Installation Process of Weichai 28V Generator (Vehicle Alternator)

I. Pre-installation Preparation and Safety (Top Priority)

1. Vehicle Power Disconnection: Disconnect the negative cable of the battery to prevent short circuits that could burn out the regulator or wire harness.

2. Tools and Accessories: Prepare socket/box-end wrenches, torque wrench, belt tension gauge, new generator, matching drive belt, mounting brackets and bolts (including lock washers), 250–300A fusible links/fuses, ground wires of 10AWG or larger gauge, B+ cables of 6AWG or larger gauge, crimping tool, and thread locker.

3. Data and Model Verification: Confirm that the generator model (e.g., JFZ28 series) matches the engine. Refer to the Weichai Service Manual to obtain mounting bolt torque (typically 18–25 N·m), wiring diagrams, belt models and tension standards.

4. Inspection of Old Unit and Mounting Surface: Clean oil stains and rust from the engine-side mounting surface and brackets; inspect the belt for wear/cracks and check the condition of the tensioner. Replace any damaged components if necessary.

II. Removal of the Old Generator (Reverse Sequence Serves as Installation Benchmark)

1. Remove the Drive Belt: Loosen the generator/auto tensioner, take off the belt and mark its routing direction to avoid reverse installation.

2. Disconnect Electrical Connections: Unplug the regulator connector, remove the B+ terminal cable (insulate the terminal first) and ground wire, and mark the wire harness terminals for identification.

3. Remove Mounting Bolts: Loosen the adjustment bracket bolts first, then the base mounting bolts in sequence. Take off the old generator and its brackets, and check the brackets for deformation or cracks.

III. Installation Steps for the New Generator

1. Cleaning and Positioning

• Clean the mounting surface and brackets; install new brackets if required. Place the new generator into the mounting position and insert the base mounting bolts (do not tighten them temporarily).

• Check the coaxiality of the coupling/pulley to ensure there is no deflection.

2. Belt Installation and Tension Adjustment

• Install the belt according to the marked routing direction. Move the generator to tension the belt and ensure the belt runs without deviation in the pulley grooves.

• Tension Standard: Press the middle of the belt with a finger; the deflection should be approximately 5–8 mm (subject to engine manual specifications). Recheck the tension with a belt tension gauge, then tighten the adjustment bolts and base mounting bolts securely.

3. Bolt Torque Locking

• Tighten the base mounting bolts to the torque specified in the manual (typically 18–25 N·m). Apply thread locker to critical bolts and install lock washers to prevent vibration-induced loosening.

4. Electrical Connections (Sequence Cannot Be Altered)

   Wiring Sequence	Terminal/Wiring	Specification Requirements
   1	Ground Wire	Connect generator housing to engine/body ground point; use wire of 10AWG or larger gauge; tightening torque: 10–12 N·m
   2	Field Wire (IG)	Connect to ignition switch ON position; ensure a continuous 28V power supply; confirm the connector is fully locked
   3	B+ Cable	Use wire of 6AWG or larger gauge; connect generator B+ terminal to battery positive terminal/starter positive terminal; connect a 250–300A fusible link in series; tightening torque: 20–25 N·m
   4	Regulator Connector	Plug in securely and confirm the locking clip is engaged

5. Component Reinstallation: Refit components such as air conditioning hoses and protective covers. Check that the minimum clearance from surrounding parts is ≥ 10 mm to avoid interference risks, then reconnect the battery negative cable.

IV. Commissioning and Verification (Mandatory Steps)

1. Idle Speed Voltage Measurement: Measure the voltage at the B+ terminal; the normal value is 27–29V. At high idle speed, the voltage should remain stable at 28–29.5V.

2. Load Test: Turn on high-load equipment such as headlights and air conditioning. The voltage fluctuation should be ≤ 0.5V without significant drop.

3. Operation Monitoring: After starting the engine, listen for belt squealing or bearing abnormal noise, and observe that the belt runs without deviation or slipping.

4. Insulation and Grounding Check: Measure the insulation resistance between the B+ terminal and generator housing; the value should be ≥ 1MΩ. The grounding resistance should be ≤ 0.1Ω.

