Q: How Do the Gaskets in the Engine Protect It and Keep It Working?

asked by on December 01, 2015

How do the gaskets in the engine protect it and keep it working?

Oil/Fluid Leak Inspection $79.99 - $99.99 Get a Quote
Car is overheating Inspection $79.99 - $99.99 Get a Quote

Gaskets in an engine are used to seal one part to another due to variations from the machining or casting process. When a part is made, the surface will not be perfectly flat. There are small machining lines and surface imperfections that if two parts were put together, they would not be able to stop leakage of fluids. There may also be two different materials or thicknesses that will cause the two parts to expand and contract at different rates. The two parts would not be able to seal without the use of a seal or gasket.

There are many different gaskets used in an automotive engine. There are gaskets between the engine block and cylinder head. These gaskets may have layers of metal and different gasket materials to seal in the compression of the cylinder. The same gasket is used to seal oil and coolant passages from leaking. The gasket material will take up any imperfections between the two parts and any expansion or contraction of the parts as they get hot and cool back down. You may have a plastic part being sealed to a metal part or an aluminum part to a steel part.

The gasket material will be specific for the application. There are paper, plastic, metal, rubber or neoprene and silicone types. There are also gaskets made with combinations of these materials. The different materials are used to withstand the pressures of fluids or combustion. For example, you may see metal or paper gaskets on cylinder heads. Rubber or silicone gaskets are commonly used on valve covers and oil pans.

A gasket is only good as a one time use in most cases, except now some oil pan or valve cover gaskets are reusable and made from metal or plastic with different types of rubber or neoprene bonded to the metal or plastic. These type of gaskets use special shoulder bolts that cannot be overtightened in case they crush the gasket. Silicone can be used in place of a gasket and is called “Form-A-Gasket” by the manufacturer. The silicone is used in low pressure applications and works well when hardened to seal out coolant or oils. Water pump, oil pans, and thermostats use silicone on some applications.

Gaskets are designed to seal two parts in normal operations and will have a tolerance in temperature, pressures, or fluids that it can withstand. When these things go below or above and beyond the specified operating limits of the gasket, they can fail. When a gasket is new it may be able to withstand some operations out of these limits but an older gasket may not be able to. When a gasket fails there may be warping between the two parts and replacing the gasket may not be enough to seal the two parts again. For instance, if a head gasket starts leaking due to engine overheating](https://www.yourmechanic.com/services/car-is-overheating-inspection), the heat may warp the surface of the cylinder head to the point that a new gasket would not be able to seal again unless the head surface is machined flat again.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

What others are asking

My car won't start

Generally, the most common cause of a no start is the battery. Other causes are the fuel pump, starter, ignition switch, and the neutral safety switch. With the car turning off over speed bumps, that actually sounds completely related. That...

Lights on dash suddenly started flashing while driving, accompanied by car surging & stalling

The vehicle may have a problem with the power relay in the central junction box that powers the ignition and computer on the car. The relays and connections to the junction box will need to be checked if the problem...

Regarding valve cover gaskets

The valve cover gaskets will be the same for the GS or GSI. As long as the engine is a 1.6 liter engine you will not have any problem.

Coolant leak at front of engine

Coolant can leak from a variety of places. The only way to be certain is to see exactly where it's coming from. Large leaks are pretty easy to find. Small leaks may require special tools to locate. Some leaks are...

Leak from Manifold

You are correct. The most likely cause of an intake manifold leak, is gasket failure. These gaskets fail for a number of reasons and can be swapped out in a day. The majority of the process is removing the manifold...

Head gasket gone

If your head gasket has gone bad, stop driving the vehicle as soon as possible. A head gasket replacement does require removal of multiple engine parts to replace and is usually a costly repair. This is why many people decide...

Car starts, but dies

If you read your owners manual there is a special procedure to follow after a battery is disconnected or replaced. It's needed to relearn the idle and throttle procedure. If the procedure is not done, then it may take a...

Engine and lights pulsing

From the symptoms you describe, it would appear that the vehicle is experiencing an electrical problem. There is a technical service bulletin that addresses a problem similar to this, indicating that there may be a problem with the wires underneath...

When driving under 40 mph my car has started to sound like something is stuck in the engine.

Our mobile experts are well-equipped and ready to assist you with your vehicle's concerns. A noise while driving can be several things like a wheel bearing, a worn belt, or some other failing component of the vehicle. It is not...

Related articles

Symptoms of a Bad or Failing Cylinder Head Temperature Sensor
Common signs include long cranking time, engine performance issues, and the Check Engine Light coming on.
Symptoms of a Bad or Failing Thermostat
Common signs include the temperature gauge reading being very high or changing erratically, engine overheating, and coolant leaks.
How Does a Radiator Keep an Engine Cool?
Car radiators cool off your engine and prevent your engine from overheating. Coolant absorbs engine heat and dissipates it through the radiator.