Common starting system problems

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Common starting system problems
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• In a no-crank problem, the engine crankshaft does
  NOT rotate properly with the ignition key at
  start. The most common causes are a dead battery,
  poor electrical connection, or faulty system
  component.

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• A slow cranking condition occurs when the engine
  crankshaft rotates at lower than normal speed. It
  is usually caused by the same kind of faults
  producing a no-crank problem.

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• A buzzing or clicking sound from the solenoid,
  without cranking, is commonly due to a discharged
  battery or poor battery cable connections. Low
  current flow is causing the solenoid plunger to
  rapidly kick in and out, making a clattering
  sound.

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• A single click sound, without cranking, may point
  to a bad starting motor, burned solenoid
  contacts, dead battery, or engine mechanical
  problems. The click is usually the solenoid
  closing or the pinion gear contacting the
  flywheel gear.

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• A humming sound, after momentary engine cranking,
  may be due to a bad starter overrunning clutch or
  worn pinion gear unit. Pinion gear wear can make
  the gear disengage from the flywheel gear too
  soon. This can let the motor armature spin
  rapidly, with a humming sound.

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• A metallic grinding noise may be caused by broken
  flywheel teeth or pinion gear teeth wear. The
  grinding may be the gears clashing against each
  other.

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• Normal cranking, without starting, is usually NOT
  caused by the starting system. There may be
  trouble in the fuel or ignition systems. With a
  diesel engine, check engine cranking speed. If
  cranking rpm is low, the diesel may not start.

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• Sometimes the starting solenoid feeds current to
  the ignition system after engine starting. If the
  engine starts and then dies (stops running) as
  the ignition key is released, check voltage from
  the solenoid to the ignition system. You could
  have an open wire or connection in the solenoid
  circuit. A defective ignition switch or wiring
  problem are other possible causes.

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The End

• This information is taken from the text book
  Modern Automotive Technology by James Duffy. You
  must read it if you want to learn about cars
  there is a lot of info in this book.
• Mr. Salisbury, author of powerpoint.