Section 03-00: Engine, Service
1996 All F-150, F-250, F-350, F-Super Duty and Bronco Vehicles Equipped with 4.9L, 5.0L, 5.8L or 7.5L Gasoline Engines, and 7.3L Diesel Engines Workshop Manual
DIAGNOSIS AND TESTING

Symptom Chart — Engine Diagnosis

ENGINE DIAGNOSIS
ConditionPossible SourceAction
  • Difficult Starting
  • Burnt valve.
  • REPLACE valve.
 
  • Worn piston.
  • REPLACE piston.
 
  • Worn piston ring(s).
  • REPLACE piston ring(s).
 
  • Worn cylinder.
  • Damaged cylinder head gasket.
  • SERVICE or REPLACE cylinder block.
 
  • Malfunctioning or damaged fuel system.
  • REPLACE cylinder head gasket.
  • REFER to Powertrain Control/Emissions Diagnosis Manual OBDI or OBDII.
 
  • Malfunctioning or damaged ignition system.
  • REFER to Powertrain Control/Emissions Diagnosis Manual OBDI or OBDII.
  • Poor Idling
  • Intake manifold vacuum leak.
  • CHECK and REPLACE vacuum lines and caps.
  • CHECK and REPLACE intake manifold and upper intake gaskets.
 
  • Damaged hydraulic valve tappet.
  • REPLACE hydraulic valve tappet.
 
  • Damaged hydraulic valve tappet guide.
  • REPLACE hydraulic valve tappet guide.
 
  • Improper valve-to-valve seat contact.
  • REPLACE valve and/or valve seat.
 
  • Damaged cylinder head gasket.
  • REPLACE cylinder head gasket.
 
  • Malfunctioning or damaged fuel system.
  • REFER to Powertrain Control/Emissions Diagnosis Manual OBDI or OBDII.
 
  • Malfunctioning or damaged ignition system.
  • REFER to Powertrain Control/Emissions Diagnosis Manual OBDI or OBDII.
  • Abnormal Combustion
  • Damaged hydraulic valve tappet.
  • REPLACE hydraulic valve tappet.
 
  • Damaged hydraulic valve tappet guide.
  • REPLACE hydraulic valve tappet guide.
 
  • Burnt or sticking valve.
  • SERVICE or REPLACE valve.
 
  • Weak or broken valve spring.
  • REPLACE valve spring.
 
  • Carbon accumulation in combustion chamber.
  • ELIMINATE carbon buildup.
 
  • Malfunctioning or damaged fuel system.
  • REFER to Powertrain Control/Emissions Diagnosis Manual OBDI or OBDII.
 
  • Malfunctioning or damaged ignition system.
  • REFER to Powertrain Control/Emissions Diagnosis Manual OBDI or OBDII.
  • Excessive Oil Consumption
  • Worn piston ring groove.
  • REPLACE piston.
 
  • Sticking piston ring(s).
  • SERVICE or REPLACE piston ring(s).
 
  • Worn piston or cylinder.
  • SERVICE and/or REPLACE piston or cylinder block.
 
  • Worn valve stem seal.
  • REPLACE valve stem seal.
 
  • Worn valve stem or valve guide.
  • REPLACE valve stem and guide.
 
  • Leaking oil.
  • SERVICE oil leakage.
  • Hard Start/No Start
  • Low-pressure oil pump.
 
  • High-pressure oil pump.
  • PERFORM high-pressure oil pump diagnostics and testing. REFER to Powertrain Control/Emissions Diagnosis Manual OBDI or OBDII.
 
  • Oil reservoir empty.
  • Engine Noise
  • Excessive main bearing oil clearance.
  • ADJUST clearance or REPLACE main bearing.
 
  • Seized or heat damaged main bearing.
  • REPLACE main bearing.
 
  • Excessive crankshaft end play.
  • ADJUST end play or REPLACE crankshaft.
 
  • Excessive connecting rod bearing oil clearance.
  • ADJUST clearance or REPLACE connecting rod.
 
  • Heat damaged connecting rod bearing.
  • REPLACE connecting rod bearing.
 
  • Damaged connecting rod bushing.
  • REPLACE connecting rod bushing.
 
  • Worn cylinder.
  • SERVICE or REPLACE cylinder block.
 
  • Worn piston or piston pin.
  • REPLACE piston or piston pin.
 
  • Damaged piston ring(s).
  • REPLACE piston ring(s).
 
  • Bent connecting rod.
  • REPLACE connecting rod.
 
  • Malfunctioning hydraulic valve tappet.
  • REPLACE hydraulic valve tappet.
 
  • Excessive hydraulic valve tappet clearance.
  • ADJUST clearance or REPLACE hydraulic valve tappet guide.
 
  • Broken valve spring.
  • REPLACE valve spring.
 
  • Excessive valve guide clearance.
  • SERVICE clearance or REPLACE valve guide/stem.
 
  • Malfunctioning or damaged cooling system.
 
  • Malfunctioning or damaged fuel system.
  • REFER to Powertrain Control/Emissions Diagnosis Manual OBDI or OBDII.
 
  • Leaking exhaust system.
  • SERVICE exhaust leakage.
 
  • Improper drive belt tension.
 
  • Malfunctioning generator bearing.
 
  • Loose timing chain.
  • ADJUST or REPLACE timing chain.
 
  • Damaged timing belt tensioner.
  • REPLACE timing belt tensioner.
 
  • Malfunctioning water pump bearing.
  • Insufficient Power
  • Malfunctioning hydraulic valve tappet.
  • REPLACE hydraulic valve tappet.
 
  • Damaged hydraulic valve tappet guide.
  • REPLACE hydraulic valve tappet guide.
 
  • Compression leakage at valve seat.
  • SERVICE or REPLACE valve, valve seat and/or cylinder head.
 
  • Seized valve stem.
  • REPLACE valve stem.
 
  • Weak or broken valve spring.
  • REPLACE valve spring.
 
  • Damaged cylinder head gasket.
  • REPLACE cylinder head gasket.
 
  • Cracked or distorted cylinder head.
  • REPLACE cylinder head.
 
  • Damaged, worn or sticking piston ring(s).
  • SERVICE or REPLACE piston ring(s).
 
  • Worn or damaged piston.
  • REPLACE piston.
 
  • Malfunctioning or damaged fuel system.
  • Malfunctioning or damaged ignition system.
  • REFER to Powertrain Control/Emissions Diagnosis Manual OBDI or OBDII.
 
  • Slipping transmission.
 
  • Dragging brakes.
 
  • Incorrect tire size.
 
  • Damaged or plugged exhaust system.