VolvoEngine Parts

20739751 Alternator Belt Tensioner — Volvo FM9 FM11

This is an alternator belt tensioner, a crucial component in the engine's accessory drive system for Volvo trucks. It automatically maintains the correct tension on the alternator belt, ensuring efficient power transfer to the alternator and other accessories. A worn or seized tensioner can lead to a loose belt, causing the alternator to undercharge the battery, or a broken belt, resulting in a loss of power steering and other critical functions. Operators may notice a squealing noise from the belt or a battery warning light.

Alternator Belt Tensioner – Part No 20739751 – Volvo Spare Part
Part Specifications
BrandVolvo
CategoryEngine Parts
ConditionAftermarket — OEM Specification
DispatchSame-day from Mumbai (before 3 PM IST)
GST InvoiceAvailable — all orders
Export DocsCommercial invoice, packing list, COO

Compatible Models

Always verify with serial number before ordering.

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Cross References & OEM Numbers

Alternate part numbers that interchange with Volvo 20739751

Fitment: Volvo Trucks: FH13: 2006> 2012 FM7: 1999> 2001 FM9: 2002;2007 FM11: 2009; FM13:2006> 2012 FMX, Renault Trucks: Premium II TR/PR, Kerax /DXi11/13, Magnum DXi13, Vo

Installation & Application Notes

Inspect mating surfaces for wear before fitting. Use torque specs from service manual. Replace gaskets and seals as a set — reusing compressed gaskets causes oil leaks. Clean all oil passages with compressed air.

Always consult the OEM service manual for model-specific torque values and procedures. WhatsApp our technical team if you need fitment guidance.

Part TypeAlternator Belt Tensioner
MaterialSteel, rubber
ApplicationEngine accessory drive system
Service LifeReplace as needed based on inspection and noise
CompatibilityVolvo FH13, FM7, FM9, FM11, FM13, FMX; Renault Premium II, Kerax
ConditionNew — OEM specification aftermarket

Failure Symptoms

A failing belt tensioner will often first produce an audible squealing or chirping sound from the engine bay, especially during startup or acceleration. If the tensioner fails completely, the belt can become loose, leading to a loss of charging from the alternator and potential overheating if it also drives the water pump. The ultimate consequence is a breakdown due to a dead battery or loss of essential power steering.

Installation Tip

When releasing tension on the old unit, be careful not to let the tensioner arm snap back suddenly, as this can cause injury or damage. Ensure the new tensioner is fully seated and aligned correctly before applying tension to the new belt.

Service Note

When replacing the alternator belt tensioner, always inspect the condition of the alternator belt itself for signs of wear, cracking, or glazing, and replace it if necessary.