While adjusting my valves I notice that the #1 piston Exaust lifter is acting wierd... When I put the push rod on it I can push the rod down a little bit about 1/8" or less and it pushes back up... It feels kind of "spongy" Is this the enternal spring that is giving and pushing back.... I felt the other lifters to see if they did the same thing and they all feel pretty solid. What is wrong with this picture if anything at all?

 

It could be a hydraulic lifter going bad.

 

Any other opinions would be greatly appreciated.......