Product Specifications
| Parameter | Details |
|---|
| Part Name | Belt Tensioner |
| Part Number (OEM Reference) | 3976832, 3911621, 3937556, 3936207, 3934823, 3922901, 3973825, 3936208, 3934824, 3928748, 3279446, 4063951 |
| Brand Compatibility | Cummins, Hyundai |
| Machine Model Fitment | Hyundai R305LC-7, R290LC-7, R290LC-3, R250LC-7, HL757-7, HL740-9B, HL740-9S, HL760, HL740-3, HL740TM-3, HL750TM, HL720-3C, HL730-3, HL730TM-3, HL7303C, HL730TM3C, HL740-3ATM, HL740TM-3A, 42HDLL, 39HDRB, HDF35AII, HDF45AII; M939, M939A1, M939A2, M923, M931, M936, M925 series |
| Engine Fitment | Cummins 4B3.9, 6B5.9, 6C8.3, B5.9 G, B5.9 LPG PLUS CM556, C8.3 G, ISB (Chrysler), ISB CM550, QSB5.9 CM550, QSB5.9 CM850, 4BT3.9, 6BT5.9, ISB3.9, ISB4.5, QSB3.9, 6C, 6CT, 6CTA, 6CTAA, C8.3L |
| Condition | New Aftermarket |
| Warranty | 3–12 months against manufacturing defects |
| Packaging | Original box with anti-static foam and reinforced corrugated carton |
Compatible Models
| Brand | Applicable Models |
|---|
| Hyundai | R305LC-7, R290LC-7, R290LC-3, R250LC-7, HL757-7, HL740-9B, HL740-9S, HL760, HL740-3, HL740TM-3, HL750TM, HL720-3C, HL730-3, HL730TM-3, HL7303C, HL730TM3C, HL740-3ATM, HL740TM-3A, 42HDLL, 39HDRB, HDF35AII, HDF45AII |
| Military Vehicles | M939, M939A1, M939A2, M923, M931, M936, M925 |
Tired of Serpentine Belt Slippage and Engine Overheating? Get the Right Belt Tensioner 3976832 for Your Cummins 4B3.9 or Hyundai R305LC-7
Every unplanned engine shutdown on a construction site costs thousands in labor, rental, and delay penalties. Operators report repeated belt slippage, squealing noises, and premature alternator failure — often traced to worn or underspec tensioners. OEM replacements take 3–4 weeks and cost up to 45% more. Worse, counterfeit tensioners lack proper spring preload calibration and fail within 200 operating hours.
OEM-Equivalent Quality, Ready to Ship from Guangzhou Warehouse
This belt tensioner is manufactured in ISO 9001-certified factories with full traceability. Each unit undergoes dynamic load testing at 120% rated tension force before shipment — matching Cummins QSB5.9 serpentine belt system specifications. Designed for continuous-duty applications like excavation, quarrying, and port material handling, it maintains consistent belt engagement during high-vibration operation and rapid throttle transitions.
Where This Part Works
You’ll find this tensioner installed on heavy equipment operating in extreme conditions: mining haul trucks idling under load, hydraulic excavators performing repetitive digging cycles, and military logistics vehicles running 16-hour shifts on unpaved terrain. In these environments, inconsistent belt tension causes voltage drops, overheating, and cascading failures in cooling and charging systems — making precise tension control mission-critical.
Engineering Details That Matter
The housing is precision die-cast aluminum alloy (A380) with T6 heat treatment for dimensional stability under thermal cycling. The pivot shaft uses hardened 42CrMo steel (HRC 48–52) with micro-ground bearing surfaces to minimize friction loss and prevent galling. Internal torsion spring is made from ASTM A228 music wire, pre-stressed and fatigue-tested to 500,000 cycles at operating temperature. Mounting bolt holes are CNC-machined to ±0.05 mm tolerance for perfect alignment with OEM brackets. Surface finish includes chromate conversion coating (MIL-DTL-5541 Class 3) for corrosion resistance in humid and salt-laden environments.
The Real Cost of Wrong Parts
A $48 counterfeit tensioner may save $25 upfront — but leads to $1,200 in belt and pulley replacement, $380 in labor, and $4,500+ in downtime per incident. Independent field data shows non-OEM-equivalent units reduce average service life by 62% versus certified parts. This tensioner meets SAE J2044 and ISO 10002 standards for rotating accessory drive systems. Total cost of ownership drops when you factor in 3–12 month warranty coverage, zero rework, and predictable uptime — not just unit price.
Why Customers Trust XUNPO
Only ISO 9001-certified factories supply our belt tensioners — all raw materials inspected upon receipt. Every unit undergoes functional performance testing at 120% rated load before packing. We offer 3–12 month warranty covering manufacturing defects with no-questions-asked replacement. With 10 years of export experience, we’ve shipped over 240,000 engine components to 120+ countries. Our 20+ technical staff verify part compatibility using OEM service manuals and real machine teardown data — responses delivered within 2 hours. Over 10,000 SKUs are held in stock at our Guangzhou warehouse for same-day dispatch.
Packaging & Shipping
- Individually boxed with custom-cut EPE foam and sealed in double-wall corrugated cartons (dimensions: 180 × 120 × 80 mm)
- In-stock items ship within 2–5 working days after order confirmation
- Flexible logistics: DHL/FedEx/UPS express (3–7 days), air freight (7–12 days), or sea freight (25–40 days)
- Real-time tracking number provided upon dispatch, updated daily until delivery
- MOQ is 1 piece — supports urgent field repairs and small fleet operators
Get Your Belt Tensioner 3976832 or 3911621 Today
Your excavator or generator set isn’t generating revenue while waiting for parts. Send us your machine model (e.g., Hyundai R305LC-7), engine type (e.g., Cummins QSB5.9), and required quantity — we’ll email a competitive quote within 24 hours. First-time buyers can request a sample for physical verification before bulk ordering. All in-stock orders ship from Guangzhou within 2 business days.
Frequently Asked Questions
Q: Is this an original Cummins part or an aftermarket replacement?
A: This is an OEM-equivalent aftermarket belt tensioner, manufactured in ISO 9001-certified facilities to meet Cummins 3976832 and 3911621 dimensional, material, and performance specifications.
Q: How do I confirm if this fits my specific machine?
A: Provide your exact machine model (e.g., R290LC-3), engine serial prefix (if known), and current tensioner part number — our technical team confirms compatibility within 2 hours using OEM service documentation.
Q: What is your warranty policy?
A: 3–12 months warranty against manufacturing defects. If failure occurs due to material or workmanship, we replace the part at no cost — no restocking fee.
Q: What is the minimum order quantity?
A: 1 piece. We support emergency maintenance needs with no volume requirement.
Q: How fast can you ship?
A: In-stock items ship within 2–5 working days. Express courier options (DHL/FedEx) deliver to most destinations in 3–7 days.
Q: Can I receive a sample before placing a bulk order?
A: Yes. First-time customers may request one sample for physical inspection and fitment verification prior to bulk purchase.
Ready to order or need a quote?
Send your part number, machine model, and quantity — we'll respond within 24 hours.
WhatsApp: +86 13316055942 | Email: talos@xunpojx.com
