Type 25 Water Expansion Tank (Pressurised Tank) - 1983-85 (DG Engines) + 1984-92 Turbo Diesel (JX Engines)

This engine-mounted coolant expansion tank (also known as the coolant reservoir) is a high-quality replacement for VW Type 25 / T3 buses fitted with 1900cc–2100cc petrol engines and 1600cc–1700cc diesel engines from 1984 to 1992. It is the earlier-style round expansion tank (not the very early square version, OE part number 068121405D, which is no longer available).

Located in the engine bay, this tank forms the pressurised side of the cooling system and is critical to correct coolant circulation and pressure control. It features a dedicated hole for the coolant level warning sender, allowing the dashboard warning system to alert the driver to low coolant levels before serious engine damage can occur.

Manufactured to match the original factory shape and mounting points, this replacement tank offers a reliable solution for cracked, yellowed, or leaking original reservoirs. Age and heat cycles often cause original tanks to become brittle, making replacement essential for cooling system safety and reliability.

How it works

As coolant heats and expands, pressure builds within the cooling system. This pressurised expansion tank allows for controlled expansion while maintaining system pressure. The level sender fitted to this tank monitors coolant level and triggers the dashboard warning light if the level drops, providing early warning of leaks or coolant loss.

Maintaining a sound, leak-free expansion tank is especially important on Waterboxer engines, where correct cooling system pressure is vital for engine longevity.

Features & specifications

• Pressurised engine bay expansion tank

• Includes coolant level sender hole

• Supplied with filler cap

• Two outlet sizes: 34.8mm and 27.7mm

• Direct replacement for the common “early-style” tank

• Manufactured for long-term durability and resistance to heat and pressure

Fitment & installation notes

• Fits most T25 / T3 petrol and diesel models (1983–1992)

• Coolant level sender sold separately, if required:

  • 251919372 – Push-on connector type

  • 251919372A – Clip-on connector type

• Always compare with your existing tank whenever possible to confirm compatibility

Engine compatibility

Petrol – Waterboxer (from chassis F24-D-089113>>):

• DF 1.9 (03/83–07/92)

• DG 1.9 (03/83–07/85)

• DH 1.9 (03/83–07/85)

• EY 1.9 (10/84–07/89)

• GW 1.9 (03/83–07/85)

Diesel:

• KY 1.7 diesel (08/84–07/92)

• CS 1.6 diesel (12/83–07/85)

• JX 1.6 turbo diesel (12/83–07/92)