The valve cover gasket on the 2001 Nissan Xterra should be changed when it starts leaking oil onto the side of the engine. Leaking oil, especially if it reaches the exhaust manifold, could cause a fire if it is allowed to build up on the exhaust or engine. The valve cover gasket is a press-in-place, edge-molded elastomer seal that is made to last longer than cork gaskets. The valve cover gasket also comes with the spark plug tube seals.
Loosen the clamps on the Nissan Xterra's air ducts, using a screwdriver. Pull off the air ducts and remove the air cleaner box using the appropriate socket. Mark all the vacuum lines and wiring harness connectors that run over the valve cover, including the location of the spark plug wires. Remove the vacuum lines, wiring harness connectors and spark plug wires.
Remove the valve cover retaining bolts in numerical order. Remove the valve cover from the engine. If the valve cover doesn't come off easily, tap it with a rubber mallet.
Clean the valve cover gasket-mating surfaces on the valve cover and the engine using the rubber scraper and rags.
Smear a thin layer of RTV silicone on the valve cover. Press the valve cover gasket into the RTV. Remove the grommets from the spark plug tubes, if they did not come off with the valve cover. Install new grommets onto the spark plug tubes.
Place the valve cover onto the lifter valley. Tighten the bolts in order as depicted in the repair manual to 80 inch-pounds of torque. Reinstall the plug wires. Reattach the vacuum lines and wiring harness connectors. Reinstall the air cleaner box and air duct. Tighten the clamps on the air duct.