5. Installation Precautions for Weichai 28V Generator

6. Power Disconnection Must Be Maintained Throughout the Entire ProcessDisconnect the negative battery cable before installation and keep it disconnected during the entire process to prevent short circuits caused by accidental contact with wire harnesses, which could burn out the generator voltage regulator or the vehicle’s entire electrical system. The negative cable may only be reconnected during the final commissioning and verification phase.
7. Strict Verification of Model and CompatibilityConfirm that the model of the new generator (e.g., JFZ28 series) is fully compatible with the Weichai engine model (e.g., WP6/WP10). Focus on verifying the mounting hole positions, pulley diameter and groove count, and regulator interface definition to avoid faults such as belt misalignment, bolt hole mismatch, and abnormal power generation voltage due to compatibility issues.
8. Bolt Tightening Must Strictly Comply with Torque StandardsTighten the base mounting bolts and adjustment bracket bolts to the torque specified in the Weichai Service Manual (typically 18–25 N·m). Never tighten bolts by brute force. Install lock washers on critical bolts and apply a small amount of thread locker; ensure the thread locker does not come into contact with precision components such as bearings and wiring terminals to prevent corrosion or jamming.
9. Precise Control of Belt TensionAfter installing the belt, the deflection should be controlled within 5–8 mm (measured by pressing the middle of the belt with a finger) or read accurately with a belt tension gauge. Excessively loose tension will cause belt slipping and insufficient power generation; overly tight tension will accelerate wear on the generator bearings and water pump bearings, shortening the service life of the components.
10. Electrical Wiring Must Follow Specifications with No Room for Error

1. Irreversible Wiring Sequence: Always connect the ground wire first, then the field wire (IG), and finally the B+ positive cable. Reversing the sequence may cause circuit breakdown.

2. Compliant Wire and Protection Specifications: The cross-section of the B+ cable shall not be less than 6AWG, and a 250–300A fusible link/fuse must be connected in series. The cross-section of the ground wire shall not be less than 10AWG, and it should be directly connected between the generator housing and the engine/body ground point to ensure the grounding resistance ≤ 0.1Ω.

3. Polarity Must Never Be Reversed: Weichai generators adopt a negative grounding design. It is strictly prohibited to connect the B+ terminal to the negative pole or the housing to the positive pole. Reversing the polarity will instantly burn out the voltage regulator and may even cause a line fire.

   
   

   References：

4. The sources of the Installation Precautions for Weichai 28V Generator are divided into three parts: core authoritative sources, content integration description, and tracing & verification methods, with detailed annotations as follows:

5. I. Core Authoritative Sources (Technical Basis)

6. Weichai Engine Official Service Manual

1. General Chapters: Chapter 414-02 of the Electrical System (Generator and Regulator), Chapter 414-01 (Battery and Cables), and Chapter 303-05 (Accessory Drive Belt). These chapters include installation procedures, base/bracket bolt torque (18–25 N·m), B+ terminal tightening torque (20–25 N·m), wiring diagrams and belt models for mainstream engine models such as WP6 and WP10.

2. Key Requirements: Mandatory requirements including power disconnection operation, wiring sequence, polarity specifications, and clearance inspection are all derived from the safety clauses of the manual.

7. SAE J1455 Automotive Electrical System Installation SpecificationsThis standard covers electrical parameters such as B+ cable gauge (≥6AWG), fusible link capacity (250–300A), ground wire gauge (≥10AWG), and 28V system charging voltage range (27–29V at idle speed, 28–29.5V at high idle speed).
8. Official Technical Documentation for Weichai 28V Generators (e.g., JFZ28 Series)It contains details such as installation benchmarks, belt tension standards (deflection of 5–8 mm), regulator wiring definitions (IG field wire, B+ output terminal), and grounding & insulation requirements (insulation resistance ≥1MΩ, grounding resistance ≤0.1Ω).
9. Industry Universal Standards and Safety SpecificationsWith reference to GB/T 13032 General Technical Conditions for Marine Diesel Generator Sets and QC/T 729 Technical Conditions for Automotive Alternators, supplementary requirements for electrical safety, component clearance (≥10 mm), anti-loosening/insulation protection are added.

10. II. Content Integration Description

11. These precautions are a standardized integration and simplified refinement of the above authoritative materials, rather than a verbatim quotation from a single page. They are designed as a quick installation reference for mainstream Weichai engines.

12. Common risk prompts in practical operation (such as reversed polarity, improper bolt torque, and abnormal belt tension) are supplemented to fully cover the whole process of safety, standardization and fault prevention.