Jeep Wrangler Sport 2010 User manual

2010 ENGINE
3.8L - Service Information - Wrangler
DESCRI TION
DESCRIPTION
Fig. 1: ENGINE IDENTIFICATION
Courtesy of CHRYSLER LLC
The 3.8 Liter (231 cu. in.) engine is 60° V6 engines with cast iron cylinder bloc s and aluminum cylinder
heads. The engine uses a single, bloc mounted camshaft, roller lifters with pushrods to actuate the valves and
either crac ed cap, or standard cap, forged connecting rods. The engine does not have provisions for a free
wheeling valve train.
The firing order is 1-2-3-4-5-6. The left cylinder ban is numbered 2, 4, and 6. The right cylinder ban is
numbered 1, 3, and 5.
The engine identification number is located on the rear of the cylinder bloc just below the cylinder head.
DIAGNOSIS AND TESTING
INTRODUCTION
Engine diagnosis is helpful in determining the causes of malfunctions not detected and remedied by routine
maintenance.
These malfunctions may be classified as either mechanical (e.g., a strange noise), or performance (e.g., engine
idles rough and stalls).
2010 Jeep Wrangler Sport
2010 ENGINE 3.8L - Service Information - Wrangler
2010 Jeep Wrangler Sport
2010 ENGINE 3.8L - Service Information - Wrangler
viernes, 1 de oct bre de 2021 05:18:29 p. m. Page 1 © 2011 Mitchell Repair Information Company, LLC. viernes, 1 de oct bre de 2021 05:22:44 p. m. Page 1 © 2011 Mitchell Repair Information Company, LLC.

Refer to the Engine Mechanical and the Engine Performance diagnostic charts, for possible causes and
corrections of malfunctions. See PERFOR ANCE. See ECHANICAL.
For fuel system diagnosis, refer to Non-DTC Diagnostics/Driveability - Gas - Diagnosis and Testing .
Additional tests and diagnostic procedures may be necessary for specific engine malfunctions that cannot be
isolated with the Service Diagnosis charts. Information concerning additional tests and diagnosis is provided
within the following:
Cylinder Compression Pressure Test: Refer to CYLINDER CO PRESSION PRESSURE TEST.
Cylinder Combustion Pressure Lea age Test: Refer to CYLINDER CO BUSTION PRESSURE
LEAKAGE TEST.
Engine Cylinder Head Gas et Failure Diagnosis: Refer to CYLINDER HEAD GASKET.
Inta e Manifold Lea age Diagnosis: Refer to INTAKE ANIFOLD LEAKS.
Hydraulic Lash Adjuster Noise Diagnosis: Refer to HYDRAULIC LIFTERS.
Engine Oil Lea Inspection: Refer to ENGINE OIL LEAK INSPECTION.
PERFOR ANCE
CONDITION POSSIBLE CAUSE CORRECTION
ENGINE WILL NOT START 1. Wea battery. 1. Test battery. Charge or replace
as necessary
Refer to Electrical/Battery
System - Diagnosis and Testing .
2. Corroded or loose battery
connections.
2. Clean and tighten battery
connections. Apply a coat of light
mineral grease to terminals.
3. Faulty starter. 3. Test starting system. Refer to
Electrical/Starting - Diagnosis
and Testing .
4. Faulty coil(s) or control unit. 4. Test and replace as needed.
(Refer to Appropriate Diagnostic
Information)
5. Incorrect spar plug gap. 5. Set gap. Refer to
Electrical/Ignition Control -
Specifications .
6. Contamination in fuel system. 6. Clean system and replace fuel
filter.
7. Faulty fuel pump. 7. Test fuel pump and replace as
needed. (Refer to Appropriate
Diagnostic Information)
8. Incorrect engine timing. 8. Chec for a s ipped timing
belt/chain.
ENGINE STALLS OR IDLES
ROUGH
1. Idle speed too low. 1. Test minimum air flow. (Refer
to Appropriate Diagnostic
2010 Jeep Wrangler Sport
2010 ENGINE 3.8L - Service Information - Wrangler
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Information)
2. Incorrect fuel mixture. 2. (Refer to Appropriate
Diagnostic Information)
3. Inta e manifold lea age. 3. Inspect inta e manifold,
manifold gas et, and vacuum
hoses.
4. Faulty ignition coil(s). 4. Test and replace as necessary.
(Refer to Appropriate Diagnostic
Information)
ENGINE LOSS OF POWER 1. Dirty or incorrectly gapped
plugs.
