Starter Condition Diagnosis

STARTER CONDITION DIAGNOSIS

STARTER DIAGNOSIS / TESTING OVERRUN - EXPLODED COMMUTATOR

The starting system on most vehicles or engine applications requires very little • Relay remains engaged (key switch held excessively in “start” position) maintenance. As recommended by most vehicle manufacturers (see factory service manual), a charged battery and properly maintained electrical connections • Starter pinion turns at flywheel speed (engine speed) can provide years of trouble-free starter service. • Commutator explodes causing damage to brushes, brush holder assem- Starting Circuit Basic Inspection bly, and commutator • Inspect and/or test battery condition • Inspect battery terminals and cables • Inspect and/or test ignition switch, relays, start switches, etc. • Inspect starter motor for damaged wiring, loose connections, missing bolts, etc. • Inspect and/or test condition of vehicle wiring NOTE:

When inspection or testing is required on any vehicle, engine, or related Exploded commutator and Damage to commutator brush- Completely exploded commu- component part, procedures noted in the applicable factory service brush debris. es and brush holder assembly. tator and insulator assembly. manual(s) should always be followed.

CONTINUOUS CRANKING / OVERHEATED RE-ENGAGEMENT - PINION TEETH MESHING PROBLEM

• Low battery voltage resulting in excessive current to starter motor • Starter pinion teeth and flywheel do not mesh properly • Starter pinion gear has excessive wear • Starter commutator overheated, bars on commutator lift from insulator • Operator error (holding the key switch in the “start” position while the • Damage to brushes and/or brush holder assembly engine is operating • Mechanical problem (ignition switch or relay contacts stuck closed)

• Commutator surface is • Commutator surface is burnt. Commutator segment bar has Minor case of re-engagement Extreme case of pinion re- Extreme case of pinion re- glazed. • Commutator segment bar separated, raised and bent (will cause flywheel damage engagement. engagement. • Commutator segment bars missing. (distorted). and have difficulty engaging missing. into flywheel).

MODIFIED STARTER - ALTERED FROM ORIGINAL DESIGN PHYSICAL DAMAGE / ABUSE • Photos below are examples of starters that have been modified. DENSO • These 3 pictures are examples of physical damage (abuse) to starter Corporation designs and engineers all starters to meet specific OEM components and to the starter assembly. requirements.

Epoxy has been added to a This starter housing has been Grease applied to the solenoid Solenoid cover has been struck Key switch terminal insulator Starter to engine mounting bolt damaged key switch terminal modified possibly to fit another contacts. This acts as an insu- repeatedly with a hammer or cover has been damaged. This hole broken off due to mishan- insulator in an attempt to pre- application. lator and prevents current flow. some other foreign object. terminal could possibly ground dling, improper installation, or vent accidental grounding. out on the starter housing. over-torquing of the engine bolt.

SIGNS OF STARTER ABUSE / NEGLECT BASIC STARTER DIAGNOSIS

• Photos below are examples of starters that have been abused or SYMPTOM POSSIBLE CAUSE neglected. Engine will not crank • Battery (low voltage or defective) • Loose battery terminals or defective cables • Defective ignition switch, solenoid, relay, or cut switch • Vehicle engine problem (mechanical)

Noise heard during cranking • Worn bushing or bearing • Worn pinion ring gear or flywheel teeth

Engine cranks slow • Battery (low voltage or defective) • Loose or corroded batttery terminals, cables, or vehicle wiring • Vehicle engine problem (mechanical) • Faulty starter motor

Starter spins freely, but will not • Faulty starter clutch ID tag has been overheated Melted insulation on the starter Normal starter (left), pinion gear crank engine • Defective or worn pinion gear, ring gear or flywheel and has shrunk. This is a sign end housing thru bolts. This is fully retracted. Overheated (right), pinion gear not fully retracted. Once of excessive heat. a definite sign of starter abuse NOTE: (overheated). a starter has become overheated, the return spring loses tension and When inspection or testing is required on any vehicle, engine, or related component part, the pinion gear will not fully retract. procedures noted in the applicable factory service manual(s) should always be followed.