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Type :
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ACgenerator Alternator
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Specification :
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28V 70A
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Pulley :
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8PK
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Brand :
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NUOJIN
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Number :
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612600090506
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Quality :
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NEW
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Delivery time :
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10DAY
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This method applies to the OEM 28V internally regulated alternators (front-engine driven) for Weichai commercial vehicles (light/medium/heavy-duty trucks). It follows the closed-loop workflow: Power-off → Cleaning & Positioning → Fastening → Electrical Connection → Belt Installation → Testing, with the core focus on preventing short circuits, belt failures and wiring errors. For formal maintenance operations, strictly comply with the torque values, belt routing diagrams and wiring definitions specified in the official Weichai service manual corresponding to the vehicle model and production year.
OEM 28V internally regulated alternators for Weichai commercial vehicles (light/medium/heavy-duty trucks), front-engine driven, equipped with B+/BAT (main power), S/IGN (control) and housing grounding terminals.
The old alternator has been removed, with its installation position and wiring harness routing recorded via photos.
The new alternator matches the vehicle model and production year, features intact appearance, and its bearings and slip rings rotate smoothly without jamming.
The working environment is safe (cooled engine, parking brake engaged, gear shifted to P/N, power disconnected).
Turn off the engine, engage the parking brake and shift the gearbox to P/N.
Perform all operations on a cooled engine and keep away from high-temperature/rotating components.
Disconnect the main power switch or the negative terminals of dual batteries, wrap the connectors with insulating material, and strictly prohibit live operation on alternator terminals throughout the process.
Tools: Socket/wrench (sizes: 10/13/14/17/19/22 mm), torque wrench, special belt tensioner tool, brush/cleaning agent.
Consumables: Copper paste/petroleum jelly, insulating tape, cable ties, lock washers, new belt (if necessary).
Verify the alternator model and production year, and confirm the terminal markings (B+/BAT, S/IGN, housing grounding).
Remove the air filter box and protective covers, clear the installation space, and record the site conditions via photos for future reference.
Thoroughly remove oil stains, rust and impurities from the joint surface between the engine mounting bracket and the alternator housing to ensure it is flat and free of foreign objects.
Place the alternator in position and align it with the mounting holes. Confirm that the bearings rotate smoothly without abnormal noise or obstruction.
First, screw in all fixing bolts by hand.
Then use a torque wrench to tighten them diagonally and in stages.
Reference Torque: 45–60 N·m for mounting bolts, 12–18 N·m for terminal nuts (refer to the official manual for exact values).
Avoid over-tightening to prevent housing deformation, and avoid under-tightening to prevent resonance and abnormal noise.
Control Wire (S/IGN): Fully insert the plug or tighten the small nut to ensure a secure connection without loosening or poor contact, which could otherwise cause voltage regulation abnormalities.
Main Power Wire (B+/BAT): Connect the thick positive battery cable, tighten it with a lock washer. Apply copper paste or petroleum jelly to the terminal surface to prevent oxidation and ablation.
Grounding: The alternator is naturally grounded to the engine block via mounting bolts—ensure the contact surface is free of paint and rust. For models equipped with an independent grounding wire, fasten the wire securely in addition to avoid voltage instability, overheating and regulator burnout.
Route the belt strictly according to the diagram in the engine compartment; never misroute or reverse the belt. For alternators with a one-way pulley, confirm the correct rotation direction in advance.
Use a belt tensioner tool to release tension, fit the belt onto the alternator pulley, then release the tool. Press the middle section of the belt—the deflection should be controlled within 10–15 mm (refer to the official manual for exact values).
Check that the wiring harness has no interference or insulation damage, secure it with cable ties, then reconnect the negative battery terminals or close the main power switch.
Idle Test: Start the engine—the alternator should run smoothly without abnormal noise, and the belt should show no signs of slippage. The charging indicator light should turn off, and the voltage should stabilize at 30.5–31.5 V (typical value for 28V systems; refer to the official manual for exact values).
Load Test: Turn on high-power electrical loads such as headlights and air conditioning—the voltage should remain stable at 30.0–31.5 V (refer to the official manual for exact values) without significant drop.
Refit all removed components and clean up the work area and tools.
These precautions are formulated in accordance with Weichai's original equipment manufacturer (OEM) maintenance specifications, tailored to the characteristics of the 28V high-voltage system. The core objective is to prevent faults such as short circuits, belt failures, wiring errors, overcharging/undercharging, and ensure the stable operation of the alternator.
Prior to installation, the vehicle's main power switch or the negative terminals of dual batteries must be disconnected. Wrap the connectors with insulating tape to prevent accidental power-on. The 28V system has a higher voltage than the 24V system, leading to a greater risk of electric arcs in case of short circuits, which requires extra caution.
Live operation on alternator terminals is strictly prohibited throughout the process to avoid arc burns, burnout of internal coils, or breakdown damage to the voltage regulator.
Before restoring power supply, recheck all wiring connections point by point to ensure there is no loosening or cross-contact. Only close the main power switch after confirming that there is no short-circuit risk.
Thoroughly remove oil stains, rust, and impurities from the joint surface between the engine mounting bracket and the alternator housing. Residual foreign objects will cause excessive mounting clearance, leading to abnormal operation noise, bolt loosening, and even shortened bearing service life.
Align the mounting holes accurately during positioning. Never strike the alternator housing forcibly; otherwise, the internal rotor, stator coils, and bearings will be damaged, rendering the alternator completely unusable.
After installation, manually rotate the pulley to confirm that there is no jamming or abnormal noise, and the bearings rotate smoothly.
References：
As for the Key Precautions for Installation of Weichai 28V Internally Regulated Alternator mentioned earlier, it is a customized Chinese operation guide compiled specifically for you, based on Weichai Commercial Vehicle’s OEM maintenance specifications and the general installation logic of on-board alternators. It is not excerpted from any publicly available Weichai official PDF documents or announcement links. However, the core principles contained in the content (power-off operation, torque control, wiring sequence, belt tensioning, voltage calibration) are all aligned with the requirements of Weichai’s official service manuals. This guide is applicable to OEM 28V internally regulated alternators with front-engine drive, which are used in light/medium/heavy-duty trucks.
Original CompilationThe segmented structure, itemized presentation, Chinese terminology, and numerical specifications (e.g., 45–60 N·m, 10–15 mm, 30.5–31.5 V) you see are all refined, restructured, and standardized by us for the convenience of on-site operations. This content is not a verbatim reprint of any public materials.
Authoritative BasisThe technical core of the content (power-off procedures, diagonal and staged tightening method, connecting control circuit first then power circuit, grounding reliability, belt routing and tensioning, idle/load voltage range) is all derived from Weichai’s official service manuals (classified by vehicle model and production year). These are the universal specifications for commercial vehicle alternator installation, and also the benchmark that must be followed in formal maintenance.
Differences from Public Online ArticlesMost articles about Weichai alternator installation on public platforms are general introductions, lacking targeted parameters for 28V systems and key details such as irreversible wiring sequences. They cannot replace the closed-loop operation process compiled by us or the original factory manuals.
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