Type 25 Water Hose Flange - Right Hand Cylinder Head - 1985-92 - Waterboxer

This plastic water pipe flange is a direct replacement coolant outlet fitted to the right-hand (driver’s side on RHD models) cylinder head on Volkswagen Type 25 (T25) Waterboxer engines from 1985 onwards. It forms a vital connection point between the cylinder head and the external coolant pipes and hoses, allowing hot coolant to exit the head and circulate through the cooling system.

Mounted directly to the cylinder head, this flange seals against the head with a gasket and provides a secure mounting point for the coolant pipework. Over time, original plastic flanges can become brittle due to repeated heat cycles, leading to cracks, warping, or coolant leaks. Replacing a tired or leaking flange is essential to maintaining correct cooling system pressure and preventing coolant loss or overheating.

Manufactured to original specifications, this replacement flange offers a precise fit and restores factory coolant routing. It is suitable for both 1.9 and 2.1 petrol Waterboxer engines and is ideal when renewing coolant hoses, replacing corroded pipes, or carrying out engine or cooling system maintenance.

How it works

Coolant flows out of the right cylinder head through this flange and into the cooling circuit, where it is directed to the radiator and thermostat system. A secure, leak-free seal at this point is critical, as any failure can result in pressure loss, air ingress, or rapid coolant loss.

Fitment & installation notes

• Fits right-hand cylinder head (RHD driver’s side)

• Suitable for 1.9 and 2.1 Waterboxer petrol engines

• Direct bolt-on replacement with factory-style hose connections

• Gasket sold separately – always replace the gasket when fitting to ensure a proper seal

Required fitting part:

• Cylinder head coolant flange gasket – Part number: N90168502

This flange is a small but crucial component in the Waterboxer cooling system and is highly recommended as a preventative replacement on engines over 30 years old.

Engine compatibility

• DG 1.9 (10/84–07/92)

• SP 1.9 (08/86–07/89)

• EY 1.9 (10/84–07/89)

• MV 2.1 (08/85–07/92)

• DJ 2.1 (10/84–07/92)

• SR 2.1 (08/86–07/92)

• SS 2.1 (08/89–07/92)