- Milky or chocolatey-looking oil.
- Bubbles in the coolant.
- Low engine coolant.
- Overheating engine.
- Rough idling.
- Loss of power.
- White or gray smoke from exhaust.
Test for head gasket leak:
- Perform a compression test.
- Check for hydrocarbons in the coolant.
- Inspect the head gasket for signs of damage.