G3 Breather Hose - Rocker Cover To Engine Block - 1.9 Diesel

This engine breather hose connects the crankcase oil separator on the engine block to the rocker (cylinder head) cover breather, forming a critical part of the crankcase ventilation system on Volkswagen 1.9 Diesel, Turbo Diesel, SDI and TDI engines.

Its job is to route blow-by gases and oil vapour safely back into the intake system while maintaining the correct crankcase vacuum. As these hoses age, they commonly become hard, brittle, and split, which can lead to oil leaks across the engine, loss of vacuum, increased crankcase pressure, and rough or erratic running—especially noticeable on TDI engines.

This is a direct replacement pipe, correctly shaped to fit between the lower crankcase breather and the rocker cover outlet. Replacing a cracked breather hose helps restore proper engine breathing, reduces oil misting, and prevents unmetered air leaks that can affect drivability and emissions.

What this hose does

• Connects crankcase oil separator to rocker cover breather

• Maintains correct crankcase ventilation and vacuum

• Prevents oil leaks and oil vapour escape

• Helps avoid rough idle and erratic running on diesel engines

How it works

During normal operation, combustion gases that pass the piston rings are vented through the crankcase breather system. This hose allows those gases to flow safely from the engine block to the rocker cover and intake system, where they are re-burned. A sealed, intact hose is essential for correct pressure regulation.

Fitting notes & recommended associated parts

• Check breather connections for oil sludge or blockage

• Inspect the oil separator and clean if required

• Replace any brittle clips or seals at the same time

• Ensure hose is fully seated to avoid vacuum leaks

• Ideal to replace during rocker cover gasket or timing belt work

Engine Code Compatibility

• 1Y – 1.9 Diesel

• AAZ – 1.9 Turbo Diesel

• 1Z – 1.9 TDI

• AEY – 1.9 SDI

• AHU – 1.9 TDI

• AFN – 1.9 TDI

• ALE – 1.9 TDI

Full Vehicle Fitment Details

VW Golf Mk3

1991 – 1999 | 1.9 Diesel / TD / TDI / SDI

• Hatchback

• Estate (Variant)

• Hatchback Van / Estate Van

• Engine codes: 1Y, AAZ, 1Z, AEY, AHU, ALE, AFN

VW Golf Mk3 Cabriolet

1996 – 2002 | 1.9 Diesel

• Engine codes: 1Y, AEY

VW Polo Mk3 (6N) / Polo Classic (6V2)

1995 – 2002 | 1.9 Diesel

• Hatchback

• Saloon (Classic)

• Engine codes: 1Y, AEY, AAZ, AFN

VW Caddy

1995 – 2009 | 1.9 Diesel

• Caddy Mk2 (Pickup, MPV, Box Body)

• Caddy Mk3 (MPV)

• Engine codes: 1Y, AEY, AHB, AHU, ALE, 1Z

VW Vento

1991 – 1998 | 1.9 Diesel

• Saloon

• Engine codes: 1Y, AAZ, AFN

VW Passat

Passat B3 / B4 (1989–1997)

• Saloon

• Estate

• Engine codes: 1X, AAZ, 1Y

Passat B5 / 3B (1996–2000)

• Saloon

• Estate

• Engine codes: AHU, AFN

VW Sharan I

1995 – 2000 | 1.9 Diesel / TDI

• MPV

• Engine codes: AHU, AFN

Fitting Position

• Lower (engine block / oil separator)

• Cylinder head cover (rocker cover)