21280913 Idler Pulley | Genuine Volvo Penta Part

🔧 Product Description

Genuine Volvo Penta belt idler pulley for specified early D4 and D6 marine engines. It supersedes pulley 3848896 and applies only up to the stated engine serial numbers, after which a revised belt-drive arrangement may be used.

🚤 Compatibility

• Engine Family: D
• HP Range: 260-435 HP
• Serial Range: SN-2006032252

Full model list at the end of this description.

⚙️ Key Features

• Genuine Volvo Penta belt idler pulley
• Supersedes 3848896
• D4 fitment through engine serial 2006032252
• D6 fitment through engine serial 2006032252
• Sealed bearing and correct belt-running profile
• Engine type: Volvo Penta D4 inline-four or D6 inline-six common-rail marine diesel

🔌 Function

Guides and stabilises the accessory belt so it tracks correctly and maintains the designed wrap around driven pulleys.

⚠️ Common Signs of Failure

• Bearing rumble, chirp or grinding noise
• Visible wobble or pulley misalignment
• Belt tracking off-centre or producing dust
• Seized or rough pulley rotation
• Cracks, damaged grooves or excessive free play

🛠️ Service Notes

• Spin the new pulley by hand before fitting — it should turn smoothly and quietly with no roughness, no drag and no side play
• Inspect the belt-contact face of every pulley in the drive whenever the idler is changed; a grooved, glazed, corroded or chipped face will ruin a new belt quickly
• Renew the belt at the same time, and check the tensioner as well, since these parts wear as a system
• Tighten the mounting fastener to the figure given in the workshop manual for your engine, and confirm the pulley runs true and in line with the rest of the drive
• Check the belt routing and that every rib or groove is properly seated before turning the engine over, then recheck tension after the first running period as the manual directs

🔄 Supersession & Cross Reference

OEM Supersession Chain

• 21280913 → Supersedes 21172053 → Supersedes 3848896 → Supersedes 3883786

OEM / Related Numbers

• 3848896 earlier number superseded by this part
• 21172053 earlier number superseded by this part

Aftermarket / Verified Equivalents

• FridayParts: replacement for 21280913 / 3848896

📦 Condition

• Genuine Volvo Penta part
• Brand new
• Supplied in original or equivalent packaging

🔎 Full Model Compatibility

Typically suits:

• Volvo Penta D6-370A-C, D6-350A-A, D6-350A-B, D6-370D-E, D6-370D-B, D6-370A-F, D6-370D-A, D6-370D-C, D6-370D-D, D6-370A-D, D6-370A-E, D6-370D-F, D6-435I-D, D6-400A-E, D6-435D-A, D6-435D-D, D6-435D-E, D6-435I-A, D6-435I-C, D6-435I-E, D6-435D-C, D6-370A-B
• Volvo Penta D4-260A-B, D4-260A-A, D4-260A-C, D4-260A-D, D4-260A-E, D4-260D-B, D4-260D-C, D4-260D-D, D4-260D-E, D4-300A-A, D4-300A-C, D4-300A-D, D4-300A-E, D4-300D-A, D4-300D-C, D4-300D-D, D4-300D-E