Mitsubishi S4S Engine 12V 2.2kW Starter Motor - Installation Method & Core Precautions

I. Pre-installation Preparation (Mandatory Steps)

Power Off for Safety

Component Cleaning

Accessory Verification

Tool Preparation

II. Standardized Installation Method (Step-by-Step Operation)

Step 1: Initial Positioning of the Starter Motor

Step 2: Pre-tighten the Mounting Bolts

Step 3: Drive Gear Clearance Check (Critical)

Step 4: Torque Tightening of Mounting Bolts

Step 5: Wiring Terminal Connection

1. Thick terminal (B+) connection: Put on copper gaskets (double-sided gaskets), connect to the positive cable of the battery, and tighten the nut with a torque of 25~30N·m. Wrap the terminal with insulating tape (to prevent grounding).

2. Thin terminal (S) connection: Connect to the control plug of the engine wiring harness (the plug is designed with anti-reverse insertion and cannot be inserted reversely), tighten the fixing screw (hand-tighten only, no torque required) and ensure the plug is free of looseness.

3. After all wiring is completed, check that the terminals are not in contact with the starter motor housing (to prevent short circuit), and reserve sufficient movement for the wiring harness (to avoid harness pulling due to engine vibration).

Step 6: Battery Reset

Step 7: No-Load Test Run (Post-installation Verification)

III. Core Precautions (By Category, Including Fault Avoidance)

(1) Installation Process Precautions (Mandatory Original Factory Requirements)

1. Bolts and Torque: Grade 8.8 or higher high-strength bolts must be used; replacement with ordinary bolts is prohibited. Strictly follow the torque of 55~60N·m. Over-tightening will cause damage to the flywheel housing threads, while under-tightening will lead to bolt looseness and starter motor falling off due to engine vibration.

2. Positioning and Clearance: Locating pins must be fully inserted into the holes; for models without locating pins, ensure no radial offset of the starter motor after installation. The meshing clearance between the drive gear and the flywheel ring gear must not exceed 0.5~1.5mm. Excessively small clearance will cause gear jamming, and excessively large clearance will result in insufficient meshing and tooth chipping.

3. Wiring Specifications: Copper gaskets must be added to the thick terminal to prevent high-temperature ablation of the terminal due to poor contact of large current. Reverse insertion of the thin terminal plug will cause the electromagnetic switch to fail to work and even burn the wiring harness. After all wiring is completed, arrange the wiring harness and keep it away from high-temperature engine components (e.g., exhaust manifold).

4. Lubrication Requirements: Apply a small amount of high-temperature resistant lithium-based grease to the tooth surface and bearing of the starter motor drive gear (apply before installation); excessive application is prohibited (to prevent adhesion to the flywheel ring gear). No grease is allowed on the flange surface (to avoid sealing damage and easy oil contamination).

(2) Safe Operation Precautions

1. Short circuit between the positive and negative poles of the battery is prohibited throughout the process. Avoid simultaneous contact of tools (e.g., socket wrenches, spanners) with the positive and negative terminals during installation.

2. During the test run, the operator must stay away from rotating components such as the engine flywheel and pulley, and it is forbidden to touch the drive gear by hand.

3. If thread slipping of the flywheel housing is found during installation, repair it with a thread repair insert (wire thread insert); direct enlargement of the bolt size is prohibited.

I. Core Authoritative Sources (Original Factory Service Manuals)

• Version: October 2004 (Publicly available PDF, including chapters on electrical system/starter motor)

• Version: 99616-87100 (2012 edition, 190 pages, including Chapter 12 Electrical System covering starter motor installation, torque values, clearance specifications and wiring criteria)

• Content Source: Extracts from the sections of Starter Removal & Installation, Service Data and Electrical System in the manual, including:

• Mounting bolt specifications (M12×1.75, Grade 8.8) and torque value (55–60N·m)

• Meshing clearance between drive gear and flywheel ring gear (0.5–1.5mm)

• Wiring terminal torque values (25–30N·m for B+ terminal, 18–22N·m for ground terminal)

• Key requirements for safe operation, clearance adjustment and fault troubleshooting

• Application: Exclusive for S4S diesel engines (including derivative models such as S4S-DT); the 12V 2.2kW starter motor is the standard original factory configuration.

• Rated voltage (12V), power (2.2kW) and number of drive gear teeth (10 teeth)

• Definitions of mounting flange, locating pins and wiring terminals

• Pull-in/release voltage of the electromagnetic switch and stroke parameters of the drive gear

II. General Industry Standards (Supplementary Basis)