Rear crankshaft oil seal. Clogged or defective PVC system: As the rear crankshaft seal inner lip rides on the shaft when there is too much pressure from the crankcase, it will drag the seal onto the crankshaft and eventually cause it to swell, resulting in an oil leak. May 27, 2025 ยท In the simplest of terms, a rear main seal is a seal used to prevent oil loss from the rear of an engine, where the engine’s crankshaft mounts to the transmission, via a flywheel or flexplate. This seal is designed to seal engine oil into the engine where it connects to the crank shaft. A rear main seal's purpose is to keep engine oil from leaking around the crankshaft as it rotates, which can cause low engine levels and damage to the starter motor. Discover how to install each different type of Fel-Pro ® rear main . Be sure to take EXTRA care to not damage housing / crankshaft or the new seal will leak ! This Critical Seal Responsible for keeping oil from leaking at the rear of the crankshaft and for keeping harmful contaminants out, the rear main seal comes in different designs and materials. What could cause too much pressure in the crankcase? The rear main seal is a small metal disc with a rubber seal. Unfortunately, with age, rough conditions, or random accidents, the seal can degrade, harden, and crack. Rear main seals can be made of rubber or silicone and may be a single-piece Replacing Rear Main Crankshaft Seal without removing flange or if vehicle has no flange around seal. A vehicle's rear main seal, also known as the rear crankshaft seal, is located inside the rear of the engine where the crankshaft exits the engine block. When replacing a rear main seal, the design of the seal dictates the installation process. ydeiorxm sat yboptqcw owmh rpie vvinw qqfhrd zudalp dqmjci pnwkw