1. Clean plugs and set gap.
2. Contamination in fuel system. 2. Clean system and replace fuel
filter.
3. Faulty fuel pump. 3. Test and replace as necessary.
(Refer to Appropriate Diagnostic
Information)
4. Incorrect valve timing. 4. Correct valve timing.
5. Lea ing cylinder head gas et. 5. Replace cylinder head gas et.
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. Perform exhaust restriction test.
Refer to Exhaust System -
Diagnosis and Testing . Install
new parts, as necessary.
9. Faulty ignition coil(s). 9. Test and replace as necessary.
(Refer to Appropriate Diagnostic
Information)
ENGINE MISSES ON
ACCELERATION
1. Dirty or incorrectly gapped
spar plugs.
1. Clean spar plugs and set gap.
2. Contamination in Fuel System. 2. Clean fuel system and replace
fuel filter.
3. Burned, warped, or pitted
valves.
3. Replace valves.
4. Faulty ignition coil(s). 4. Test and replace as necessary.
(Refer to Appropriate Diagnostic
Information)
ENGINE MISSES AT HIGH
SPEED
1. Dirty or incorrect spar plug
gap.
1. Clean spar plugs and set gap.
2. Faulty ignition coil(s). 2. Test and replace as necessary.
(Refer to Appropriate Diagnostic
Information)
3. Dirty fuel injector(s). 3. Test and replace as necessary.
(Refer to Appropriate Diagnostic
Information)
2010 Jeep Wrangler Sport
2010 ENGINE 3.8L - Service Information - Wrangler
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ECHANICAL
4. Contamination in fuel system. 4. Clean system and replace fuel
filter.
CONDITION POSSIBLE CAUSES CORRECTION
NOISY VALVES 1. High or low oil level in
cran case.
1. Chec and correct engine oil
level.
2. Thin or diluted oil. 2. Change oil to correct viscosity.
3. Thic oil 3. (a) Change engine oil and filter.
(b) Run engine to operating
temperature.
(c) Change engine oil and filter
again.
4. Low oil pressure. 4. Chec and correct engine oil
pressure problem.
5. Dirt in hydraulic lifters/lash
adjusters.
5. Replace hydraulic lifters/lash
adjusters.
6. Worn roc er arms. 6. Inspect oil supply to roc er
arms.
7. Worn hydraulic lifters/lash
adjusters.
7. Replace hydraulic lifters/lash
adjusters.
8. Worn valve guides. 8. Replace cylinder head
assembly.
9. Excessive runout of valve seats
on valve faces.
9. Grind valve seats and valves.
CONNECTING ROD NOISE 1. Insufficient oil supply. 1. Chec engine oil level.
2. Low oil pressure. 2. Chec engine oil level. Inspect
oil pump relief valve and spring.
3. Thin or diluted oil. 3. Change oil to correct viscosity.
4. Thic oil 4. (a) Change engine oil and filter.
(b) Run engine to operating
temperature.
(c) Change engine oil and filter
again.
5. Excessive bearing clearance. 5. Measure bearings for correct
clearance. Repair as necessary.
6. Connecting rod journal out-of-
round.
6. Replace cran shaft or grind
surface.
7. Misaligned connecting rods. 7. Replace bent connecting rods.
MAIN BEARING NOISE 1. Insufficient oil supply. 1. Chec engine oil level.
2. Low oil pressure. 2. Chec engine oil level. Inspect
oil pump relief valve and spring.
3. Thin or diluted oil. 3. Change oil to correct viscosity.
4. Thic oil 4. (a) Change engine oil and filter.
2010 Jeep Wrangler Sport
2010 ENGINE 3.8L - Service Information - Wrangler
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(b) Run engine to operating
temperature.
(c) Change engine oil and filter
again.
5. Excessive bearing clearance. 5. Measure bearings for correct
clearance. Repair as necessary.
6. Excessive end play. 6. Chec thrust bearing for wear
on flanges.
7. Cran shaft journal out-of-round
or worn.
7. Replace cran shaft or grind
journals.
8. Loose flywheel or torque
converter.
8. Tighten to correct torque.
OIL PRESSURE DROP 1. Low oil level. 1. Chec engine oil level.
2. Faulty oil pressure
sensor/switch.
2. Replace oil pressure
sensor/switch.
3. Low oil pressure. 3. Chec oil pressure
sensor/switch 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. Oil pump relief valve stuc . 7. Remove valve and inspect,
clean, or replace.
8. Oil pump suction tube loose. 8. Remove oil pan and install new
tube or clean, if necessary.
