Here's why:
* Cylinder Head Gasket Failure: The cylinder head gasket seals the coolant passages within the engine block and cylinder head. If this gasket is blown or damaged, coolant can leak out from any number of points, including around head bolts. This is the most likely cause. The pressure in the cooling system pushes coolant through any weaknesses in the gasket.
* Cracked Cylinder Head: While less common than a blown gasket, a crack in the cylinder head can also cause coolant leakage. If the crack is near a bolt hole, coolant will leak out around that bolt. This is often accompanied by other symptoms like overheating, loss of compression, or white smoke from the exhaust.
* Loose or Damaged Bolt: Although less probable than the above, it's *possible* the bolt itself is loose, stripped, or improperly seated, allowing coolant to seep past. However, this is usually accompanied by visible signs of looseness or damage to the bolt or surrounding area.
Important Considerations:
* Severity of the Leak: A small weep might be manageable temporarily (but still needs attention!), while a significant leak necessitates immediate action to prevent engine damage.
* Other Symptoms: Look for other symptoms like overheating, white smoke from the exhaust, loss of engine power, or milky oil (indicating coolant mixing with the oil). These would strongly suggest a head gasket failure.
What to Do:
You should have a qualified mechanic inspect your engine as soon as possible. Ignoring a coolant leak can lead to catastrophic engine damage. A simple visual inspection might not be enough; pressure testing the cooling system is usually necessary to pinpoint the leak's source accurately. Repairing a blown head gasket or a cracked cylinder head is a significant job.
