The valve cover gasket on the Cadillac Catera prevents oil from leaking into the engine compartment. There is a tight seal between the cylinder head and valve cover because of the gasket. Over time, high operating temperatures, as well as the oil, begin to break down the gasket and o-rings, both of which will need replacing.
Open the engine compartment and disconnect the negative battery cable using a wrench. Label each spark plug wire using the marker and masking tape to note the proper location. Remove the intake plenum and intake manifold from the engine using a wrench to remove the nuts. The intake plenum connects to the manifold.
Remove the spark plug wires off each plug by firmly grasping the boot and pulling. Remove the plastic routing retainer from the wires by pulling. Remove the valve cover bolts using a socket and ratchet. Pull the valve cover away from the cylinder head. Remove the old gasket and o-rings. Ensure you have all eight o-rings, as they may remain behind on the bearing caps.
Insert the new o-rings in the valve cover. Arrange the new gasket on the cylinder head and gently place the valve cover on top of it. Loosely install the valve cover bolts. Tighten the bolts with the socket and ratchet using an X-pattern until all are tight. Do not over-tighten the bolts. Replace the wires on each spark plug according to its label. Push it on until you feel each one snap into place.
Connect the intake manifold and tighten the nuts with a wrench. Connect the intake plenum to the intake manifold. Connect the negative battery cable and tighten the nut with a wrench.
