- One of the key functions of a mechanical oil seal is to prevent the leakage of oil or grease from the rotating shaft of a machine. This is achieved through the use of a flexible sealing lip that makes contact with the shaft and effectively seals the gap between the shaft and the housing. The seal is typically made from a durable elastomeric material such as rubber or polyurethane, which is resistant to abrasion and can withstand high temperatures and pressures.
In engine applications, square rubber gaskets are used to seal various components such as valve covers, oil pans, and intake manifolds. These gaskets help prevent oil and fuel leaks, ensuring the engine operates smoothly and efficiently.
square rubber gasket
The temperature range of the mechanism in which the seal is installed must not exceed the temperature range of the seal elastomer.




Note how the mounting nuts or bolts are fitted, then undo them. Have ready some wooden wedges to use as supports, and a strong helper to hold the engine steady.
Oil seal type or shape
No single physical property of rubbers is responsible for the successful performance of an oil seal or ‘O’ ring. The ultimate tensile strength, breaking elongation, modulus, shore hardness, creep and stress relaxation in tension and compression loads are all important physical properties that characterize a seal or ‘O’ ring. Compression strength and set together with stress relaxation or decay are important for effective sealing. The difference in these properties in a swollen seal is highly critical. An optimum swelling value in a fluid medium is a desirable feature. De-swelling decreases the seal pressure against the wall of the housing where the seal is fixed, leading to leakage. Over swelling minimizes the physical properties of the rubber. Seals made of polysulfide rubbers have extreme fuel resistance but undesirably high compression set. The effect of temperature on the seal is an important factor. Swelling under stress can increase at higher temperatures and a suitable compounding technique should be adopted to reduce this effect.
Elring
Viton Oil Seals
Aspects to consider when selecting oil seals
How are they used?