AUTO·REPARE FR
Structure

Head gasket

Seals combustion, coolant and oil. It is not a scheduled service item.

Teaching inline-four schematic. Not a specific car. Head gasket

What it does

Often multilayer steel on recent engines. It fails after overheating or another fault — confirm with tests.

Between the block and the head.

Not a diagnosis. Interval and part number: the manufacturer’s schedule.

Common signs

  • Gas in the tank, foam.
  • Oily black coolant (other causes exist).
  • Overheating.

Already on the site

Black coolant (FR article)

Mayonnaise is not unique proof. Cost ranges in the coolant article are not a quote.