Type 25 Metal Water Pipe - Oil Cooler To Thermostat - 1986-92 - 2100cc Waterboxer Engines

This replacement metal water pipe runs from the oil cooler to the thermostat housing on 2100cc petrol Waterboxer engines fitted to VW Type 25 / T3 buses. Designed specifically for 2.1 Waterboxer engines, it provides a rigid, reliable coolant link in a high-heat, high-load area of the cooling system.

On 2.1 Waterboxer engines, the oil cooler is water-cooled and relies on a controlled coolant flow to stabilise engine oil temperature. This metal pipe carries coolant from the oil cooler directly to the thermostat housing, where coolant flow is regulated based on engine temperature. Using a metal pipe in this location ensures consistent internal diameter, resistance to heat, and long-term durability compared to rubber hoses alone.

Over time, original pipes can corrode internally or externally, restricting coolant flow or causing leaks at the hose connections. Replacing a tired or corroded pipe restores correct coolant circulation and helps protect both oil temperature control and overall engine cooling performance.

What this part does and how it works

Coolant exits the oil cooler through this metal pipe and flows into the thermostat housing. When the engine is cold, the thermostat restricts flow to aid warm-up; as temperature rises, it opens to allow full circulation. A straight, corrosion-free pipe here is essential for smooth coolant flow and accurate thermostat operation.

Fitment

• Vehicle: VW Type 25 / T3

• Years: 1986–1992

• Engine: 2100cc petrol Waterboxer

• Application: Oil cooler to thermostat (metal pipe)

Engine code compatibility

• DJ: 2.1

• MV: 2.1

• SR: 2.1

• SS: 2.1

Fitting requirements (sold separately)

• 2 × 19mm hose clips: N0164011

Fitting notes / related parts

• Inspect the rubber hoses at each end and replace if hardened or cracked

• Check the oil cooler and thermostat housings for corrosion at the hose stubs

• Ensure the pipe is correctly aligned before tightening the hose clips

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

A durable OE-style replacement that plays a key role in oil temperature regulation, thermostat control, and reliable cooling performance on 2.1 Waterboxer Type 25 / T3 buses.