Parts for your 2017 Holden Barina-Radiator cap

2017 Holden Barina radiator-cap: is there one, and does it matter?

Short answer: a traditional radiator cap isn’t used on the 2017 Holden Barina (TM series). This model runs a sealed, pressurised cooling system that uses a coolant surge/expansion tank with its own pressure cap. The radiator itself has no filler neck, so there’s no radiator-mounted cap to service or replace.

Why it’s set up this way: the Barina’s GM T300 cooling layout fills and de-aerates at the highest point in the system — the surge tank. The cap on that tank manages pressure and vacuum recovery, while also being the place you check and top up coolant. It improves packaging, helps reduce air pockets, and makes hot-opening warnings simpler, because owners are only interacting with one clearly labelled cap. It’s also a cleaner emissions approach, as the system stays closed and purges air more effectively.

What to maintain instead: focus on the coolant surge tank cap and the tank itself. Inspect the cap’s seal/O-ring for cracks, hardening, or coolant crust. If the cap no longer holds pressure (you might notice hoses going soft and collapsing after cool-down, slow overheating in traffic, coolant smell, or overflow around the tank), replace it with an OE-quality cap that matches the pressure rating printed on the original cap and specified for the TM Barina. Always work stone cold, use the correct Dex-Cool-compatible coolant mix, and fill to the tank’s marks — not the brim.

Technical sources referenced:

• Holden Barina TM Owner’s Handbook (2017): Cooling system instructions refer to the coolant surge/expansion tank cap, not a radiator cap.
• GM Global Service Information (Chevrolet Sonic/Barina T300): Cooling System Description and Operation specifies a pressurised surge tank as the fill/pressure point, with no radiator-mounted cap.
• ACDelco parts catalogue for TM Barina: lists Engine Coolant Reservoir (Surge Tank) Cap, no separate radiator cap listing for this model year.

Popular questions

Does the 2017 Barina have a radiator cap?
No — it uses a pressurised coolant surge tank with a cap. The radiator has no cap or filler neck. All filling and pressure control happen at the surge tank.

Where do you top up coolant on a 2017 Barina?
At the translucent surge/expansion tank on the passenger side of the bay (varies slightly by market). Only open when cold and fill to the “COLD” mark with the correct Dex-Cool-compatible coolant mix.

What cap should be replaced if there’s a pressure issue?
Replace the coolant surge tank cap with an OE-spec part that matches the pressure rating printed on your original cap. If the tank is discoloured, cracked, or weeping at the seam, replace the tank as well.