After the oil seal is damaged, whether certain parts need to be removed during replacement depends on the type and location of the oil seal. Here are some common oil seal replacement parts that may need to be removed:
Crankshaft oil seal: Replacing the crankshaft oil seal usually does not require removing the entire engine because the crankshaft oil seal is not on the same plane as the engine. However, it may be necessary to remove the crankshaft pulley to replace the crankshaft front oil seal. If the crankshaft rear oil seal is damaged, the engine may need to be lifted to replace it, because the crankshaft rear oil seal is located in the engine and transmission joint.
Camshaft oil seal: Replacing the camshaft oil seal requires disassembling the engine. Because the camshaft is located on the cylinder head, and the cylinder head is connected to the cylinder block. This process is more complex, requires professional technology and equipment, it is recommended that professional maintenance personnel operate.
Valve oil seal: If a problem with the valve oil seal is determined and the problem involves multiple cylinders, it may be necessary to remove the engine cylinder head to replace the valve oil seal. If only one or two cylinders are involved, it may not be necessary to remove the cylinder head, but it may be necessary to hold the valve or take other measures to replace the oil seal.
Please note that the above recommendations are for reference only, and which parts need to be removed when replacing the oil seal need to be determined according to the model, the oil seal location and the specific situation. If you are not sure how to do it, it is recommended to consult a professional repairman or an auto service shop.