# 21860003 Idler Gear | Genuine Volvo Penta Part

## 🔧 Product Description

A genuine timing-gear idler used in the engine gear train on Volvo Penta D8 and selected TAD5 engines. It transfers rotation between the crankshaft, camshaft and auxiliary gears.

## 🚤 Compatibility

-   **Engine Family:** TAD, D, TADH
-   **HP Range:** Approximately 225-650 HP
-   **Year Range:** Approximately 2010 - current supported applications

Full model list at the end of this description.

## ⚙️ Key Features

-   Timing-gear idler for the engine gear train
-   0.581 kg
-   Listed for 26 applications across the TAD, D and TADH ranges
-   Transfers rotation between the crankshaft, camshaft and auxiliary gears

## 🔌 Function

Sits between the driving and driven gears in the timing train, passing rotation across the gap and holding the timing relationship between crankshaft, camshaft and the auxiliary drives.

## ⚠️ Common Signs of Failure

-   Whine or growl from the timing end that rises with engine speed
-   Rattle at idle that quietens as revs come up
-   Metallic glitter in the oil or on the drain plug
-   Teeth pitted, chipped or with a wear step across the face on strip-down
-   Bearing or bush worn, giving perceptible rock on the shaft

## 🛠️ Service Notes

-   Idler gear 21860076 is the heavier gear in the same train at 1.844 kg - check which position is being replaced before ordering
-   Inspect the mating gears and the idler shaft at the same time; a failed idler leaves its wear pattern on both
-   Renew the bush or bearing hardware with the gear where the assembly is built that way

## 🔄 Supersession & Cross Reference

### OEM / Related Numbers

-   21736275 - idler-gear hub
-   976042 - O-ring
-   21736279 - retaining plate
-   964106 - gasket
-   21735434 - related drive gear

## 📦 Condition

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

## 🔎 Full Model Compatibility

Typically suits:

-   Volvo Penta D8A2-A MP, D8A5-A MH, D8A6-A MH, D8A5-A MG, D8A6-A MG, D8A4-A MP, D8A1-A MP, D8A3-A MP
-   Volvo Penta TAD840GE, TAD840-43VE, TAD840GE-B
-   Volvo Penta TAD570-72VE, TAD570-71VE-B
-   Volvo Penta TAD880-82GE, TAD880-84VE
-   Volvo Penta TADH880-82GE, TADH880-84VE
-   Volvo Penta TAD540-42VE
-   Volvo Penta TAD550-51VE
-   Volvo Penta TAD552VE
-   Volvo Penta TAD580-83VE
-   Volvo Penta TAD841-43GE
-   Volvo Penta TAD850-52VE
-   Volvo Penta TAD851-53GE
-   Volvo Penta TAD853VE
-   Volvo Penta TAD870-73VE

## Details

- **Price:** 414.29 AUD
- **Vendor:** Volvo Penta
- **Type:** Engine Components
- **Tags:** Volvo Penta

## Variants

| Variant | Price | Available |
|---------|-------|-----------|
| Default Title | 414.29 AUD | In stock |

## Images

- 21860003 Idler Gear | Genuine Volvo Penta Part
- 21860003 Idler Gear | Genuine Volvo Penta Part - photo 2 of 2

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> Source: [Sawley's Auto and Marine](https://www.sawleysautoandmarine.com.au/products/21860003-idler-gear-genuine-volvo-penta)
> Updated: 2026-10-09