How To Replace The Gasket On The Car

- Aug 14, 2020-

The gasket is designed to seal any two surfaces to protect them from the liquid and gas in the engine. The gasket can be used to seal cast iron to cast iron or aluminum to cast iron. The gasket composition is directly related to the desired design and characteristics of the joint surface to be sealed. The gasket can be composed of paper, rubber, cork, steel and graphite. During normal engine operation, the gasket should be able to resist deterioration caused by liquids and high temperatures. The most popular gaskets are steel gaskets.


Tempered composite gasket

The steel lamination is a more prominent way to seal the cylinder head and cylinder block. Steel laminated gaskets can better control the combustion, once compressed, the thickness remains the same. Due to the superior sealing, the combustion space and piston position will ensure better control of combustion and engine emissions. Cylinder head gaskets also provide additional stress support during normal engine operation and fluctuating thermal operating conditions. Tension bolts help to seal the cylinder head and effectively block it and make them integrated. This prevents bending and possible cracking of related components, which will be subject to the internal stress of the engine.


When installing the gasket on the cylinder head and cylinder block, always ensure that the surface finish meets the surface finish specified by the original manufacturer. Do not apply any form of sealant or silicone on the cylinder head gasket surface as they are usually coated with silicone/Teflon type paint. This paint helps seal the cylinder head and cylinder block. Torque and re-torque the cylinder head bolts as needed according to the correct sequence and specifications specified by the original manufacturer.

When the engine or cylinder head is reworked in a bimetallic engine (cast iron block and aluminum cylinder head), the cylinder head bolts should always be replaced. Since the thermal expansion rate of aluminum is much greater than that of cast iron, cylinder head bolts are critical to maintaining the correct clamping pressure on the cylinder head gasket.

Cylinder head gasket installation guide:

Always ensure that the cylinder head and cylinder block surface are thoroughly cleaned and degreasing treatment

Use straight edges to check the straightness of the cylinder head and stopper. The longitudinal and transverse gap between the straight edge and the surface should not exceed 0.051mm

Make sure that the bolts, threads, washers and nuts are cleaned and not damaged.

Twist the cylinder head in the correct order and specifications specified by the original manufacturer.

Oil seal

The oil seal prevents external oil leakage while still maintaining adequate lubrication of the bearing or bushing assembly. Modern oil seals are made of molded synthetic rubber. This allows the seal to operate at high temperatures and increase shaft speed. Before installing the oil seal, check that the shaft and housing are thoroughly cleaned and free of debris. Check whether the sealing lip is not damaged and whether the clamping spring is in place. Use appropriate tools to install the oil seal, and install the oil seal concentrically into the housing. Where possible, slow rotational pressure movement will also help install the oil seal. The chucking spring in the oil seal generates a higher sealing load on the shaft, thereby improving the shaft speed and the sealing performance of the low-viscosity lubricant.


When choosing a suitable oil seal, always consider the following factors:

The diameter of the housing hole

Shell drilling depth

Shaft diameter

Shaft speed

Whether the application is one-way or two-way

Maximum temperature of sealing point

Fluid to be sealed

Any special operating conditions

Useful tip: Use a suitable thread tap to clean the cylinder head bolt holes to ensure that the bolt holes are clean and free of any debris. Unless the original manufacturer's manual specifies the application of oil, the cylinder head bolt threads should be free of any oil. Always apply a small amount of oil to the bolt head below the radius.