Water Pump Pulley (2 Piece) - Waterboxer Engines

This complete two-piece water pump pulley is a direct replacement for the original split pulley fitted to 1900cc and 2100cc water-cooled petrol Waterboxer engines used in Type 25 / T3 buses. Supplied as one front half and one rear half, it replaces the original OE pulley halves 025121031A and 025121031B.

The two-piece (split) design is intentional and essential on Waterboxer engines. It allows the pulley to be installed and removed without disturbing the water pump or surrounding components, making servicing far easier—especially in the confined engine bay of the T25/T3. When bolted together, the two halves clamp securely around the pump hub to drive the coolant pump via the auxiliary belt.

What this part does and how it works

The water pump pulley transfers rotational drive from the engine belt to the water pump. As the pulley turns, it spins the pump’s impeller, circulating coolant through the engine, radiator, and heater circuits. A true and properly aligned pulley is critical for:

• Correct belt tracking and tension

• Efficient coolant circulation

• Reduced bearing and belt wear

• Quiet, vibration-free operation

Worn, bent, or corroded pulley halves can cause belt squeal, uneven belt wear, or poor coolant flow. Replacing both halves as a matched set restores proper alignment and reliable cooling system performance.

Features

• Two-piece design (front and rear halves supplied)

• Direct replacement for original split pulley setup

• Enables easy installation and removal without removing the water pump

• Durable construction for long service life

Quantity

• 1 × Front pulley half

• 1 × Rear pulley half

Fitment

• VW Type 25 / T3: 1982–1992

• Engines: 1.9 & 2.1 petrol Waterboxer

Engine code compatibility

• 1900cc: DF, DG, GW, EY, SP

• 2100cc: MV, DJ, SP, SR, SS

Chassis / production notes

• DF, DG, GW 1.9 WBX from chassis 24-D-051-581 → 31/12/1982

• DF, EY 1.9 WBX from chassis 24-D-074463 → 28/02/1983

• SP 1.9 WBX: all years

• MV, DJ, SP, SR, SS 2.1 WBX: all years

Fitting notes / related parts

• Inspect the drive belt and replace if worn or glazed

• Check water pump bearing for play while the belt is removed

• Torque pulley fasteners evenly to ensure correct alignment

• Always set belt tension to factory specification after installation

Ideal for servicing, restoration, or replacing damaged originals, this complete split water pump pulley set keeps your Waterboxer cooling system running smoothly and reliably.