Common starting system problems

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.

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.

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.

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.

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.

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.

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.

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.

The EndThe End

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

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