2004 Toyota Sienna - Valve Cover Gaskets

Maintain Engine Health With Valve Covers

The valve covers keep oil inside your engine and provide access to your valves, camshaft(s), rocker arms, and more when needed. Valve covers are typically sealed with a gasket against the cylinder head to prevent oil leaks and maintain internal engine pressures. These gaskets may be made of cork on older vehicles, but most newer vehicles have rubber or silicone valve cover gaskets for a tight, long-lasting seal. Valve cover gaskets can fail over time due to normal wear and tear, excessive heat, or crankcase ventilation issues that cause extreme internal engine pressure and vapor buildup that can push on the gaskets from the inside. If your valve cover gasket has suffered damage or failed, and you may notice oil leaking from your valve covers, and due to their location, this oil could end up on other parts of the engine and make the issue difficult to diagnose. When oil leaks from the valve covers, it will often land on the exhaust manifold, which will burn the oil off rapidly at operating temperatures and cause a notable smell. Oil burning off on the exhaust manifolds not only causes unpleasant odors, but can also cause a fire, depending on the amount of oil escaping. Oil may also leak onto your spark plugs, which can prevent them from receiving the power they need to ignite the fuel mixture and cause misfires and a rough idle. If you've experienced these issues or noticed low oil levels or grease buildup on your engine, check around the valve covers for signs of leaks and replace the valve cover gaskets if they are no longer sealing properly. At O'Reilly Auto Parts, we carry valve cover gaskets and gasket sets, head gaskets, intake and exhaust manifold gaskets, and more for a complete repair.