Place the ruler or straight-edge on edge diagonally across the head and block and look for gaps showing light anywhere between the ruler and block.

Oil gasket seals are used in various parts of the engine, including the valve cover, cylinder head, and oil filter housing. These seals are designed to prevent oil leaks and maintain the integrity of the engine components. The oil gasket seal ensures that the engine remains properly lubricated and free from oil leaks, contributing to its overall efficiency and reliability.

Figure 4.4. Scanning electron microscope (SEM) image of the surface quenched for (A) uncured rubber and (B) transmission electron microscope (TEM) image for cured rubber [64].

Leather oil seals are commonly used for parts that are exposed to dirt and poor lubrication. The major advantage of this material is that it can function in cases where synthetic rubber cannot function. They are used for shafts that have rough surfaces that are more than what rubber seals can handle. This is because they are pre-lubricated and have the capacity to absorb liquids.

Modern engine oils, such as the current SG classification for gasoline engines, contain a large fraction of additives, many of which are detrimental to fluoroelastomers. The primary functions of oil-additive packages are to protect metal parts, avoid deposits in the engine, minimize oil degradation, and adjust fluid viscosity. Little attention has been paid to avoiding damage to rubber seals. Instead, elastomer producers have been expected to provide new, higher-performing products at no increased cost to auto manufacturers. Among the additives with moieties that may attack fluoroelastomers at high temperature are detergents (phenolates), dispersants (succinimides, alkylphenol amines), and antioxidants (amines, sulfides, hindered phenols).⁴ Many of these components are multifunctional, containing phenol or amine groups that can dehydrofluorinate and crosslink VDF-containing fluoroelastomers, leading to loss of elongation and eventual embrittlement. However, the rate and extent of reactions with seals are affected by many factors, including whether air is present in the system. When oil is exposed to air at high temperature, additives may undergo considerable changes. For example, a significant fraction of amines may be oxidized to amides, which have little effect on fluoroelastomers.⁵