# 23370774 Gear Housing Kit | Genuine Volvo Penta Part

## 🔧 Product Description

A genuine Volvo Penta complete ratio-specific lower gear assembly for selected MS25S and MS25SR saildrives. The reduction is commonly listed as 2.47:1 and may be rounded to 2.5:1 in some parts catalogues.

## ⚙️ Key Features

-   Complete genuine Volvo Penta lower gear unit
-   Nominal 2.47:1 reduction ratio
-   MS25S and MS25SR saildrive application
-   Factory-aligned gear and bearing assembly
-   Supersedes earlier lower gear 3817154
-   Engine type: Volvo Penta MS25S / MS25SR saildrive lower gear housing
-   Also supersedes Volvo part numbers 3812349, 3856833, 851646, 853555 and 873090

## 📋 Kit Contents

-   1 x complete assembled lower gear housing / lower gear unit - Volvo Penta 23370774
-   Ratio-specific vertical shaft, propeller shaft, bevel gears, bearings and internal seals are integral to complete assembly 23370774
-   Internal components are supplied as part of the complete ratio-specific assembly and are not separately itemised under this kit

## 🔌 Function

The assembly reduces input speed and redirects torque through the lower bevel gears to the propeller shaft.

## ⚠️ Common Signs of Failure

-   Lower housing is cracked or distorted
-   Gear oil is contaminated with water or metal
-   Bevel gears or bearings are damaged
-   Propeller shaft is bent
-   Existing unit carries earlier reference 3817154

## 🛠️ Service Notes

-   The drive has to come off for this, so plan for the drive oil to be drained and for the seals, gaskets and bellows disturbed by the job to be renewed
-   Transfer or renew the internal parts exactly as the workshop manual for your drive directs, and set bearing preload and gear position using its measuring procedure rather than by feel — this is the part of the job that decides whether the drive lasts
-   Check every mating face and seal seat is clean and undamaged, and use only the lubricants and sealants specified for that drive
-   Pressure and vacuum test the assembled housing before the boat goes back in the water, then fill with the correct drive oil to the correct level
-   Confirm the kit matches your drive model and serial number before starting, as housings and their gear sets are not interchangeable between drive types

## 🔄 Supersession & Cross Reference

### OEM Supersession Chain

-   23370774 → Supersedes 3817154 → Supersedes 3583353 → Supersedes 3856832 → Supersedes 873089

### OEM / Related Numbers

-   3817154 earlier number superseded by this part
-   3583353 earlier number superseded by this part
-   3856832 earlier number superseded by this part
-   873089 earlier number superseded by this part

## 📦 Condition

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

## Details

- **Price:** 7897.09 AUD
- **Vendor:** Volvo Penta
- **Type:** Service & Repair Kits
- **Tags:** Volvo Penta

## Variants

| Variant | Price | Available |
|---------|-------|-----------|
| Default Title | 7897.09 AUD | In stock |

## Images

- 23370774 Gear Housing Kit | Genuine Volvo Penta Part

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> Source: [Sawley's Auto and Marine](https://www.sawleysautoandmarine.com.au/products/23370774-gear-housing-kit-genuine-volvo-penta)
> Updated: 2026-10-11