3974102 3973820 Engine Drive Belt Idler Tensioner Pulley For QSL9 QSL8.9

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 3974102 3973820 is engineered for maximum durability and precise fitment in QSL9 QSL8.9 engines. 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: 3974102 3973820

Condition: Brand New / High-Quality OEM / Aftermarket
Warranty: 6 Months / 1 Year
Engine Model: QSL9 QSL8.9

Application:

QSL8.9 (e.g., QSL8.9-C220, QSL8.9-C325, etc.): Widely used in excavators (e.g., R350/375/385), graders, milling machines, loaders, mining equipment, port machinery, and some off-highway dump trucks. Power output ranges from approximately 220–325 horsepower (164–242 kW). It is a Euro III electronically controlled high-pressure common rail engine, commonly found in equipment manufactured between 2007 and 2015.

QSL9: A later or different-caliber version of the QSL8.9 (displacement still 8.9L, inline six-cylinder). Commonly found in medium and large excavators, rotary drilling rigs, bulldozers, and generator sets. Power output is similar (approximately 250–350 horsepower). The "9" suffix in some models may indicate an improved or remanufactured version, but the platform is essentially the same as the QSL8.9.

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