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Engine Symptom Chart: Notes

ENGINE SYMPTOM CHART

Problem Possible Cause Action
  • Difficult Starting
  • Damaged ignition system.
See TEST 17: IGNITION SCOPE TEST  .
  • Damaged fuel
See TEST 5: FUEL DELIVERY SYSTEM  .
  • Damaged starting system.
See STARTING SYSTEM SYMPTOM TROUBLESHOOTING CHART  .
  • Damaged charger system/battery.
See CHARGING SYSTEM COMPONENT TESTS
  • Burnt valve.
Replace valve. Refer to 2.5L 4-CYLINDER article in Engine . Refer to 3.0L V6 article in Engine . Refer to 4.0L V6 article in Engine .
  • Worn piston.
Replace piston and piston head. Refer to 2.5L 4-CYLINDER article in Engine . Refer to 3.0L V6 article in Engine . Refer to 4.0L V6 article in Engine .
  • Worn piston rings.
Replace piston ring. Refer to 2.5L 4-CYLINDER article in Engine . Refer to 3.0L V6 article in Engine . Refer to 4.0L V6 article in Engine .
  • Worn cylinder.
Repair of replace cylinder block. Refer to 2.5L 4-CYLINDER article in Engine . Refer to 3.0L V6 article in Engine . Refer to 4.0L V6 article in Engine .
  • Damaged head gasket.
Replace head gasket.
See REMOVAL & INSTALLATION in 2.5L 4-CYLINDER article in Engine for 2.5L engine.
See REMOVAL & INSTALLATION in 3.0L V6 article in Engine for 3.0L engine.
See REMOVAL & INSTALLATION in 4.0L V6 article in Engine for 4.0L engine.
  • Poor Idling
  • Vacuum leaks.
See ENGINE COMPONENT TESTS .
  • Malfunctioning or damaged ignition system.
See TEST 17: IGNITION SCOPE TEST  .
  • Malfunctioning or damaged fuel system.
See TEST 5: FUEL DELIVERY SYSTEM  .
  • Damaged valve tappet (4.0L engine) or lash adjuster (2.5L engine).
Replace valve tappet or lash adjuster.
See REMOVAL & INSTALLATION in 2.5L 4-CYLINDER article in Engine or REMOVAL & INSTALLATION in 4.0L V6 article in Engine.
  • Damaged valve tappet guide or lash adjuster (3.0L engine).
Replace valve tappet guide or valve tappet.
See REMOVAL & INSTALLATION in 3.0L V6 article in Engine.
  • Improper valve-to-valve seat contact.
Repair or replace valve or valve seat. Refer to REMOVAL & INSTALLATION in 2.5L 4-CYLINDER article in Engine . Refer to REMOVAL & INSTALLATION in 3.0L V6 article in Engine . Refer to REMOVAL & INSTALLATION in 4.0L V6 article in Engine .
  • Damaged head gasket.
Replace head gasket.
See CYLINDER HEAD in 2.5L 4-CYLINDER article in Engine for 2.5L engine.
See CYLINDER HEAD in 3.0L V6 article in Engine for 3.0L engine.
See CYLINDER HEAD in 4.0L V6 article in Engine
  • Abnormal Combustion
  • Malfunctioning or damaged fuel system.
See TEST 5: FUEL DELIVERY SYSTEM  .
  • Malfunctioning or damaged ignition system.
See TEST 17: IGNITION SCOPE TEST  .
  • Damaged valve tappet (4.0L engine) or lash adjuster (2.5L engine).
Replace valve tappet or lash adjuster.
See REMOVAL & INSTALLATION in 4.0L V6 article in Engine
  • Damaged valve tappet guide or valve tappet (3.0L engine).
Replace valve tappet guide or valve tappet.
See REMOVAL & INSTALLATION in 3.0L V6 article in Engine.
  • Burnt or sticking valve.
Repair or replace valve. Refer to 2.5L 4-CYLINDER article in Engine . Refer to 3.0L V6 article in Engine . Refer to 4.0L V6 article in Engine .
  • Weak or broken valve spring.
Replace valve spring. Refer to 2.5L 4-CYLINDER article in Engine . Refer to 3.0L V6 article in Engine . Refer to 4.0L V6 article in Engine .
  • Carbon accumulation in combustion chamber.
  • Eliminate carbon buildup.
  • Leaking oil.
  • Repair oil leakage.
  • Malfunctioning PCV system.
  • Repair or replace the necessary components.
  • Worn valve stem seal.
  • Replace valve stem seal. Refer to 2.5L 4-CYLINDER article in Engine . Refer to 3.0L V6 article in Engine . Refer to 4.0L V6 article in Engine .
  • Worn valve stem or valve guide.
  • Replace valve stem and valve guide. Refer to 2.5L 4-CYLINDER article in Engine . Refer to 3.0L V6 article in Engine . Refer to 4.0L V6 article in Engine .
  • Sticking piston rings.
  • Repair or replace piston rings. Refer to 2.5L 4-CYLINDER article in Engine . Refer to 3.0L V6 article in Engine . Refer to 4.0L V6 article in Engine .
  • Worn piston ring groove.
  • Replace piston and piston pin. Refer to 2.5L 4-CYLINDER article in Engine . Refer to 3.0L V6 article in Engine . Refer to 4.0L V6 article in Engine .
  • Excessive Oil Consumption
  • Worn piston or cylinder.
