EVIL ENERGY Coolant Overflow Tank Radiator Overflow Bottle Universal 800ml

Q: How does a coolant overflow tank work?

A: As the engine warms up, coolant expands and builds pressure in the radiator. When the pressure passes the rating of the radiator cap, the cap releases coolant through the coolant overflow hose into the coolant overflow tank instead of onto the ground. The EVIL ENERGY 800ml aluminum radiator overflow tank catches that coolant in a sealed bottle, while a 1/16 in vent hole on top lets air escape so the bottle never builds pressure. The tank works with cooling systems where the pressure cap sits on the radiator.

Q: Why does my coolant reservoir overflow after driving?

A: Some coolant movement after a drive is normal: coolant keeps expanding for a few minutes after shutdown as engine heat soaks into the system. A coolant reservoir that overflows after driving is usually overfilled, so the expanding coolant has no room and escapes through the vent. Fill the 800ml coolant overflow tank only to about one-third with the engine cold. If overflow continues at the correct level, test the radiator cap and watch the temperature gauge for signs of overheating.

Q: Why is my coolant reservoir boiling and overflowing?

A: Coolant that looks like it is boiling in the reservoir is often bubbling from air or combustion gases rather than true boiling. Common causes include trapped air after a coolant change, an engine that is overheating from a stuck thermostat or clogged radiator, a weak radiator cap, or a head gasket leak pushing exhaust gas into the cooling system. Stop driving, let the engine cool completely, and have the cooling system pressure-tested and checked for combustion gases before continuing to drive.

Q: Why is my coolant tank overflowing every time I drive, even at the right level?

A: When a coolant tank keeps overflowing at the correct cold level, the cooling system is pushing out more coolant than normal. Check the radiator cap first, since a worn seal can release coolant too early. Then look for a partially clogged radiator, a failing water pump, a thermostat that sticks closed, or an electric cooling fan that is not switching on. A larger coolant overflow tank will not fix the root cause, so diagnose the system before replacing parts.

Q: Which 800ml kit should I choose: Black Bottle, Orange Line or Silver Bottle?

A: All three kits use the same 800ml aluminum coolant overflow tank and hardware. Choose the Black Bottle with black NBR hose for a clean, stealth look on a daily driver. Choose the Orange Line with orange PVC hose for custom builds where a high-visibility coolant overflow hose is easy to spot. Choose the Silver Bottle with black NBR hose for classic cars, restomods and polished engine bays.

Q: Is an 800ml radiator coolant overflow tank big enough for my engine?

A: The 800ml radiator coolant overflow tank suits most 4-cylinder and 6-cylinder engines, compact engine swaps, tractors and UTVs with stock-size radiators. The slim 2.95 in diameter and 7.48 in height also fit tight engine bays where a larger tank will not. For V8 engines, LS swaps, oversized radiators or trucks that tow, choose the 1L or 2L aluminum coolant reservoir for a larger expansion margin.

Q: Can the 800ml tank replace the engine coolant reservoir on my car?

A: Only if the original part is a vented overflow bottle. Many modern cars, including many BMW, Volkswagen, Audi, Chevy Cruze and Ford Focus models, use a pressurized engine coolant reservoir that carries the pressure cap and is part of the sealed cooling system. A vented coolant overflow tank cannot replace a pressurized reservoir. If your radiator has its own pressure cap, the 800ml tank is a direct upgrade; if not, choose a vehicle-specific coolant reservoir tank.

Q: What size coolant overflow hose does the tank use?

A: The tank outlet measures 0.39 in (10 mm) OD and connects to the included 5/16 in ID coolant overflow hose. Run the hose from the overflow nipple on the radiator neck to the tank, and secure both ends with the included hose clamps. If the radiator nipple is a different size, use a hose barb adapter or a reducer so both connections seal tightly.

Q: Can I use the tank as a radiator water overflow tank for tractors, UTVs or track cars?

A: Yes. The 800ml tank works as a radiator water overflow tank or antifreeze tank on compact tractors, UTVs, side-by-sides and track cars, replacing cracked plastic bottles and catching coolant pushed out under hard use. Use the same coolant mix that is already in the cooling system. For track days, check the current rules of the track or sanctioning body, since some restrict antifreeze or set catch-can requirements.

Q: How full should the overflow tank coolant level be?

A: With the engine cold, keep the overflow tank coolant level at about one-third of the bottle, and use the same coolant that is already in the cooling system. The empty space above the coolant gives hot coolant room to expand. Check the level when the engine is cold, before long road trips and after any cooling-system service, and never let the bottle run completely empty.