Car encyclopedia

Valve Adjustment

An engine valve is what allows air into (or exhaust out of) a specific cylinder. Each cylinder has at least one intake and one exhaust valve.

Why Should It Be Serviced?

Not performing a valve adjustment may result in excessive engine noise and could eventually affect engine performance, so it's important to have it serviced. If you don't, you may experience one or more of these symptoms:

  • Noise from engine
  • Engine misfire due to damaged valve

When Should It Be Serviced?

  • On engines requiring valve adjustment maintenance, this service is commonly performed every 15,000 to 30,000 miles or when an abnormal valve train noise is noted
  • Most engines now use some type of hydraulic valve lash adjustor and do not require a periodic valve adjustment service

How It's Done

The technician removes the valve cover(s). Each valve is then checked individually for the proper clearance between the camshaft lobe and the valve itself. The clearance for each valve is adjusted to the proper specification as necessary. Valves that are too "loose" (too much clearance) will cause excessive noise. Valves that are too "tight" (not enough clearance) may not close completely, resulting in valve damage and engine misfires. The valve cover gaskets(s) are commonly replaced when this service is performed.

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