GDUKOP Engine Coolant Overflow Reservoir Tank with Cap — Direct-Fit 603-955 for Buick Encore & Chevy Trax, Heat-Resistant Plastic

The GDUKOP 603-955 engine coolant overflow reservoir tank with cap is a direct-fit replacement coolant expansion bottle designed to restore proper coolant level control for compatible Buick Encore and Chevy Trax models.

When an original coolant overflow tank becomes cracked, discolored, or begins to leak, the cooling system can lose the ability to maintain stable coolant levels and pressure. The GDUKOP 603-955 reservoir is manufactured from heat-resistant plastic and built to match OE dimensions and mounting points so you can replace the worn part without trimming, drilling, or adapting hoses. It ships with a matching cap and meets the reference OE numbers used by many service manuals.

Will this reservoir fit my vehicle?

This tank is engineered to directly replace the factory unit on specific Buick and Chevrolet small SUVs. Check your model year and engine size against the listed fitment to confirm compatibility before ordering.

• Compatible with Buick Encore: 2013–2021, L4 1.4L engines
• Compatible with Chevrolet Trax: 2013–2021 L4 1.4L and 2013–2019 L4 1.8L engines
• Matches OE reference numbers: 603-955, 13502353, 95201979, 95269001

How does this replacement improve cooling system reliability?

Replacing a damaged overflow reservoir prevents slow coolant loss and reduces the chance of air entering the cooling circuit. The GDUKOP tank holds expansion coolant and allows the system to recover fluid as temperatures change, helping the engine run with a stable coolant level.

• Durable, heat-resistant plastic resists cracking under engine bay temperatures
• Prevents leaks that can lead to low coolant warnings or overheating events
• Restores proper coolant recovery and pressure balance across the system

Is installation difficult and what comes in the box?

The reservoir replaces the original unit using the same mounting points and hose connections, so most installations require only basic hand tools and minimal mechanical experience. GDUKOP supplies the tank with a cap and designed hose outlets to match factory routing.

• Direct replacement—no trimming or modification needed
• Includes matching threaded cap for a secure seal
• Simple install: disconnect battery, drain small amount of coolant, swap tank, reconnect hoses

What materials and standards were used to make this tank?

The GDUKOP overflow tank is molded from engineered plastics chosen for thermal stability and chemical resistance to common engine coolants. That construction reduces the likelihood of premature failure from heat cycling or coolant exposure.

• Heat-resistant plastic construction suitable for under-hood conditions
• Resists cracks, warping, and coolant-induced degradation
• Manufactured to match factory dimensions and connector placements

Who is this for: The GDUKOP 603-955 coolant overflow reservoir is ideal for owners, mechanics, and fleet managers who need a reliable, cost-effective replacement for the original expansion tank on Buick Encore and Chevrolet Trax vehicles within the specified years and engine sizes. It's a practical choice if you see coolant loss, visible tank damage, or dashboard coolant warnings and want a straightforward, direct-fit swap to restore proper cooling operation.