Starter - Diesel Models Mercury Topaz I

DESCRIPTION

The 2.0L and 2.4L diesel starting system includes a 4-pole, 4-brush starting motor with a reduction-gear-positive-engagement drive, starter-ignition switch, starter solenoid (starter housing mounted), starter relay, and heavy circuit wiring.

Inside the drive assembly, an overrunning clutch protects the starter motor from being driven to excessive speed by the ring gear when engine starts.

OPERATION

Turning the ignition switch to the "START" position activates the solenoid. The energized solenoid attracts a plunger which engages the drive gear into the ring gear. The plunger closes a set of contacts that allows current to by-pass the energizing coil. This allows the holding coil to keep the starter drive engaged, and passes starting current to the starter motor, allowing the engine to turn over.

ON-VEHICLE TESTS

Note. Before performing tests, clean and connect battery cables. Be sure battery is fully charged. Remove coil high tension wire from distributor and ground it. Place transmission in Neutral and apply parking brake. When making voltmeter connections or jump starting, use special positive terminal block (located near starter relay), and secure negative lead to an engine bolt.

STARTER CRANKING CIRCUIT

1. Disconnect ignition coil secondary wire. Connect a remote control starter switch from the positive battery terminal to the "S" terminal of the starter relay.
2. Connect a voltmeter and crank engine as described in each of the following situations. Connect negative voltmeter lead to starter terminal. Connect positive voltmeter lead to positive battery terminal. Voltage drop should be .5 volt. Connect negative voltmeter lead to battery side of starter relay. Connect positive voltmeter lead to positive battery terminal. Voltage drop should be .1 volt. Connect negative voltmeter lead to starter side of starter relay. Connect positive voltmeter lead to positive battery terminal. Voltage drop should be .3 volt. Connect negative voltmeter lead to negative terminal of battery. Connect positive lead of voltmeter to engine ground. Voltage drop should be .3 volt.
3. If any test does not obtain the correct voltage drop, inspect and repair wiring in the starter cranking circuit.

Scheme 4

1. Connect test equipment (Scheme 4) Be sure that no current is flowing through ammeter and heavy duty carbon pile rheostat portion of the circuit. (Scheme 4): Test Equipment Connections for Starter Load Test Battery must be fully charged.
2. Disconnect the "S" terminal connector from the starter relay and connect a remote control starter switch. Crank the engine and determine the exact voltmeter reading.
3. Stop cranking the engine and reduce the resistance of the carbon pile until voltmeter indicates same reading as was obtained while starter cranked engine.
4. The ammeter will now indicate starter current draw under load. Normal starter load current is less than 375 amps. If load test current is not within specified range, starter motor must be overhauled or replaced.

STARTER NO-LOAD TEST

Note. The starter no-load test will determine such problems as open or shorted windings, rubbing armature, or a bent armature shaft.

1. Connect positive lead of load tester to positive terminal of a fully charged battery. Connect negative lead of load tester to negative battery terminal.
2. Connect voltmeter leads of load tester to positive and negative battery terminals. Connect a jumper wire between negative battery terminal and starter frame. Connect a second jumper wire between positive battery terminal and battery "B" terminal of starter motor solenoid. Connect a third jumper wire between positive battery terminal and solenoid "S" terminal of the starter motor solenoid. (Scheme 5) NOTE: Be sure that no current is flowing through ammeter.
3. Turn rheostat to maximum counterclockwise position. Note the exact voltmeter reading. Disconnect the jumper leads from the starter motor. Reduce resistance of the rheostat until voltmeter reading is the same as when the starter was running. Ammeter will now indicate starter no-load current draw, it should be less than 190 amps.

Test Equipment Connections for Starter No-Load Test Battery must be fully charged. Scheme 5

ARMATURE OPEN CIRCUIT TEST

An open in the armature circuit can be detected by inspecting the commutator for evidence of burning. A spot burned on the commutator is caused by an arc formed every time that segment of the commutator passes under a brush. If burning is detected, replace armature assembly and check for damage to other related components.

ARMATURE & FIELD GROUNDED CIRCUIT TEST

Note. This test will determine if winding insulation has failed, permitting a conductor to contact the frame or armature core.

1. Use an ohmmeter to make continuity check; infinite resistance indicates normal condition. When using a voltmeter, proceed with steps 2) thru 5).
2. To check the armature, connect negative voltmeter lead to negative battery terminal. Connect positive voltmeter lead to commutator. Connect a jumper wire between positive battery terminal and armature core.
3. If voltmeter indicates any voltage, windings are grounded and armature should be replaced.
4. To check field coils, connect a jumper wire between negative battery terminal and starter frame. Connect negative voltmeter lead to positive battery terminal. Connect positive voltmeter lead to field coil eyelet terminal.
5. If voltmeter indicates any voltage, field windings are grounded and should be replaced.

STARTER SOLENOID TEST

Check for continuity, using an ohmmeter, between terminals "S" and "M", and between terminal "S" and ground. If no continuity is present, the wire is broken and the solenoid should be replaced.

DISASSEMBLY

1. Disconnect the solenoid motor terminal from the field coil connection. Remove attaching screws (from solenoid), plunger return spring, and solenoid (rotate solenoid 90 degrees to remove).
2. Remove through-bolts and brush end plate. Remove brushes, springs, and plastic brush holders. Note location of brush holder in respect to brush terminals. Remove frame and armature assemblies.
3. Remove screw and gear housing. Remove plunger, lever pivot screw, pivot, and lever assembly. Remove gear, output shaft, and drive assembly. Remove thrust washer, retainer, drive stop ring, and slide drive assembly from output shaft.

CLEANING & INSPECTION

Use a brush or compressed air to clean field coils, armature, brush end plate, drive end housing, and starter drive. Wash other parts in suitable solvent. Check brush holders for broken springs and insulated brush holders for shorts-to-ground. Tighten any loose rivets. Replace brushes if worn to 1/4" length. Check commutator for rough or worn surface, and for runout more than .005" (.127 mm) out of round. Service as necessary.

REASSEMBLY

1. Apply a thin coat of Lubriplate 777 on armature shaft splines. Install slide drive assembly onto shaft, new stop ring, retainer, and thrust washer. At drive end housing, install shaft and drive assembly.
2. To install plunger and lever assembly, make sure lever notches engage flange ears of starter drive. Install lever pin screw and tighten. Lubricate gear and washer, then install on end of output shaft.
3. Press grommet into starter frame at field lead position. Install frame assembly to gear housing and make sure grommet is positioned in notch of gear housing.
4. Install brush holder and line up notches with ground brush terminals. Brush holder is symmetrical and can be installed in either notch or brush holder.
5. Install brushes and springs. To prevent grounding, positive brush leads must be installed in their respective slots. Install brush end plate (be certain end plate insulator is in proper location in end plate) and install housing bolts. NOTE: To install starter to vacuum pump support bracket properly, make sure threaded hole of protruding ear in brush end plate is oriented correctly.
6. Install solenoid plunger return spring, solenoid, and attaching screws. Apply sealing compound at mating surface of solenoid case flange, gear, and drive end housings.
7. Attach motor field terminal to "M" terminal of solenoid and check starter no load current draw.

Exploded View of Motorcraft Starter Motor Assembly Ensure brush holder is in correct position. Scheme 6

SPECIFICATIONS

MOTORCRAFT STARTER SPECIFICATIONS