You can tell a bad valve by doing a compression test.
how do you know when valve lifters for 94 mercury villager 3.0 engine r bad
It depends on what's tapping. You may have a bad lifter or a valve problem.
A bad EGR valve in a 2000 Saturn can have several symptoms. The EGR valve can cause misfires, the valve can cause vacuum leak style problems. There could also be an engine knock.
it bangs when you put it in gear
The lifter's are all the SAME. the push rods are what is DIFFEERENT. Some are longer the the others. They MUST be put in the right place are you will bend a valve as soon as the engine turns over.
The purpse of valve lifters is exactly what it says, to lift the valve.
no fix for lifter.... must be replaced... remove valve cover, remove rocker arm assembly replace bad lifters.... put it all back together
Check engine lit goes on.
The lifter bucket, which is on top of the valve stem, and the spring in the Overhead Cam engine aides in adjusting the valve clearance.
valve should rattle when shook, and when engine is started it should have a good suction.
If clicking while trying to start then might be a bad starter. If clicking while running, then might be valve/lifter noise.