  • Repair or replace piston or cylinder block. Refer to 2.5L 4-CYLINDER article in Engine . Refer to 3.0L V6 article in Engine . Refer to 4.0L V6 article in Engine .
  • Engine Noise
  • Leaking exhaust system.
  • Repair exhaust leakage.
  • Improper drive belt tension.
See COOLING SYSTEM SPECIFICATIONS & DRIVE BELT ROUTING article in Engine.
  • Malfunction generator bearing.
See GENERATORS & REGULATORS article in Electrical .
  • Malfunctioning water pump bearing.
See WATER PUMP in 2.5L 4-CYLINDER article in Engine for 2.5L engine.
See WATER PUMP in 3.0L V6 article in Engine for 3.0L engine.
See WATER PUMP in 4.0L V6 article in Engine
  • Malfunctioning or damaged cooling system.
Repair cooling system as necessary.
  • Malfunctioning or damaged fuel system.
See TEST 5: FUEL DELIVERY SYSTEM  .
  • Loose timing chain/belt.
  • Damaged timing chain tensioner.
  • Replace timing chain tensioner
  • Excessive main bearing clearance.
See ENGINE COMPONENT TESTS .
  • Seized or heat damaged crankshaft main bearing.
  • Replace crankshaft main bearing. Refer to 2.5L 4-CYLINDER article in Engine . Refer to 3.0L V6 article in Engine . Refer to 4.0L V6 article in Engine .
  • Excessive crankshaft end play.
  • Replace thrust bearing or crankshaft. Refer to 2.5L 4-CYLINDER article in Engine . Refer to 3.0L V6 article in Engine . Refer to 4.0L V6 article in Engine .
  • Excessive connecting rod bearing clearance.
  • Replace connecting rod bearing or connecting rod. Refer to 2.5L 4-CYLINDER article in Engine . Refer to 3.0L V6 article in Engine . Refer to 4.0L V6 article in Engine .
  • Heat damaged connecting rod bearing.
  • Replace connecting rod bearing. Refer to 2.5L 4-CYLINDER article in Engine . Refer to 3.0L V6 article in Engine . Refer to 4.0L V6 article in Engine .
  • Damaged connecting rod bushing.
  • Replace connecting rod bushing. Refer to 2.5L 4-CYLINDER article in Engine . Refer to 3.0L V6 article in Engine . Refer to 4.0L V6 article in Engine .
  • Worn cylinder.
  • Repair or replace cylinder block. Refer to 2.5L 4-CYLINDER article in Engine . Refer to 3.0L V6 article in Engine . Refer to 4.0L V6 article in Engine .
  • Worn piston or piston pin.
  • Replace piston or piston pin. Refer to 2.5L 4-CYLINDER article in Engine . Refer to 3.0L V6 article in Engine . Refer to 4.0L V6 article in Engine .
  • Damaged piston rings.
  • Bent connecting rod.
  • Malfunctioning valve tappet or lash adjuster.
  • Excessive valve tappet or lash adjuster clearance.
  • Adjust clearance or replace valve tappet guide or valve tappet. Refer to 2.5L 4-CYLINDER article in Engine . Refer to 3.0L V6 article in Engine . Refer to 4.0L V6 article in Engine .
  • Broken valve spring.
  • Excessive valve guide clearance.
  • Repair clearance or replace valve guide and stem. Refer to 2.5L 4-CYLINDER article in Engine . Refer to 3.0L V6 article in Engine . Refer to 4.0L V6 article in Engine .
  • Insufficient Power
  • Malfunctioning or damaged ignition system.
See TEST 17: IGNITION SCOPE TEST  .
  • Malfunctioning or damaged fuel system.
See TEST 5: FUEL DELIVERY SYSTEM  .
  • Damaged or plugged exhaust system.
  • Inspect exhaust system.
  • Incorrect tire size.
Refer to owner's manual.
  • Dragging brakes.
Repair brake system as necessary.
  • Slipping transmission.
See DIAGNOSIS - 4R44E article in Transmission or DIAGNOSIS - 5R55E article in Transmission .
  • Malfunctioning valve tappet (4.0L engine) or lash adjuster (2.5L engine).
  • Damaged valve tappet guide or valve tappet (3.0L engine).
  • Compression leakage at valve seat.
  • Repair or replace valve, valve seat or cylinder head. Refer to 2.5L 4-CYLINDER article in Engine . Refer to 3.0L V6 article in Engine . Refer to 4.0L V6 article in Engine .
  • Seized valve stem.
  • Weak or broken valve spring.
  • Worn or damaged cam.
  • Damaged head gasket.
  • Replace head gasket.
  • Cracked or distorted cylinder head.
See CYLINDER HEAD in 2.5L 4-CYLINDER article in Engine for 2.5L engine.
See CYLINDER HEAD in 3.0L V6 article in Engine for 3.0L engine.
See CYLINDER HEAD in 4.0L V6 article in Engine .
  • Damaged, worn or sticking piston ring(s).
  • Repair or replace piston ring(s). Refer to 2.5L 4-CYLINDER article in Engine . Refer to 3.0L V6 article in Engine . Refer to 4.0L V6 article in Engine .
  • Worn or damaged piston.
  • Replace piston and piston pin. Refer to 2.5L 4-CYLINDER article in Engine . Refer to 3.0L V6 article in Engine . Refer to 4.0L V6 article in Engine