How to Replace the Head Gasket on a 4.0 Ford

The Ford 4.0L engine, a reliable and relatively maintenance-free motor, has been used most frequently in the Ford Explorer and Ford Ranger. Despite the engine's reputation for solid performance, the head gasket occasionally becomes worn and needs replacing. The gasket seals the gap between the cylinder head and engine block to aid compression and prevent oil leaks. Though removing the head gasket is a lengthy process, you can still do it yourself, which will save the money you would otherwise spend on a mechanic.

Things You'll Need

  • Ratchet and socket
  • Drain pan
  • Spark plug wrench
  • Rubber mallet
  • Formula 409
  • Gasket sealer
  • Replacement gasket
  • Disconnect the negative battery cable using a ratchet and socket, then relieve pressure from the fuel system by following your vehicle owner's manual specifications. Different models feature different specifications for this process.

  • Place a drain pan beneath the radiator drain plug, remove the drain plug using a ratchet and socket, then drain the radiator into the drain pan.

  • Pull radiator hoses and electrical connectors from the cylinder head, then unbolt the radiator fan using a ratchet and socket, and pull the fan belt and shrouding out.

  • Pull the spark plug wires free from the plugs, then remove the spark plugs with a spark plug wrench.

  • Unbolt the drive shaft pulley and cylinder head using a ratchet and socket, then tap the cylinder head lightly with a rubber mallet until it comes free.

  • Remove the head gasket, clean the surface with Formula 409, coat both sides of the new gasket with gasket sealer, then install the new gasket and follow the previous steps in reverse to complete the installation.