The engines of yesteryear were pretty simple, with tappets clackity-clacking away on cam lobes, opening valves, and making a ruckus while doing it. Mechanical lifters were adequate for valve operation ...

"Bullwinkle, that trick never works. Why don't you figure out how to make hydraulic roller lifters survive big spring pressure." "Huh?" Like Bullwinkle, hydraulic roller lifters get no respect. It ...

It's an easy enough problem to prevent. Ignore it and you might as well toss the whole truck in the trash.