Oldsmobile STARTER MOTOR NOISE DIAGNOSIS?

The details are as follows :---

The starting, or cranking system consists of the battery, starter motor, ignition switch and related wiring. These components are connected electrically. When the ignition switch is turned to theSTART position (and the theft protection module recognizes the key code, as equipped) battery voltage is applied to the starter solenoid (through the theft deterrent relay, as equipped) S terminal and the solenoid windings are energized. This causes the plunger to move the shift lever, which engages the pinion with the engine flywheel ring gear. The plunger also closes the solenoid contacts, applying battery voltage to the starter motor, which cranks the engine.

When the engine starts, the pinion will over-run and spin at engine speed (rather than starter motor speed) to help prevent flywheel and starter motor damage. When the ignition switch is released (removing the voltage from the solenoid) the plunger return spring disengages the pinion. In order to prevent excessive over-run, the ignition switch should be released as soon as the engine starts.

WARNING

Never operate the starter motor for more than 30 seconds at a time. Allow it to cool for at least two minutes. Overheating, caused by too much cranking, will damage the starter motor.

The vehicles covered by this guide use several different starter motor applications. When obtaining a replacement starter motor, make sure you get the correct unit. In nearly every case, the starter motor is considered non-serviceable which means they are not user-serviceable and must be replaced as an assembly.

Starter motors do not require lubrication. In general, starter motors give little trouble. Most no-start or hard cranking complaints can be traced to a low battery, poor connections, defective fusible link, engine oil too thick for the weather conditions and other non-starter related causes.

Although different starter motors are used on different engines, the removal and installation procedures are very similar. The main differences are getting to the starter (air dam removal or radiator baffle removal requirements on some applications).

STARTER MOTOR NOISE DIAGNOSIS

High-Pitched Whine During Cranking

A high-pitched whine during cranking (before the engine fires), although the engine cranks and starts okay, means the distance it too great between the starter pinion and flywheel. This distance is governed by thin metal shims between the starter motor and the engine block. Likely a shim needs to be removed. This is often the case after a starter motor has been changed. The replacement starter may not fit exactly as the original so shims are normally used to adjust the starter in or out to get proper tooth meshing.

High-Pitched Whine After Engine Fires

A high-pitched whine after the engine fires, as the key is being released, although then engine cranks and starts okay, is sometime an intermittent complaint. It is often diagnosed as starter "hang-in" or a weak solenoid. This usually means the distance is too small between the starter pinion and flywheel. Flywheel runout (out-of-round) contributes to the intermittent nature of the complaint. Again, shimming the starter correctly should cure the problem. The GM shims are generally 0.040 inch (1mm) thick. Install the shims, one at a time, until the noise is gone. GM recommends that you use no more than two shims and do not exceed 0.080 inch (2mm).

Loud "Whoop" Noise

A loud "whoop" after the engine starts, while the starter is still engaged, often sounding like a siren as the engine RPM is increased while the starter is engaged, is usually a starter drive problem. On starters that can be serviced (very few on the vehicles covered by this guide), a new starter drive should solve the problem. On non-serviceable starters, replace the starter assembly.

Rumble, Growl or Knock

A rumble, growl or in severe cases, a knock as the starter is coasting down to a stop after starting the engine may be traced to a bent starter armature. On starters that can be serviced (very few on the vehicles covered by this guide), a new armature (if available) should solve the problem. On non-serviceable starters, replace the starter assembly.

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