Radiator Water Flange – 3C0 122 291 (Hudson)

Description

The 3C0 122 291 Radiator Water Flange by Hudson is an OE-style upper radiator coupler. Specifically, it reconnects the upper coolant hose to the radiator inlet port, maintaining the sealed, pressurized junction at the top of the primary cooling circuit. Furthermore, this coupler ships complete with its retaining spring and sealing O-ring. As a result, the full upper hose junction replaces in a single step without sourcing additional hardware. Because the 3C0 122 291 spans a broad range of PQ35 and PQ46-platform vehicles — including the VW Golf V/VI, Jetta V/VI, Passat B6/B7, CC, Eos, Beetle, Tiguan Mk1/Mk2, and Audi A3 8P — it is one of the most widely applicable coolant couplers in the VAG parts catalog. Therefore, always confirm your exact engine code and model year by VIN before ordering.

Over time, the plastic body of the 3C0 122 291 Radiator Water Flange weakens from constant heat cycling, sustained system pressure, and vibration at the upper hose junction. In particular, the coupling port where the upper hose locks into the radiator inlet experiences the most intense thermal expansion and contraction cycles during every drive cycle. Consequently, hairline cracks can develop at the port walls and hose barbs. Additionally, the sealing O-ring can harden, flatten, and lose its compression, breaking the tight junction between the hose and the radiator. Even a small seepage at this location quickly leads to gradual coolant loss, recurring low-coolant warnings, and — if left unaddressed — progressive engine overheating. Therefore, replacing the failing 3C0 122 291 promptly restores a factory-correct, leak-free upper radiator connection.

Signs Your Upper Radiator Water Flange Needs Replacing

Catching a failing 3C0 122 291 early prevents escalating cooling system damage. Therefore, watch for these warning signs:

• Coolant seeping or leaving dried residue around the upper radiator hose coupling at the top of the radiator

• Recurring low coolant level warnings despite topping off the reservoir, with no other obvious leak source

• A sweet coolant odor from the engine bay after the engine reaches normal operating temperature

• Visible cracking, crazing, or discoloration on the plastic coupler body or at the retaining spring groove

• The upper radiator hose feeling loose at the coupling connection or failing to lock in with a firm click

If any of these symptoms appear, replace the 3C0 122 291 without delay. Additionally, pressure-test the cooling system after installation to confirm no other junction is seeping before returning the vehicle to service.

3C0 122 291 Radiator Water Flange — Key Features

• OEM Reference: 3C0 122 291 (Hudson OE-style aftermarket)

• Upper radiator hose coupler — connects upper coolant hose to radiator inlet

• Supplied complete with retaining spring and sealing O-ring

• Precision-molded plastic/composite body to match OE connector geometry and port dimensions

• Broad PQ35/PQ46 platform compatibility — VW Golf, Jetta, Passat, CC, Eos, Beetle, Tiguan; Audi A3

• Compatible with factory-style hose clamps (where applicable)

• Cost-effective OE-style alternative to the Genuine VW/Audi dealer component

• Direct-fit replacement — no modifications required

Service Notes for the 3C0 122 291 Radiator Water Flange

• First, confirm fitment by VIN and engine code — the 3C0 122 291 spans many models and engine variants; always match the exact part number and hose configuration before installation

• Next, install the supplied retaining spring and O-ring — never reuse the old hardware on a new coupler, as worn seals will not maintain the required compression

• Also, inspect the upper radiator hose for softness, swelling, or cracking at the coupling end; replacing it together with the flange is best practice on high-mileage vehicles

• Then, verify the upper hose locks fully into the new coupler with a firm click before pressurizing the system

• Finally, refill with VW/Audi-approved G12++/G13 coolant and bleed the cooling system completely to eliminate air pockets before returning the vehicle to service

3C0 122 291 Radiator Water Flange — Compatibility & Applications

Always verify fitment by VIN before ordering. Multiple variants may exist within the same model year.

Note: Fitment varies by engine code and production date within each model year. Always confirm by VIN before ordering.

Cross Reference Numbers

• 3C0 122 291 (VAG OEM reference — Hudson OE-style replacement)

• 3C0-122-291 (alternate formatting)

• 3C0122291C / 3C0122291D (superseding variant suffixes — verify which applies to your vehicle)

Additional information