Gaskets & Seals

WHAT IS THE DIFFERENCE BETWEEN A GASKET AND A SEAL?

The terms gasket and seal are used interchangeably. Both parts perform essentially the same function, but there are some importance differences to consider.

What is a gasket?

A gasket is a mechanical seal which fills the space between two or more flat mating surfaces or flanges, used as static seals. Gaskets are cut into different shapes to fit the components they are being installed on to prevent leaks between the parts that are under compression.

Here are some of the different types of gaskets used in vehicles:

• Head gasket: Located between the engine block and cylinder head, this gasket provides the seal for coolant and oil to circulate. A blown head gasket happens when this gasket fails.
• Valve cover gasket: Also referred to as the rocker cover gasket, this gasket sits at the top of the engine and prevents oil leaks by sealing the cylinder head and valve cover when bolted in place.
• Oil pan gasket: This gasket is located between the oil sump and the bottom of the engine block to prevent oil leaks. Sometimes gasket maker or an RTV sealant can be used as an oil pan gasket replacement.
• Manifold gasket: There is an exhaust manifold gasket and an intake manifold gasket, each used to seal the gap between the manifold and the engine to prevent air, coolant, and oil from leaking.

What is a seal?

Seals are almost the same thing as gaskets but are used between moving engine parts, pumps, and shafts that rotate. Seals tend to be flat and round and have an outer ring that is metal and an inner ring that is made of rubber. Seals are used in the engine, transmission, differential, air conditioning, power steering, fuel system, and more.

Here are some common seals that need replacement:

• Engine seals: These prevent fluids such as motor oil, ATF, and fuel from leaking. A leaking rear main seal is a common cause for replacement on used and high-mileage engines.
• Drivetrain seals: These include all seals related to the transmission, differential, and CV joints, such as input and output shaft seals.
• Door seals: Also known as weatherstripping, these are rubber seals that go around your doors, windows, and trunks to keep the weather out.

DIFFERENT TYPES OF GASKETS AND SEALS

When choosing a gasket or seal, it's important to know what material is best suited to your application.

Rubber: EPDM rubber gaskets and seals are more resistant to wear and tear and made to be resistant to oils and petroleum products that cause swelling in other gasket materials.

Metal: Typically used where an EPDM gasket or seal cannot support the parts that are under compression. Metallic and semi-metallic gaskets are used for higher-temperature and higher-pressure applications.

Paper: Used to make quick and economical gaskets and seals. Often made of cellulose fibre, gasket paper can resist oil, petrol, air, water, alcohol, grease, and most solvents.

Liquid: Liquid RTV silicone cures to form a silicone rubber gasket seal. Gasket maker is ideal when an OEM gasket or seal is unavailable or backordered.

REPLACE BLOWN GASKETS AND SEALS

At NAPA Auto Parts, we have a large selection of gaskets and seals. Visit your nearest NAPA store to find the best gaskets and seals and for your car, truck, or SUV.

Some gaskets are easier to replace than others. If you're considering replacing a gasket on your own, read our NAPA blog article on how to change a gasket. If you prefer to have your vehicle checked by a professional, head to a NAPA AUTOPRO centre near you and let us inspect and service your vehicle for you.