINENS
DIAGNOSIS AND TESTING (Continued)