Here are the most likely culprits:
* Head Gasket Failure: This is a serious problem. A blown head gasket allows coolant to mix with engine oil (resulting in milky oil) or to leak externally, often around the cylinder head. This needs professional repair.
* Cracked Cylinder Head or Engine Block: A crack in the engine block or cylinder head allows coolant to escape. This is also a major repair, potentially requiring engine replacement.
* Leaking Hose or Hose Clamp: A simple but important cause. Check all hoses connecting to the radiator, engine, and water pump for cracks, holes, or loose clamps. These are relatively inexpensive and easy fixes if this is the problem.
* Leaking Radiator: While less common than hose leaks, a crack or hole in the radiator itself can cause coolant to escape. Radiator repair or replacement may be needed.
* Water Pump Leak: The water pump circulates coolant. A leak in the pump's seal will result in coolant loss.
* Loose or Damaged Radiator Cap: A faulty radiator cap might not hold pressure properly, leading to coolant overflow. While this *might* be contributing to the problem, it's usually accompanied by other symptoms (like overheating) and is unlikely to be the sole cause of coolant pouring out.
What to do immediately:
1. Stop driving the vehicle immediately. Continuing to drive with a major coolant leak risks serious engine damage.
2. Do NOT add more coolant. This will only make the mess worse. Find and fix the leak first.
3. Have the vehicle inspected by a qualified mechanic as soon as possible. They will diagnose the specific cause of the leak and recommend the necessary repairs.
Ignoring this problem can lead to overheating, engine damage, and costly repairs. Get it checked out right away.
