Coolant is added to the expansion tank (coolant reservoir) in the engine bay. Fill it only when the engine is cold and keep the level between the MIN and MAX marks; never open the cooling system cap while it is hot.
How the Tucson's cooling system works
The 2019 Hyundai Tucson uses a closed, pressurized cooling system that circulates ethylene glycol–based coolant through the engine, radiator and heater core. The translucent expansion tank serves as the reservoir for excess coolant as the system heats and expands, and it draws coolant back in as the engine cools. The cap on the reservoir maintains pressure in the system, so topping up is done through that reservoir rather than directly into the radiator on most models.
Where to add coolant
The filler point is the coolant expansion tank in the engine bay. It is a labeled, translucent plastic reservoir with MIN and MAX marks. The tank cap should only be removed when the engine is cold. Depending on the trim, the vehicle may rely primarily on the reservoir cap for access to the coolant, rather than a separate radiator cap.
Choosing the right coolant
Hyundai generally specifies a long-life ethylene glycol–based coolant (HOAT) that meets the vehicle’s specifications. Use the manufacturer's recommended coolant—either Hyundai Genuine Coolant or an equivalent HOAT coolant that is suitable for use in Hyundai engines—and mix 50/50 with distilled water unless you are using a pre-diluted ready-to-use formulation. Do not mix different coolant types and brands unless the manual explicitly allows it.
How to add and check coolant
Follow these steps to add coolant correctly and safely:
- Park on level ground and ensure the engine is completely cool before opening any caps.
- Open the hood and locate the coolant expansion tank (the translucent reservoir with MIN/MAX marks).
- Check the current level. If it is at or above the MAX line, do not add coolant unless you previously drained and refilled the system.
- If the level is below the MIN line, prepare a 50/50 mixture of coolant and distilled water (or use the ready-to-use pre-diluted coolant if specified).
- Slowly remove the reservoir cap (only when cold) and pour the prepared mixture into the tank until the level reaches the MAX mark. Do not overfill beyond MAX.
- Secure the cap tightly, start the engine, and run it with the heater on high to circulate the coolant. Check for leaks and allow the engine to reach operating temperature, then recheck the level after the engine cools.
- Discard any leftover coolant safely and clean up spills; never let coolant come into contact with pets or wildlife.
Note: If your Tucson uses a different fill point or has additional coolant ports, refer to the owner’s manual for exact instructions for your engine variant and trim.
If you notice persistent low coolant levels, overheating, visible leaks, or sweet-smelling exhaust, have the cooling system inspected by a qualified mechanic. A faulty radiator cap, a leaking hose, a blown hose, or a failing water pump can all cause coolant loss.
Safety and troubleshooting tips
Always follow safety precautions when handling coolant. Do not open any cooling system caps while the engine is hot, wear eye protection, and store coolant in a sealed container away from children and pets. If you are unsure about the right coolant type or how to refill, consult the owner's manual or contact a Hyundai service professional.
To summarize, in a 2019 Hyundai Tucson you add coolant to the expansion tank in the engine bay, using a 50/50 coolant/distilled water mix or a ready-to-use coolant as directed. Keep the level between MIN and MAX when cold, avoid opening the system hot, and defer to the owner's manual for your specific engine variant.
Summary
The coolant fill point for a 2019 Hyundai Tucson is the expansion reservoir in the engine bay. Use a Hyundai-approved HOAT coolant mixed 50/50 with distilled water (or a ready-to-use formulation), and never open the system while it is hot. Regularly check the reservoir level when the engine is cold and top up as needed to maintain proper cooling performance and prevent overheating.