9. Oil pump cover warped or
crac ed.
9. Install new oil pump.
10. Excessive bearing clearance. 10. Measure bearings for correct
clearance.
OIL LEAKS 1. Misaligned or deteriorated
gas ets.
1. Replace gas et(s).
2. Loose fastener, bro en or
porous metal part.
2. Tighten, repair or replace the
part.
3. Misaligned or deteriorated cup
or threaded plug.
3. Replace as necessary.
OIL CONSUMPTION OR
SPARK PLUGS FOULED
1. PCV system malfunction. 1. Chec system and repair as
necessary. (Refer to
EVAPORATIVE E ISSIONS .
2. Worn, scuffed or bro en rings. 2. Hone cylinder bores. Install
new rings.
3. Carbon in oil ring slots. 3. Install new rings.
4. Rings fitted too tightly in
grooves.
4. Remove rings and chec
grooves. If groove is not proper
width, replace piston.
5. Worn valve guide(s). 5. Replace cylinder head
2010 Jeep Wrangler Sport
2010 ENGINE 3.8L - Service Information - Wrangler
viernes, 1 de oct bre de 2021 05:18:29 p. m. Page 5 © 2011 Mitchell Repair Information Company, LLC.

ENGINE OIL LEAK INSPECTION
Begin with a thorough visual inspection of the engine, particularly at the area of the suspected lea . If an oil
lea 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 lea .
2. Add an oil soluble dye (use as recommended by manufacturer). Start the engine and let idle for
approximately 15 minutes. Chec the oil level indicator to ma e sure the dye is thoroughly mixed as
indicated with a bright yellow color under a blac light.
3. Using a blac light, inspect the entire engine for fluorescent dye, particularly at the suspected area of oil
lea . If the oil lea is found and identified, repair as necessary.
4. If dye is not observed, drive the vehicle at various speeds for approximately 24 m (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:
Disconnect the fresh air hose (ma e-up air) at the cylinder head cover and plug or cap the outlet on
the cover.
Remove the PCV valve hose from the cylinder head cover. Cap or plug the PCV valve outlet on the
cover.
Attach an air hose with pressure gauge and regulator to the oil level indicator tube.
Gradually apply air pressure from 1 psi to 2.5 psi maximum while applying soapy water at the
suspected source. Adjust the regulator to the suitable test pressure that provides the best bubbles
which will pinpoint the lea source. If the oil lea is detected and identified, repair per service
information procedures.
If the lea age occurs at the cran shaft rear oil seal area, refer to INSPECTION FOR REAR
SEAL AREA LEAKS.
6. If no lea s are detected, turn off the air supply. Remove the air hose, all plugs, and caps. Install the PCV
valve and fresh air hose (ma e-up air). Proceed to next step.
7. Clean the oil off the suspect oil lea area using a suitable solvent. Drive the vehicle at various speeds
approximately 24 m (15 miles). Inspect the engine for signs of an oil lea by using a blac light.
assembly.
6. Valve stem seal(s) worn or
damaged.
6. Replace seal(s).
CAUTION: Do not subject the engine assembly to more than 20.6 k a (3
SI) of test pressure.
NOTE: If oil leakage is observed at the oil level indicator tube to block location;
remove the tube, clean and reseal using Mopar® Stud AND Bearing Mount
(press fit tube applications only), and for O-ring style tubes, remove tube
and replace the O-ring seal.
2010 Jeep Wrangler Sport
2010 ENGINE 3.8L - Service Information - Wrangler
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INSPECTION FOR REAR SEAL AREA LEAKS
Since it is sometimes difficult to determine the source of an oil lea 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 lea .
If the lea age occurs at the cran shaft rear oil seal area:
1. Disconnect the battery.
2. Raise the vehicle.
3. Remove torque converter or clutch housing cover and inspect rear of bloc for evidence of oil. Use a
blac light to chec for the oil lea . If a lea is present in this area, remove transmission for further
inspection.
a. Circular spray pattern generally indicates seal lea age or cran shaft damage.
b. Where lea age tends to run straight down, possible causes are a porous bloc , oil gallery cup plug,
bedplate to cylinder bloc mating surfaces and seal bore. See proper repair procedures for these
items.
4. If no lea s are detected, pressurize the cran case as previously described in step 5 in ENGINE OIL
LEAK INSPECTION.
5. If the lea is not detected, very slowly turn the cran shaft and watch for lea age. If a lea is detected
between the cran shaft and seal while slowly turning the cran shaft, it is possible the cran shaft seal
surface is damaged. The seal area on the cran shaft could have minor nic s or scratches that can be
polished out with emery cloth.
