Type 25 Water Hose - Thermostat Housing To Metal Pipe Which Goes To The Oil Cooler

This replacement rubber coolant hose connects the thermostat housing to the oil cooler pipe on 1900cc and 2100cc petrol Waterboxer engines fitted to VW Type 25 / T3 buses. It is a key hose in the Waterboxer cooling circuit, ensuring proper coolant flow through the water-cooled oil cooler, which helps regulate both engine oil and overall engine temperature.

On Waterboxer engines, the oil cooler relies on a steady supply of coolant from the thermostat area. This hose allows coolant to flow from the thermostat directly into the oil cooler circuit. Any deterioration in this hose—such as cracking, swelling, or softening—can quickly lead to coolant leaks and reduced oil cooling efficiency. Replacing it with a correctly moulded hose is essential for reliable temperature control and long engine life.

Manufactured from high-quality NBR fabric-reinforced rubber, this hose is formed to the exact original shape and specification, ensuring:

• Perfect fit and correct routing

• Secure sealing at both ends

• Resistance to heat, pressure, and vibration

• Long service life in demanding engine bay conditions

What this hose does and how it works

Coolant exits the thermostat housing and flows through this hose into the oil cooler, where it absorbs heat from the engine oil. The coolant then continues through the cooling system. A sound hose here ensures stable oil temperatures, efficient cooling, and correct thermostat operation.

Fitment

• Vehicle: VW Type 25 / T3

• Years: 1984–1991

• Engines: 1900cc & 2100cc petrol Waterboxer

• Application: Thermostat to oil cooler pipe

Engine code compatibility

• DG: 1.9 (02/85 – 07/86)

• SP: 1.9 (08/86 – 07/88)

• DJ: 2.1 (01/86 – 07/92)

• MV: 2.1 (08/85 – 07/92)

• SR: 2.1 (08/86 – 07/92)

• SS: 2.1 (08/89 – 05/92)

Quality

• NBR fabric-reinforced rubber

• OE-correct moulded shape

• Designed for long service life

Fitting requirements (sold separately)

• 19mm hose clip: N0164011

• 23mm hose clip: N0164021

Fitting notes

• Always replace hose clips to ensure even clamping

• Check oil cooler stubs and thermostat outlet for corrosion

• Refill with the correct coolant and bleed the cooling system fully after installation

An essential cooling system hose that helps keep oil temperatures stable, coolant flowing correctly, and your Waterboxer engine protected.