Q: I have valve lifter noise on the right side of my engine.

The lifter is tapping as either the oil pressure to the lifter has dropped or the lifter is sticking from old sludge build up from the mileage. Try changing the engine oil and filter and see if the lifter noise goes away. If the noise is still there. Then add 1 quart of ATF to the engine and run the engine for 15 minutes at 3,000 rpm’s. This will thin out the engine oil and clean out the lifter with the high detergents. Then drain the oil and replace the filter and put new oil in the engine. If the lifter noise is still there, then I recommend replacing the lifter. Since the engine has more than 120K miles, I suggest replacing all of the lifters. If you need further assistance with your lifter making a noise, then seek out a professional, such as one from Your Mechanic, to help you.