Jim Smart
August 13, 2010

Engine Overheating

  • Stuck thermostat (a misconception; thermostats don't stick, they fail to open).
  • Clogged water pump due to corrosion and/or debris.
  • Clogged radiator or insufficient radiator capacity.
  • Blown cylinder head gasket into water jacket.
  • Collapsed lower radiator hose (only if overheating happens on the highway).
  • Blocked water jackets (freeze plugs, iron particles, and other debris).
  • Wrong pulley sizes, causing water pump to run too fast.
  • Thermostat has been removed (engine will overheat in traffic only).
  • Fan belt slippage.
  • Wrong water pump for application, such as reverse rotation from a late-model 5.0.

Low Oil Pressure

  • Excessive bearing clearances.
  • Oil pump pressure relief valve stuck.
  • Oil pump pick-up loose or bad gasket.
  • Clogged oil pump pick-up.
  • Oil galley plug loose or missing inside the engine.
  • Loose lifter bore clearances.

Battery Won't Stay Charged

  • Alternator or generator not charging.
  • Voltage regulator contacts open or open circuit inside regulator.
  • Battery cells shorted out (known as dead cells; one dead cell causes a weak battery that runs down quickly)
  • Belt slippage.
  • Incorrect pulley size in front dress.
  • Poor electrical connections at alternator, generator, or voltage regulator.
  • Failed alternator diode(s).

Headlights/Taillights Inoperative or Cycle Off and On

  • Defective headlight switch circuit breaker or short circuit.
  • Short circuit can be anywhere between headlight switch and exterior lights.
  • Heads-up: old headlight switches suffer from bad circuit breakers.

Turn Signals Won't Operate

  • Defective turn signal switch.
  • Blown fuse or other reason for no power to switch.
  • Defective flasher.
  • Bulbs burned out at parking or tail lamp.

Taillights/Parking Lights Keep Blowing Fuses

  • Short circuit to ground anywhere between dashboard and lights.
  • Short at socket.
  • Internal short inside bulb.

Electric Clock Inoperative

  • Clock rewind contact points pitted or burned.
  • Clock main spring broken (cannot rewind).
  • Fuse blown.

Parking Brake Will Not Hold

  • Cable adjustment required.
  • Rear brake shoes excessively worn.
  • Rear brake drums glazed.
  • Rear brake shoe struts/springs require inspection.

Brakes Pull To One Side

  • Improper adjustment (too tight on one side, drum brakes only).
  • Stuck disc brake caliper piston.
  • Improper proportioning valve adjustment (rear brakes will tend to come on first).

Pulsing Brake Pedal

  • Warped brake drums or rotors.
  • Damaged or excessively worn disc brake pads.

Clutch Chatters

  • Worn-out clutch pilot bearing.
  • Bent transmission input shaft.
  • Bad input shaft bearing.
  • Clutch disc contamination (oil, grease, debris).
  • Clutch linkage binding.
  • Clutch fork adjustment.

Clutch Slips

  • Worn pressure plate or clutch disc.
  • Contaminated clutch disc.
  • Clutch adjusted too tight.
  • Clutch disc installed backwards.

Manual Transmission Jumps Out Of Gear

  • Maladjusted shifter linkage.
  • Worn-out clutch pilot bushing.
  • Defective detent mechanism (keeps transmission in specific gears)
  • Worn synchronizers

Manual Transmission Noise In Forward Gears

  • Lubricant may be low.
  • Main and/or counter shaft bearings worn or damaged.
  • Synchronizers worn or damaged.

Clutch Pedal Rattles and Pulses

  • Out of balance clutch/flywheel.
  • Release bearing adjustment too tight.
  • Bent transmission input shaft.
  • Worn or damaged clutch pilot bushing.

Automatic Transmission Slips

  • Control pressure low due to defective front pump or damaged seals.
  • Low fluid level (slips worse in turns).
  • Extremely dirty or burned fluid.
  • Clogged transmission filter.
  • Sticking valve body pistons.
  • Worn servo bands, clutches, or clutch piston seals.
  • Defective or improperly adjusted vacuum modulator.

Automatic Transmission Slow To Engage (Any Gear)

  • Low control pressure.
  • Low fluid level.
  • Clogged transmission filter.
  • Extremely dirty or burned fluid.
  • Leaking clutch piston seals and/or servo piston seals (rebuild necessary)
  • Faulty torque converter.

Rear Axle Noise In Forward Gear

  • Lubrication low.
  • Improper viscosity.
  • Excessive ring/pinion backlash.
  • Pinion bearings worn or damaged.
  • Loose fasteners.
  • Rear axle bearings worn out.

Rear Axle Noise While Coasting

  • Ring and pinion backlash too tight.
  • Excessive pinion bearing wear.

Rear Axle Noise In Turns

  • Differential side gears excessively worn or damaged.
  • Differential side or pinion gears binding.

Steering Feels Tight

  • Steering gear backlash too tight.
  • Improper steering gear lubricant.
  • Excessive caster (alignment).
  • Steering linkage damaged.
  • Ball joints binding or seized.

Steering Feels Loose

  • Steering gear backlash loose.
  • Excessive ball joint play.
  • Excessive idler/Pitman arm play.
  • Excessive tie-rod end play.
  • Wheel bearings not adjusted.
  • Excessive toe-in.
  • Worn control arm bushings.

Intermittent Instrument Operation

  • Instrument voltage limiter (voltage regulator) defective if all instruments involved (except ammeter).
  • If problem exists with one instrument only, check sending unit.

Speedometer Erratic

  • Binding speedometer cable.
  • Speedometer head worn out.
  • Damaged speedometer drive gear.

Power Steering Leaks

  • Check hose integrity.
  • Make sure fittings are tight.
  • If fittings are tight, check fitting mating surfaces for nicks.
  • Inspect control valve for leaks around Pitman arm and ball valve.

Driveline Vibration

  • Driveshaft out of balance.
  • Driveshaft run out excessive (bent shaft).
  • Universal joints worn or defective.
  • Excessive slip yoke wear.
  • Differential pinion yoke excessively worn or distorted.