My 6 cyl. has a couple of hydraulic lifters that will not stay up while pushing down on the respective pushrods. This engine has about 60,000 miles on it. Hotrod L. could I just replace the 2 old ones with 2 new lifters. Sounds a little risky to me. I don't even see how the engine even runs as good as it does with this here issue? Yeah with the engine off valve cover off I can push down on # 3 pushrod and # 5 pushrod, all the others don't even move. Maybe its not in the lifters I don't know?