# 21686478 Hexagon Nut | Genuine Volvo Penta Part

## 🔧 Product Description

Genuine Volvo Penta hexagon nut weighing 0.025 kg, listed for two TAD series engine applications. The narrow fitment makes this a specific fastener rather than a general-purpose nut, so it should be selected by part number rather than matched by thread alone.

## 🚤 Compatibility

Typically suits:

-   Volvo Penta TAD550GE
-   Volvo Penta TAD551GE

-   **Engine Family:** TAD

## ⚙️ Key Features

-   OEM Volvo Penta part number 21686478
-   Net weight 0.025 kg
-   Listed for two specific engine applications
-   Fits TAD series industrial and marine diesel engines

## 🔌 Function

Provides the threaded clamping element of a bolted joint, holding the assembly at its specified torque. Its grade and dimensions determine the clamping load the joint can carry.

## ⚠️ Common Signs of Failure

-   Rounded or damaged hexagon flats
-   Thread damage, galling or seizing
-   Corrosion making removal difficult
-   Nut repeatedly loosening in service
-   Stretched or distorted after over-tightening

## 🛠️ Service Notes

-   Check the stud or bolt thread is clean and undamaged and run the nut down by hand first; grit on the thread gives a false torque reading
-   Tighten to the torque in the workshop manual for your engine, following the specified sequence on multi-fastener joints and working round in stages so the load comes up evenly
-   Renew self-locking and all-metal locking nuts rather than reusing them — once the locking feature has been through a cycle it no longer holds reliably
-   Fit the washer, tab or locking arrangement that belongs with that joint; a locking device that was bent or crimped in service should be replaced, not straightened and reused
-   Marine-grade anti-seize on stainless threads reduces galling and makes later removal possible, but keep it off threads that must take a locking compound

## 🔄 Supersession & Cross Reference

### Other-Brand OEM Numbers

-   VOE21686478

## 📦 Condition

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

## Details

- **Price:** 10.35 AUD
- **Vendor:** Volvo Penta
- **Type:** Fasteners & Fixings
- **Tags:** Volvo Penta

## Variants

| Variant | Price | Available |
|---------|-------|-----------|
| Default Title | 10.35 AUD | In stock |

## Images

- 21686478 Hexagon Nut | Genuine Volvo Penta Part

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> Source: [Sawley's Auto and Marine](https://www.sawleysautoandmarine.com.au/products/21686478-hexagon-nut-genuine-volvo-penta)
> Updated: 2026-10-08