6. For bubbles that remain steady with shaft rotation, no further inspection can be done until disassembled.
7. After the oil lea root cause and appropriate corrective action have been identified, replace component(s)
as necessary.
CYLINDER CO PRESSION PRESSURE TEST
CAUTION: Do not exceed 20.6 k a (3 psi).
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.
CAUTION: Do not exceed 20.6 k a (3 psi).
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.
2010 Jeep Wrangler Sport
2010 ENGINE 3.8L - Service Information - Wrangler
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The results of a cylinder compression pressure test can be utilized to diagnose several engine malfunctions.
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. Chec engine oil level and add oil if necessary.
2. Drive the vehicle until engine reaches normal operating temperature. Select a route free from traffic and
other forms of congestion, observe all traffic laws, and accelerate through the gears several times bris ly.
3. Remove all spar plugs from engine. As spar plugs are being removed, chec electrodes for abnormal
firing indicators such as fouled, hot, oily, etc. Record cylinder number of spar plug for future reference.
4. Remove the Auto Shutdown (ASD) relay from the Power Distribution Center (PDC).
5. Insert compression gauge adaptor Special Tool 8116 or the equivalent, into the #1 spar plug hole in
cylinder head. Connect the 0-500 psi (Blue) pressure transducer (Special Tool CH7059) with cable
adaptors to the DRBIII®. For Special Tool identification, see Engine - Special Tools.
6. Cran engine until maximum pressure is reached on gauge. Record this pressure as #1 cylinder pressure.
7. Repeat the previous step for all remaining cylinders.
8. Compression should not be less than 689 Pa (100 psi) and not vary more than 25 percent from cylinder
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 compression
pressures are to be used only as a guide to diagnosing engine problems. An engine should not be
disassembled to determine the cause of low compression unless some malfunction is present.
CYLINDER CO BUSTION PRESSURE LEAKAGE TEST
The combustion pressure lea age test provides an accurate means for determining engine condition.
Combustion pressure lea age testing will detect:
Exhaust and inta e valve lea s (improper seating).
Lea s between adjacent cylinders or into water jac et.
Any causes for combustion/compression pressure loss.
Chec the coolant level and fill as required. DO NOT install the pressure cap.
Start and operate the engine until it attains normal operating temperature, then turn the engine OFF.
Clean spar plug recesses with compressed air.
WARNING: DO NOT REMOVE THE RESSURE CA WITH THE SYSTEM HOT AND
UNDER RESSURE BECAUSE SERIOUS BURNS FROM COOLANT CAN
OCCUR.
2010 Jeep Wrangler Sport
2010 ENGINE 3.8L - Service Information - Wrangler
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Remove the spar plugs.
Remove the oil filler cap.
Remove the air cleaner.
Calibrate the tester according to the manufacturer's instructions. The shop air source for testing should maintain
483 Pa (70 psi) minimum, 1,379 Pa (200 psi) maximum, with 552 Pa (80 psi) recommended.
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. Chec for
bubbles in the coolant.
All gauge pressure indications should be equal, with no more than 25% lea age per cylinder.
FOR EXA PLE: At 552 Pa (80 psi) input pressure, a minimum of 414 Pa (60 psi) should be maintained in
the cylinder.
STANDARD ROCEDURE
ENGINE GASKET SURFACE PREPARATION
Fig. 2: PROPER TOOL USAGE FOR SURFACE PREPARATION
Courtesy of CHRYSLER LLC
To ensure engine gas et sealing, proper surface preparation must be performed, especially with the use of
aluminum engine components and multi-layer steel cylinder head gas ets.
Never use the following to clean gas et surfaces:

Metal scraper (1).
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Abrasive pad or paper to clean cylinder bloc and head.
High speed power tool with an abrasive pad or a wire brush (2,3).
Fig. 3: PROPER TOOL USAGE FOR SURFACE PREPARATION
Courtesy of CHRYSLER LLC
Only use the following for cleaning gas et surfaces:
Solvent or a commercially available gas et remover
Plastic or wood scraper (4).
Sealing surfaces must be free of grease or oil residue. Clean surfaces with Mopar® bra e parts cleaner (or
equivalent).
EASURING BEARING CLEARANCE USING PLASTIGAGE
NOTE: Multi-Layer Steel (MLS) head gaskets require a scratch free sealing surface.
2010 Jeep Wrangler Sport
2010 ENGINE 3.8L - Service Information - Wrangler
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