2002 Jeep Wrangler lifters hyd.

Most likely the lifters have varnish buildup inside and have frozen. However a lifter must be replaced if the bottom face is concave; use a straight edge to measure this (If they are concave you might need to use a dial guage to check lobe lift on the cam). You will need to remove the cylinder head to gain proper access to the hydraulic lifters. A lifter removal tool makes the process much faster and easier since varnish buildup can really make the lifters hard to remove. If you need a full explaination from start to finish let me know.