Im looking at mine off a 1998 4wd 4.3L, and they still roll on the bottom, Im wondering is it ever worth replacing them? It would seem they are always going to roll. Maybe millions of miles.
Seriously, could these ever wear out?

I dont see any expansion on them. Doesnt seem to be a spring of any kind.

The oil comes in from the top where the rod is and there are no holes on the side for them to expand with oil it seems.

What do you guys think about them? Ive got some top end rod noises, and I am trying to figure out what could cause it.
I dont see how the roller lifters could cause it, is it just a worn cam? what else could cause it? its a kadunk noise when manually rotating engine.

 

The hydraulic part of the lifters can go bad. I had a tapping noise on my 94 cougar. Replaced the lifters and the tapping went away.

 

thanks, i realise my confusion on this, i thought the whole tube expanded and contracted and on this one it didnt seem possible,
but its just the inner part at the top that i guess pushes down under engine load,
and yah I can see how that would fail
and i noticed now the small oil hole on the side would allow oil to flow in now