Q: Do engine mounts seldom require attention, and should broken or deteriorated mounts be replaced immediately to prevent damage to driveline components in 5.7L,6.0L,6.2L V8 engine on Cadillac CTS?
A: 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. Raise the vehicle and support it securely on jackstands, then position the 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 without using the jack to support the entire weight of the engine. Inspect the mounts for cracked, hardened rubber or separation from the metal plates, noting that rubber may split down the center. Applying rubber preservative or WD-40 can help slow deterioration. Check for relative movement between the mount plates and the engine or frame using a large screwdriver or prybar; if movement is noted, check the tightness of the mount fasteners before condemning the mounts, as broken mounts typically allow the engine to move easily when pried or under load. Disconnect the cable from the negative battery terminal before proceeding with the removal of the air filter housing and air intake resonator. For the driver's side mount, remove the engine mount heat shield; for the passenger's side mount, disconnect the oil level sensor electrical connector, remove the starter, and disconnect the negative battery cable from the engine block. 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. Remove the engine mount bracket-to-engine block bolts from below, then the engine mount bracket-to-subframe bolts from above, followed by the engine mount bracket-to-subframe nuts and unscrewing the studs from the bracket. Raise the engine slightly until the engine mount can be removed, and installation is the reverse of removal, using non-hardening thread-locking compound on the mount bolts and tightening them to the specified torque. For 6.2L engines, have the air conditioning refrigerant discharged at a dealer service department or air conditioning shop, remove the shock tower crossbrace, and the air conditioning lines to access the mount top nut. Working below the vehicle, remove the engine mount-to-front suspension subframe nut and the engine mount-to-engine bracket nut. Attach an engine holding fixture or engine hoist to the top of the engine for lifting, and raise the engine slightly until the engine mount can be moved by hand. Unbolt the engine bracket from the engine block, remove it along with the engine mount, and separate the mount from the engine bracket. Installation is the reverse of removal, ensuring all bolts and nuts are tightened to the specified torque, and have the air conditioning system evacuated, recharged, and leak tested by the shop that discharged it.