# 3861000 O-Ring | Genuine Volvo Penta Part

## 🔧 Product Description

Genuine Volvo Penta thermostat o-ring weighing 0.002 kg and listed for 92 applications. The accessories catalogue identifies which of the pair it is: it is the large of the two thermostat o-rings on the 8.1Gi, 8.1GXi and 8.1OSi engines, and the small ring in the same housing is 3852071. Size is the whole distinction between them, so order by number rather than trying to match a ring by eye.

## 🚤 Compatibility

-   **Engine Family:** DPX

Full model list at the end of this description.

## ⚙️ Key Features

-   The large thermostat o-ring on the 8.1Gi, 8.1GXi and 8.1OSi engines
-   The small ring in the same housing is 3852071
-   0.002 kg
-   92 listed applications
-   Genuine Volvo Penta Part, designed and manufactured to ensure original fit, safety and performance
-   Role: Thermostat o-ring
-   Fits: 8.1Gi-J/JF, GXi-J/JF, OSi-J/JF (large); 8.1Gi-H/HF, 8.1GXi-G/GF, 8.1OSi-D/DF (large)

## 🔌 Function

Seals a joint by being squeezed into its groove, so the pressure in the circuit holds it tighter rather than pushing it out.

## ⚠️ Common Signs of Failure

-   Weeping or a damp film at the thermostat housing that gets worse when hot
-   Coolant loss with no obvious external leak
-   O-ring flattened, twisted or nibbled on removal
-   Rubber gone hard and taken a permanent set
-   Groove or face pitted where the seal has been leaking

## 🛠️ Service Notes

-   The 8.1 thermostat housing takes both rings, so order 3852071 with it if the whole housing is coming apart
-   Fit dry or lightly lubricated as specified, never stretched over a sharp edge, and check the groove is clean and unpitted first
-   Always refer to the operator's manual for the recommended maintenance and service intervals for your engine and drive
-   Listed against more than one engine or drive family - check the qualifier that applies to your own engine or drive

## 📦 Condition

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

## 🔎 Full Model Compatibility

Typically suits:

-   Volvo Penta 8.1Gi-B, 8.1Gi-BF, 8.1Gi-C, 8.1Gi-CF, 8.1GiC-J, 8.1GiC-JF, 8.1GiCE-JF, 8.1GiCE-J, 8.1GiCE-M, 8.1GiCE-P, 8.1GiC-Q, 8.1GiCE-Q, 8.1Gi-D, 8.1Gi-DF, 8.1Gi-E, 8.1Gi-EF, 8.1GiE-JF, 8.1GiE-J, 8.1GiE-KF, 8.1GiE-K, 8.1GiE-M, 8.1GiE-MF, 8.1GiE-P, 8.1Gi-F, 8.1Gi-FF, 8.1Gi-G, 8.1Gi-GF, 8.1Gi-H, 8.1Gi-HF, 8.1GiI-A, 8.1GiI-B, 8.1GiI-C, 8.1GiI-D, 8.1GiI-E, 8.1GiI-F, 8.1GiI-G, 8.1GiI-H, 8.1Gi-J, 8.1Gi-JF, 8.1GSi-A, 8.1GSiI-A, 8.1GXi-A, 8.1GXi-AF, 8.1GXi-B, 8.1GXi-BF, 8.1GXi-C, 8.1GXi-CF, 8.1GXi-D, 8.1GXi-DF, 8.1GXi-E, 8.1GXi-EF, 8.1GXiE-JF, 8.1GXiE-J, 8.1GXiE-K, 8.1GXiE-KF, 8.1GXiE-M, 8.1GXiE-P, 8.1GXi-F, 8.1GXi-FF, 8.1GXi-G, 8.1GXi-GF, 8.1GXiI-A, 8.1GXiI-B, 8.1GXiI-C, 8.1GXiI-D, 8.1GXiI-E, 8.1GXiI-F, 8.1GXiI-G, 8.1GXi-J, 8.1GXi-JF, 8.1IPSE-KF, 8.1OSi-A, 8.1OSi-AF, 8.1OSi-B, 8.1OSi-BF, 8.1OSi-C, 8.1OSi-CF, 8.1OSi-D, 8.1OSi-DF, 8.1OSi-J, 8.1OSi-JF, 8.1OSiE-JF, 8.1OSiE-J
-   Volvo Penta DPX420-CF, DPX420-DF, DPX420-A, DPX420-B, DPX420-BF
-   Volvo Penta DPX375-A, DPX375-B, DPX375-BF, DPX375-CF

## Details

- **Price:** 10.47 AUD
- **Vendor:** Volvo Penta
- **Tags:** Volvo Penta

## Variants

| Variant | Price | Available |
|---------|-------|-----------|
| Default Title | 10.47 AUD | In stock |

## Images

- 3861000 O-Ring | Genuine Volvo Penta Part

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> Source: [Sawley's Auto and Marine](https://www.sawleysautoandmarine.com.au/products/3861000-o-ring-genuine-volvo-penta)
> Updated: 2026-08-22