# 20405986 Cap Plug | Genuine Volvo Penta Part

## 🔧 Product Description

Genuine Volvo Penta cap plug installed in the D5A / D7A cylinder block. One plug is used to close a manufacturing or service opening near the piston-cooling jet and main oil-gallery hardware.

## 🚤 Compatibility

Typically suits:

-   Volvo Penta D5A-B TA
-   Volvo Penta D5A-T
-   Volvo Penta D5A-TA
-   Volvo Penta D7A-B TA
-   Volvo Penta D7A-T
-   Volvo Penta D7A-TA
-   Volvo Penta D7C-B TA
-   Volvo Penta D7C-TA
-   Volvo Penta TAD750GE
-   Volvo Penta TAD751GE
-   Volvo Penta TAD750VE
-   Volvo Penta TAD760VE
-   Volvo Penta MD2010
-   Volvo Penta MD2010B

-   **Engine Family:** D, TAD, MD

## ⚙️ Key Features

-   Cylinder-block gallery cap plug
-   One used on four- and six-cylinder D5A / D7A blocks
-   Located beside the piston-cooling jet and block gallery components
-   Provides a permanent or serviceable closure for the machined bore
-   Must be fitted using the specified installation and sealing method
-   Engine type: Volvo Penta four- and six-cylinder industrial diesel

## 🔌 Function

Closes a machined cylinder-block passage to retain oil or coolant and prevent contamination.

## ⚠️ Common Signs of Failure

-   Oil or coolant seepage around the plug
-   Plug movement or corrosion
-   Pressure loss in the associated gallery
-   Damaged cylinder-block bore
-   Leak recurring after incorrect plug installation

## 🛠️ Service Notes

-   Fit a new plug rather than refitting a used one — a plug that has been driven or screwed out will not seal reliably a second time
-   Clean the bore or threads out fully and check the sealing seat for corrosion pitting and damage; a pitted seat will keep weeping whatever plug is fitted
-   Fit the plug squarely and to the depth or tightness given in the workshop manual for your engine, using only the sealant or thread compound specified for that joint
-   Support the surrounding casting where you can and drive or tighten without distorting the plug, then pressure test or run the engine up and check the plug for weeping

## 🔄 Supersession & Cross Reference

### OEM / Related Numbers

-   20405561 - piston-cooling jets
-   20405728 - related sealing ring
-   20405716 - related threaded block plugs
-   20508600 - related threaded block plugs
-   21039801 - configuration-dependent cap plugs
-   20758137 - configuration-dependent cap plugs
-   966871 - related shut-off cock on D7A blocks

## 📦 Condition

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

## Details

- **Price:** 12.65 AUD
- **Vendor:** Volvo Penta
- **Type:** Fasteners & Fixings
- **Tags:** Volvo Penta

## Variants

| Variant | Price | Available |
|---------|-------|-----------|
| Default Title | 12.65 AUD | In stock |

## Images

- 20405986 Cap Plug | Genuine Volvo Penta Part

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> Source: [Sawley's Auto and Marine](https://www.sawleysautoandmarine.com.au/products/20405986-cap-plug-genuine-volvo-penta)
> Updated: 2026-09-18