GM 21998157 Mount Assembly, Engine

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Engine mounts seldom require attention, but broken or deteriorated mounts should be replaced immediately to prevent damage to driveline components. During the check, the engine must be raised slightly to remove the weight from the mounts. Begin by raising the vehicle and securely supporting it on jackstands, then position a jack under the engine oil pan with a large block of wood between the jack head and the oil pan, carefully raising the engine just enough to relieve the weight from the mounts, ensuring not to support the entire weight of the engine with the jack. Inspect the mounts for any cracks, hardened rubber, or separation from the metal plates, noting that the rubber may split down the center. Check for any relative movement between the mount plates and the engine or frame using a large screwdriver or prybar; if movement is detected, verify the tightness of the mount fasteners before concluding that the mounts are faulty, as broken mounts typically allow the engine to move easily when pried or under load. To replace the mounts, disconnect the cable from the negative terminal of the battery, remove the coolant reservoir and air filter housing, and attach an engine hoist to the top of the engine for lifting, avoiding the use of a jack under the oil pan to prevent damage to the oil pump pick-up. If a hoist is unavailable, casting jugs on each side of the engine block can support the engine's weight during the replacement process. Remove the engine mount through-bolts and the engine mount-to-frame bracket bolts, then raise the engine slightly to unbolt the mount from the block and remove it from the vehicle. Installation follows the reverse order of removal, using non-hardening thread-locking compound on the mount bolts and ensuring they are tightened securely.

Raise the vehicle and support it securely on jackstands.