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

asked by on

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

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.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. How Do the Gaskets in the Engine Protect It and Keep It Working?

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

Get a quote

What others are asking

Q: i bought a used grade a motor and was wondeing if i needed to replace the gaskets on it. 2001 Mitsubishi eclipse

I would recommend looking for any seals or gaskets that may be leaking before installation of the used motor since it would be easier to change the parts with engine out. If no leak is detected then they do not...

Q: Check engine light keeps coming on

Unfortunately, the repair information I have for this vehicle and code are rather sparse. Doing a little research, I found this code stands for "Charge Air Cooler Efficiency Below Threshold." The most common cause of this code does appear...

Q: Engine misfiring in the sixth cylinder on a 2009 Ford Edge

Misfires can be caused by many things, but at least you know it is in the cylinder number six. What I would try next is to swap the ignition coil from six to one, and one to six. If the...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...