Valve Train Components



The valve train typically includes the camshaft, valves, valve springs, retainers, rocker arms and shafts. On engines with traditional mounting of the camshaft in the cylinder block, the valve train also includes lifters and pushrods. Overhead cam engines may use more than one camshaft per cylinder head. Engines use different valve configurations, such as two, three, four or five valves per cylinder. These various valve arrangements are used for different engine breathing requirements. Some engines also use variable valve timing, which allows the engine to change breathing characteristics under different operating conditions.


The cylinder head's valves, when synchronized with the crankshaft of the cylinder block, allow the engine to "breathe". In an engine, this means pulling the air and fuel mixture into the cylinder, then pushing the burned exhaust gases out. The better an engine breathes, the more efficient it becomes.

Maintenance Tips/Suggestions

Check your owner's manual to see if your car requires periodic valve adjustments. Most cars no longer require them, but there are exceptions. To best care for the parts of the valve train, stick to a regular maintenance routine of oil and filter changes and proper cooling system care. Also check the owner's manual to find out what the maintenance interval is for the timing belt (if equipped). If the timing belt breaks on some engines, it can cause major damage to the valve train and other parts of the engine.

Use the right gasoline for your car as recommended in the owner's manual. In some cases, the use of premium fuel when it's not needed can cause deposits on the intake valves, which can cause performance problems. Some symptoms of problems in the valve train include an engine that makes a ticking noise, runs rough, bucks, surges, stalls, gets poor fuel economy or fails an emissions test. Since the same symptoms can also be caused by other engine systems, take your car to a qualified service professional to pinpoint the cause.

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