Type 25 Water Expansion Tank - 1986-92 - Waterboxer Engines

This engine-mounted coolant expansion tank is a good quality reproduction of the later-style reservoir fitted to Volkswagen Type 25 / T3 buses from 1985 onwards. Designed for 1900cc and 2100cc petrol Waterboxer engines, it replaces the pressurised expansion tank located in the engine bay and includes the provision for a coolant level warning sender.

This tank forms a critical part of the pressurised side of the cooling system. As coolant heats and expands, the tank safely manages increased volume while maintaining correct system pressure. The integrated level sender hole allows the warning system to monitor coolant level and alert the driver if coolant drops below a safe level—helping to prevent overheating and serious engine damage.

Over time, original expansion tanks often become brittle, stained, or develop hairline cracks due to age and constant heat cycling. Replacing the tank is strongly recommended during cooling system refurbishment or if any signs of leakage or unreliable coolant warnings are present.

Manufactured to match the original later-style design, this replacement tank offers correct hose connections, mounting points, and capacity for a straightforward, factory-style installation.

How it works

Coolant expands as engine temperature rises, increasing system pressure. This pressurised expansion tank absorbs that expansion while the cap regulates pressure. The coolant level sender (sold separately) monitors fluid height inside the tank and triggers the dashboard warning light if the level becomes too low.

Features & specifications

• Later-style pressurised expansion tank

• Includes coolant level sender hole

• Supplied with filler cap

• Two hose outlets:

  • Upper: 15.5mm OD x 10.4mm ID

  • Lower: 24.9mm OD x 19mm ID

• Good quality reproduction for long-term reliability

Fitment & installation notes

• Fits VW Type 25 / T3 petrol models from 1985–1992

• Suitable for 1.9 and 2.1 Waterboxer engines only

• Coolant level sender sold separately, if required:

  • 251919372 – Push-on connector type

  • 251919372A – Clip-on connector type

• Always compare with your existing reservoir whenever possible to confirm correct style

Engine compatibility (Later Style)

• DG 1.9 (08/85–07/92)

• SP 1.9 (08/86–07/89)

• DJ 2.1 (08/85–07/92)

• MV 2.1 (08/85–07/92)

• SR 2.1 (08/86–07/92)

• SS 2.1 (02/89–07/92)