# 23172729 Thermostat | Genuine Volvo Penta Part

## 🔧 Product Description

Genuine Volvo Penta thermostat from the Cooling System group, weighing 0.077 kg and listed for eight D series engine applications. It supersedes part number 23059851. A thermostat stuck open runs the engine cold; stuck closed it overheats.

## 🚤 Compatibility

Typically suits:

-   Volvo Penta D8A2-A MP
-   Volvo Penta D8A5-A MH
-   Volvo Penta D8A6-A MH
-   Volvo Penta D8A5-A MG
-   Volvo Penta D8A6-A MG
-   Volvo Penta D8A4-A MP
-   Volvo Penta D8A1-A MP
-   Volvo Penta D8A3-A MP

-   **Engine Family:** D

## ⚙️ Key Features

-   0.077 kg
-   Listed for eight D series engine applications
-   Supersedes 23059851
-   From the Cooling System group

## 🔌 Function

Holds coolant flow back until the engine reaches operating temperature, then opens to let it pass to the cooler.

## ⚠️ Common Signs of Failure

-   Engine slow to warm up or never reaching normal temperature
-   Overheating that comes on quickly with the top hose staying cold
-   Temperature gauge swinging up and down instead of holding steady
-   Valve found seized part open, or corroded and furred on removal
-   Coolant weeping at the housing joint

## 🛠️ Service Notes

-   Renew the seal or gasket with the thermostat rather than reusing it
-   Test the old unit in hot water before assuming it was the fault - a blocked cooler or a failing pump gives the same overheating
-   Where the engine takes a pair, renew both together so the two open at the same point

## 🔄 Supersession & Cross Reference

### OEM Supersession Chain

-   23172729 → Supersedes 23059851 → Supersedes 22333526

### OEM / Related Numbers

-   23059851 earlier number superseded by this part
-   22333526 earlier number superseded by this part

## 📦 Condition

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

## Details

- **Price:** 90.11 AUD
- **Vendor:** Volvo Penta
- **Type:** Cooling System
- **Tags:** Volvo Penta

## Variants

| Variant | Price | Available |
|---------|-------|-----------|
| Default Title | 90.11 AUD | In stock |

## Images

- 23172729 Thermostat | Genuine Volvo Penta Part
- 23172729 Thermostat | Genuine Volvo Penta Part - photo 2 of 2

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> Source: [Sawley's Auto and Marine](https://www.sawleysautoandmarine.com.au/products/23172729-thermostat-genuine-volvo-penta)
> Updated: 2026-10-11