I have a 2000 5.4 - the lifters were ticking bad on the front passenger side. After about 4 oil changes and every wonder cure in a bottle I could pour in - I replaced all the lifters and plugs. The motor has 178,000 miles. It was not a hard job to replace these. Got it all put back together and after about 35 miles - the ticking started back lightly at first and then by 70 miles it was a loud whacking sound. I let it sit over night and the next morning started it up and the whacking was still there - pulled it around the house to take
the valve cover off and in just 40 yards of travel the ticking went away. Drove it around for another 15 miles or so and only after letting it sit ideling for 40 minutes it started whacking again from the same area as the original whack - front part of passenger side. Pulled the valve cover off - nothing obviously loose or broke or scarred anywhere. There was a small scratch on the second and third lobe of the cam but nothing that could be felt - just seen. Pulled the second and third lifter and rocker out - thank goodness for the 32.00 dollar tool - rolled them around and they seem fine. (when we replaced the lifters we did them one at a time making sure we did not mix up the rockers) Started it up with the valve cover off to see if we could see what was whacking and you guessed it - it was purring like a kitten - a kitten I'm ready to put a bullet in!!!!!!!!!!! Valve cover is still off - any suggestions as to what is causing the intermiten whacking sound like the lifter. I am running 5w20 in it but with all new lifters in it would it matter or even quieten it down going to a heavier oil - they are new lifters. HELP HELP HELP