The head gasket is a device that prevents leaks of coolant or engine oil into the engine's cylinders. Located between the engine block and the cylinder head, it is normally discarded when it is removed. There are certain situations in which the gasket may be reused, as long as it is removed gently and is not bent or damaged in any way.
Inspect the gasket. If the gasket has any kinks or is bent in any way, it's probably not worth reinstalling. The gasket is sensitive and needs to fit perfectly in order to be reinstalled. If the bend is too great, it will harden the gasket and cause it to crack.
Clean the head gasket with carburetor or brake cleaner solvent and let dry before reinstalling. If it's too dirty, it may be too difficult to reinstall. Also, look for lacquer and other substances that may have stained or dirtied the gasket. Clean with a cotton rag and water.
Check to see if the engine was O-ringed. The O-ring is a thin copper wire that is wrapped around the gasket with super glue. If there is an O-ring present, it will not be possible to reinstall the head gasket.
Line up the gasket to the head studs to make sure it fits in place. It should be a tight fit. Unthread the studs and position the gasket on the deck. Thread in the studs and use a deburring tool around the head stud holes to relieve the tension. Use 100-grit sandpaper or sanding block to clean the remaining burr.
Spray the gasket with a thin coat of gasket dressing. The dressing will fill in the gaps between the head and the deck. Let it air-dry for about 15 minutes before applying a second dressing.
