3976834 4984045 Engine V-ribbed Belt Tensioner Pulley For B3.9L 4BT 6BT 5.9L 6B

Product Specification

A belt tensioner is a device that applies a predetermined amount of tension to the engine's accessory drive belt (serpentine belt). Its primary function is to maintain constant, optimal tension on the belt as it wears and stretches over time. This prevents the belt from slipping, squealing, or throwing off, ensuring that critical components like the alternator, water pump, and A/C compressor operate reliably. This belt tensioner 3976834 4984045 is engineered for maximum durability and precise fitment in B3.9L 4BT 6BT 5.9L 6B 6BTA 4BT 4BTA 6D107 QSB6.7 Engine. Manufactured to meet or exceed OEM standards, it ensures optimal engine performance and a long service life under heavy-duty conditions.

Whether for full engine rebuilds or quick replacements, DDP Engine provides you with the most reliable parts at unbeatable wholesale prices.

Parameter Details
Product Name: Belt Tensioner
Part Number: 3976834 4984045 

Condition: Brand New / High-Quality OEM / Aftermarket
Warranty: 6 Months / 1 Year
Engine Model: B3.9L 4BT 6BT 5.9L 6B 6BTA 4BT 4BTA 6D107 QSB6.7

Application:

4BT / 4BTA (3.9L inline 4-cylinder): Light commercial vehicles, construction vehicles (such as mini excavators and forklifts), generator sets, and agricultural machinery; "T" stands for turbocharged, and "A" stands for intercooled. 4BTA power output is approximately 90–125 kW (120–170 hp).

6BT / 6BTA (5.9L inline 6-cylinder): Medium and heavy-duty trucks, buses, construction machinery (loaders, bulldozers), and marine auxiliary power; 6BTA (turbocharged and intercooled) power output can reach 130–170 kW (180–230 hp), commonly found in 1990s–2000s models. B3.9L (3.9L inline 4-cylinder, not "BT" series): For non-road machinery (such as forklifts, generators, pump stations), it belongs to the basic naturally aspirated or turbocharged version of the B series, with a power output of 80–110 kW; note that "B3.9L" is not a standard designation, usually referring to the 3.9L model of the B series (such as B140).

5.9L / 6B (no "T/A" suffix): Early naturally aspirated trucks/stationary power units, mostly products from the 1980s–1990s, with lower power output (approximately 80–110 kW), and have been largely replaced by 6BT/6BTA.

6D107: Used in heavy trucks, ships, and construction machinery.

QSB6.7 (6.7L inline 6-cylinder, Common Rail): Medium and heavy-duty trucks, construction machinery (excavators, road rollers), generator sets, electronically controlled common rail, power 130–220 kW (180–300 hp), meets China IV/China V emission standards.

Why Choose DDP Engine:
100% Quality Guaranteed: All parts undergo rigorous testing to ensure perfect compatibility and premium performance.
Fast Worldwide Shipping: Large inventory in stock. Orders are typically processed within 3-7 working days with reliable global express and Transportation.
Professional Technical Support: Unsure about the part number? Contact our engineering team for exact cross-reference matching.
Flexible Solutions: Providing Genuine, OEM, and premium Aftermarket spare parts to fit your budget.