Parts for your 2018 Volkswagen Amarok-Radiator cap

2018 Volkswagen Amarok radiator-cap: what’s fitted and what to service

Based on Volkswagen technical material for the Amarok (owner’s manual, factory repair manual/ELSA, and the VW parts catalogue), the 2018 Amarok does not use a traditional radiator cap on the radiator itself. Instead, the cooling system is a sealed, pressurised design that’s filled and vented through a coolant expansion tank with a pressure-relief screw cap. The radiator has no service cap. That cap on the expansion tank is the only place a driver or technician should open to check or top up coolant.

Why no old-school radiator cap on the 2018 Amarok?

• Higher fill point and better de‑aeration: the expansion tank sits high in the engine bay, helping purge air and maintain a consistent coolant level.
• Safety and service simplicity: one clearly marked cap means fewer hot surfaces to deal with and less risk of opening the wrong point when the engine’s warm.
• Packaging and durability: a sealed radiator improves packaging up front and reduces potential leak points in heavy‑duty ute use.
• Stable pressure control: the expansion tank cap manages system pressure and overflow/return, keeping boiling point up and coolant flow consistent.

For owners and techs, that means any “radiator-cap” talk on this Amarok really refers to the coolant expansion tank cap. It’s the blue or black screw cap on the translucent reservoir in the engine bay. Only open it when the engine is cold. If coolant needs topping up, use VW-approved coolant (G13 or G12evo spec) premixed 50/50 with demineralised water unless a ready-mix is used. Don’t mix unknown coolants.

Because the cap is a pressure valve, it can wear. If there are hard hoses when cold, hoses that collapse after shutdown, sweet smells, visible staining around the cap, coolant pushed out, or frequent low-level warnings, have the cap pressure‑tested and replace it if it won’t hold the printed rating. Inspect the cap’s seal for nicks or flattening and replace the cap if damaged. Hand-tighten only, no tools needed. Using a genuine or OE‑quality cap ensures the correct relief pressure.

Regular checks during servicing—coolant level and condition, cap seal condition, and a quick pressure test if overheating is suspected—will keep the Amarok’s cooling system happy, whether it’s the 2.0 BiTDI or the 3.0 V6 TDI.

FAQs

Does a 2018 Amarok have a radiator cap?
No. It uses a sealed radiator and a pressurised coolant expansion tank with a screw cap. That reservoir cap is where coolant is checked and topped up, and it performs the pressure‑relief job a traditional radiator cap used to do.

Where do you add coolant and what type should be used?
Top up via the expansion tank only, when the engine is cold. Use VW‑approved coolant (G13 or G12evo) as specified in the owner’s manual, ideally a 50/50 premix with demineralised water unless a ready‑mix is supplied. Avoid mixing different coolant types.

When should the expansion tank cap be replaced?
Replace it if the seal is perished or cracked, if there’s staining or coolant escaping around the cap, or if a pressure test shows it’s not holding the rated pressure. It’s cheap insurance against overheating and coolant loss.