The mating surfaces of the head or block must be perfectly clean, flat and smooth.

Seals are classified by O.D. wall material, lip type, and whether they have a spring or not.
Major oil seals are specified in ISO 6194-1 and JIS B 2402-1.
Table 2 shows the common types of oil seals, while Table 3 shows the features of each type of oil seal.
Table 4 lists the JTEKT oil seal type codes and corresponding ISO and JIS standards.
Right Valve Cover Gasket: Essential Component for Engine Integrity
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One of the key benefits of the 25x47x7 oil seal is its high level of resistance to wear and tear. This makes it an ideal choice for use in heavy-duty machinery and equipment that is subject to constant movement and pressure. The seal is able to withstand the rigors of daily use without degrading or failing, ensuring long-lasting performance and reliability.
Assembling the oil seals is only possible with the right assembly tools. Due to the high risk of damage during assembly, it is important that you have tools with which you can work carefully. A bearing fitting tool set is ideal.
In conclusion, choosing the right spark plugs for your MK7 GTI is crucial for optimal performance and engine efficiency. Upgrading to high-quality spark plugs can improve throttle response, fuel efficiency, and overall engine performance. Brands like NGK, Bosch, and Denso offer a variety of spark plugs that are specifically designed for performance cars like the MK7 GTI. When choosing spark plugs, consider factors like heat range and electrode material to ensure you're getting the best performance out of your MK7 GTI.