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.
Can I drive with a bad Variable Valve Timing Actuator?
The variable valve timing actuator should not be ignored. At first, they give tell-tale signs of failure by clattering, as mentioned, but after a short time the clattering will become worse, and engine failure of some type is possible.
How often do Variable Valve Timing Actuators need replacement?
There are specific vehicles which are known for failure of the variable valve timing actuators, and these may require replacement as early as 5,000 miles. Though recall campaigns have corrected many of these problematic vehicles, failure rates have dropped, not disappeared. Other vehicles not prone to actuator failure are likely to experience failure due to lack of proper oil and engine oil filter changes, hard driving, or a combination of the two.
How are Variable Valve Timing Actuator issues diagnosed?
The variable valve timing actuator noise on startup will be clearly audible from the valve cover. If the actuator is suspected of failure, but the noise from the actuator is not clearly distinguished as a variable valve timing actuator, manufacturer specific testing may be used, or exploration may be required to diagnose the issue.
How are Variable Valve Timing Actuators replaced?
Since these actuators are part of the camshaft timing sprockets, the engine valve covers, engine front cover, timing components, and camshaft sprocket/variable valve timing assembly must all be removed to complete this repair. In many cases, the camshafts must be removed, as well as a camshaft timing chain. Any other components that prevent the removal of these components must be removed as well, and the engine must be properly timed before reassembly. Finally, once installed, the engine will be ran and tested for proper operation free from clatter.
RepairPal Recommendations for Variable Valve Timing Actuator issues
We do not recommend the use of thick oil to quiet the actuator. The oil specified for use by the manufacturer, both type and weight, should be used, and if the clatter exists, the proper solution is repair.
What to look out for when dealing with Variable Valve Timing Actuator issues
The noise made by these actuators are responsible for many engines being replaced, and many timing chain tensioners as well. It is especially important that when the variable valve timing actuator fails, the vehicle should be inspected by a qualified professional prior to replacing parts.
Can I replace the Variable Valve Timing Actuator myself?
Since this requires significant deconstruction of the engine bay, removal and replacement of timing components, removal of precision machined rotating assemblies, and extensive knowledge for performing these operations, this should only be left the a professional technician. There is a great margin of error in these repairs, and it is not worth the risk for the average or slightly experienced DIY to attempt.
