2012 Toyota Venza - Valve - Exhaust

Symptoms of a Leaking Exhaust Valve

The exhaust valve is located in the cylinder head and is designed to open and close at specific intervals during the engine's four-stroke combustion cycle. This combustion cycle controls the release of exhaust gasses from the combustion chamber after the fuel-air mixture has been ignited and the power stroke has taken place. To ensure effective sealing, exhaust valves and cylinder heads are machined with precise tolerances which prevent the escape of exhaust gasses when the valve is closed. The valve guides provide stability and guide the movement of the exhaust valve within the cylinder head, and valve seals are also installed to prevent oil above the valve from entering the engine. Engine valve failure is rare, but a timing failure in the engine can cause the piston to make contact with the valve, which can result in a bent valve that is unable to seal the cylinder. It is also possible to have a burnt valve from the engine overheating or using the wrong fuel, or valves may suffer from buildup that can prevent them from sealing fully. This can cause leaks around the exhaust valve during the compression stroke, leading to a loss of compression and misfiring. If you have a bad exhaust valve, you may notice rough engine operation and idle, decreased engine performance, misfires, a ticking noise coming from the engine, or bluish-white smoke coming from the exhaust. Replacing an engine valve is a substantial repair that will require an engine tear down, and it may be a good idea to have the cylinder head inspected at a machine shop to ensure a lasting repair. O'Reilly Auto Parts offers all the parts and tools needed to get the job done right, including intake and exhaust valves, gaskets, and a selection of engine rental tools for a complete repair.