A sticky valve lifter is often first heard as a ticking noise in the upper part of the engine under the valve cover. Ticking valve lifters are usually caused by engine deposits. So to unstick a valve lifter, you must clean it. Cleaning a valve lifter can be done in a variety of ways. Follow the steps below to quiet that lifter and get your engine running its best.
Run an engine detergent in your gasoline, and use a higher-octane gas. Often, fuel system cleaners or detergents can free up engine debris and stop a valve lifter from ticking. This often works as quickly as one tank of fuel.
Use an engine flush, and then change your oil. Engine flush products are available at many auto parts stores. Most do not recommend that your run your engine long with the flush in, as it loosens debris and can clog oil filters and thin oil, decreasing its protection. Once you have followed the directions of the engine flush, change your oil and filter. Run your vehicle for about 500 miles, using higher-octane detergent gasoline, and change your oil and filter again. This is often all that's necessary to free a stuck valve lifter.
Remove the valve lifter, and physically clean it. Remove the valve cover. Test each rocker arm. The lifter that is stuck should tick under the rocker arm. Loosen the rocker arm bolt and remove the lifter. Fill a small cup with penetrating oil and soak the lifter in it, preferably overnight. Reinstall the lifter and torque the rocker arm to the correct specification. Install the valve cover, using a new gasket. If this procedure does not work, the valve lifter should be replaced.