Product Specifications
| Parameter | Details |
|---|
| Part Name | Belt Tensioner Assembly |
| Part Number (OEM Reference) | 3936213, 5259022, 3976831 |
| Brand Compatibility | Cummins |
| Engine Model Fitment | 6C, ISB, QSB, 4B3.9, B4.5, 6B5.9, B6.7, 4B, 6B, ISC, QSC, ISL, QSL |
| Condition | New Aftermarket |
| Warranty | 3–12 months against manufacturing defects |
| Packaging | Original sealed box with anti-rust coating and foam protection |
Compatible Models
| Brand | Applicable Models |
|---|
| Cummins | 6C, ISB, QSB, 4B3.9, B4.5, 6B5.9, B6.7, 4B, 6B, ISC, QSC, ISL, QSL |
Tired of Belt Slippage and Engine Overheating? Get the Right Cummins Belt Tensioner Assembly for Your ISB or QSB Engine
Every unscheduled downtime on a construction site costs thousands in lost productivity — especially when caused by a failed belt tensioner. Customers report repeated failures from counterfeit 3936213 belt tensioners, leading to serpentine belt derailment, alternator failure, and engine overheating. OEM replacements take 3–4 weeks and cost up to 45% more, delaying critical maintenance across fleets of excavators, generators, and mobile cranes.
OEM-Equivalent Quality, Ready to Ship from Guangzhou Warehouse
This Cummins belt tensioner assembly is manufactured in ISO 9001-certified facilities and undergoes full-load dynamic testing before shipment — matching OEM torque response and damping characteristics. With 10 years’ experience supplying engine components to repair centers across North America, Africa, and Southeast Asia, we ensure precise fitment for Cummins ISB, QSB, and B6.7 engines used in hydraulic excavators, telehandlers, and off-highway power units.
Where This Part Works
This belt tensioner operates under continuous thermal cycling and high-vibration conditions — typical in mining haul trucks, port container handlers, and demolition excavators. It maintains constant drive-belt tension across temperature ranges from –20°C to +110°C, preventing slippage during peak load cycles in hydraulic pump and air compressor drives. Correct tensioning is essential to avoid premature bearing wear in the alternator and water pump — a key concern for Cummins QSB 6B5.9 belt tensioner assembly applications.
Engineering Details That Matter
The pulley hub is precision-machined from forged SAE 1045 steel with Rockwell hardness HRC 42–46, ensuring resistance to radial impact and fatigue under 150,000+ km service life. Internal damping uses a calibrated hydraulic damper (not spring-only), replicating OEM shock absorption to reduce belt flutter at variable RPM. Sealing meets IP65 standards to resist dust and moisture ingress into the pivot bearing. Dimensional tolerances are held within ±0.05 mm — guaranteeing drop-in replacement without alignment tools or shimming. The zinc-nickel electroplated surface provides 720-hour salt-spray corrosion resistance per ASTM B117.
The Real Cost of Wrong Parts
A $25 substandard tensioner can trigger $2,800 in downstream damage: snapped serpentine belts, seized water pumps, and unplanned engine shutdowns. Industry data shows non-OEM-equivalent tensioners fail 1.7× faster than certified replacements, increasing total cost of ownership (TCO) by 220% over 24 months. This Cummins engine tensioner complies with SAE J1940 and Cummins Engineering Specification CES-11027. Choosing verified aftermarket parts like this 3976831 belt tensioner for Cummins B6.7 avoids warranty voidance and ensures compliance with fleet maintenance protocols.
Why Customers Trust XUNPO
We only partner with ISO 9001-certified factories — every batch undergoes incoming material inspection and dimensional verification. Each Cummins belt tensioner assembly is 100% performance-tested for pivot torque, damping consistency, and pulley runout before shipment. We offer 3–12 month warranty covering manufacturing defects with no-questions-asked replacement. Our 10-year export track record includes shipments to 120+ countries — backed by 20+ in-house technical specialists who verify part compatibility within 2 hours. Over 10,000 SKUs are held in stock at our Guangzhou warehouse, enabling dispatch of in-stock items within 2–5 working days.
Packaging & Shipping
- Individually sealed in rigid cardboard box with molded EPE foam cradle and VCI rust-inhibiting paper
- In-stock items shipped within 2–5 working days after payment 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 until door delivery
- MOQ is 1 piece — designed for urgent field repairs and single-unit validation
Get Your Cummins Belt Tensioner Assembly Now
Your excavator or generator isn’t generating revenue while it’s idle. Send us your part number (e.g., 3936213), engine model (e.g., ISB 6.7), and quantity — we’ll reply with a competitive quote within 24 hours. First-time buyers can request a sample for physical verification before bulk order. No minimum order value. Fast shipping starts the moment you confirm.
Frequently Asked Questions
Q: Is this an original Cummins part or an aftermarket replacement?
A: This is an OEM-equivalent aftermarket belt tensioner assembly, produced in ISO 9001-certified factories to match Cummins engineering specifications and performance standards.
Q: How do I confirm if this belt tensioner fits my machine?
A: Provide your engine model (e.g., QSB 6.7) and equipment application (e.g., John Deere 750K loader). Our technical team verifies compatibility and replies within 2 hours.
Q: What is the warranty period?
A: 3–12 months coverage against manufacturing defects. Defective units are replaced free of charge upon return confirmation.
Q: What is the minimum order quantity?
A: 1 piece — no exceptions. Ideal for emergency repairs, pilot testing, or small fleet maintenance.
Q: How long does shipping take?
A: In-stock items ship within 2–5 working days. Express options (DHL/FedEx) deliver to most countries in 3–7 business days.
Q: Can I receive a sample before placing a bulk order?
A: Yes — first-time customers may request one sample unit for functional and dimensional validation 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
