Belt tensioner pulley for Cummins 4BT, 6BT diesel engines, aftermarket automatic tensioning component that maintains proper drive belt tension for alternator, water pump and fan assembly. All part numbers are cross-referenced against OEM specs for direct matching.

Part numbers: 5333477, 3937553, 3914086, 3917485, 3922900, 3934818, 3936201, 3964636, 3978022
Fits: Cummins 4BT, 6BT diesel engine
Position: Engine accessory drive belt system

What you are ordering
Price is per belt tensioner pulley. All part numbers are separate variants, please select the correct PN from variant options. These tensioners are not interchangeable. Different part numbers have different spring tension, pulley diameter and mounting hole layout. Wrong selection will lead to loose belt, belt slippage and early belt failure.

Specifications
Material: cast iron housing + bearing steel pulley
Structure: spring loaded automatic tension assembly
Bearing & tension rating: calibrated to OEM standard
Finish: anti-corrosion coating, pre-greased bearing, rotation tested before packing
Packing: individual protective box, marked with part number

When to replace
Replace the tensioner pulley when bearing is noisy, pulley wobbles, spring loses tension or surface is cracked. Common failure signs: squealing belt noise, belt skipping, over-tension or insufficient tension. Replace the tensioner together with drive belt during maintenance.

Fitting notes
Strictly confirm engine serial number before ordering. Do not install tensioners of different part numbers interchangeably. Follow Cummins service manual for belt routing and tension check. If you are not sure which PN matches your engine, send us engine serial number for confirmation.

Warranty and shipping
Covered by a 12-month warranty against manufacturing defects. Orders are dispatched within 3–7 business days; DHL / FedEx delivery takes 5–10 business days. Tracking number is sent as soon as the parcel leaves our warehouse.

Note: manufacturer names and part numbers are used for identification and cross-referencing only. We are an independent aftermarket supplier and are not affiliated with, or authorised by, the original manufacturer. Please verify the part number against your engine's parts catalogue before ordering — our team is happy to help if you send us your engine model or serial number.