Variable Valve Timing Actuator Replacement
What is a Variable Valve Timing Actuator?
Variable valve timing is used in many engines to increase power and efficiency at different engine speeds. To advance and retard the camshaft timing, the variable valve timing solenoid is used to divert oil pressure to the variable valve timing actuator, and this action causes the variable valve timing actuator to rotate the camshaft in relation to the camshaft sprocket. This actually alters camshaft timing on the fly.
How do Variable Valve Timing Actuators work?
The variable valve timing actuator will typically have the camshaft timing sprocket mounted on one half, and the other half will able to rotate semi-independently of the sprocket. When oil pressure is applied to the actuator, it causes the camshaft to rotate with the independent half, and the camshaft sprocket stays in time with the timing belt. This allows the camshaft to rotate a little further than the timing belt or chain will allow, and this will allow engine valves to change the moment they open to accommodate faster engine speed and higher flow rates.
What are the symptoms of a bad Variable Valve Timing Actuator?
Variable valve timing actuators of all types begin to make noise as they fail. This is a clatter or knocking that is heard on startup because oil pressure is not being maintained by the actuator. Until oil pressure builds, the actuator will clatter or knock, and if oil pressure cannot be retained at sufficient levels, the noise will continue until mechanical failure. Hard starting when the engine is cold is likely of a failed actuator, as is low power at high speeds, but generally not both. The check engine light may illuminate at some point.