# 21615589 Cap | Genuine Volvo Penta Part

## 🔧 Product Description

A pressure-rated filler cap used on the closed-cooling expansion tank of Volvo Penta V8 petrol marine engines.

## 🚤 Compatibility

Typically suits:

-   Volvo Penta 3.0GXiC-J
-   Volvo Penta 3.0GXi-J

## ⚙️ Key Features

-   Closed-cooling pressure cap
-   Seals expansion tank 21614836
-   Controls cooling-system pressure and venting
-   Heat- and coolant-resistant sealing element
-   Correct filler-neck engagement

## 🔌 Function

The cap seals the tank and maintains the specified pressure so coolant boiling point and recovery operation remain controlled.

## ⚠️ Common Signs of Failure

-   Coolant leaking around the cap
-   Pressure not retained
-   Hardened or damaged seal
-   Cap difficult to lock or remove
-   Repeated coolant discharge at normal temperature

## 🛠️ Service Notes

-   Clean and inspect the seating face on the housing as well as the cap — most leaks past a cap are the seat or the seal rather than the cap body
-   Renew any separate O-ring or gasket that goes with the cap, and lubricate rubber seals lightly with clean oil or grease so they slide home instead of rolling or tearing
-   Do not over-tighten a cap into a plastic or aluminium housing; it seals on its gasket or O-ring, not on force, and stripped threads mean a much bigger repair
-   Where a cap blanks a port during a repair, keep it fitted right up to the moment of assembly so nothing enters the opening
-   Check the cap is fully home and that any retaining clip, lanyard or locking tab is secure before returning the boat to service

## 🔄 Supersession & Cross Reference

### OEM / Related Numbers

-   21614836 - Expansion tank
-   21614847 - Cover
-   21614855 - Bracket
-   21614860 - Spill plate

## 📦 Condition

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

## Details

- **Price:** 221.0 AUD
- **Vendor:** Volvo Penta
- **Type:** Cooling System
- **Tags:** Volvo Penta

## Variants

| Variant | Price | Available |
|---------|-------|-----------|
| Default Title | 221.00 AUD | In stock |

## Images

- 21615589 Cap | Genuine Volvo Penta Part

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> Source: [Sawley's Auto and Marine](https://www.sawleysautoandmarine.com.au/products/21615589-cap-genuine-volvo-penta)
> Updated: 2026-10-09