creeping noise
Hydraulic lifters are nonadjustable. Chances are the noise is coming from play in rocker arm, or ignition out of time. If you are sure it is the lifter, then it must be replaced.
hydraulic lifter? Rocker arm?
I was taught it was a noise thing - less noise in the hydraulic system due to less tapping of metal on metal. Hope someone reads this and verifies, but that's what I was taught.
Stuck hydraulic lifter.
if ticking noise is in engine, u most likely have a worn hydraulic lifter. check oil for correct volume and viscocity
Noise can cause permanent damage to your hearing. To avoid this danger, use hearing protection such as ear plugs or ear protectors (these look like big headphones).
poo
Could be hydraulic shock (water hammer)
You don't... Hydraulic tappets are fitted. If they make a tapping noise occasionally that goes away get used to it, or add hydraulic tappet cleaner additive to the engine oil after an oil change. If they constantly make the tapping noise it's time to get them checked out. Could be expensive!
Mice make little if any noise when creeping about. Thus, this figurative expression explains that she was very quiet as she moved past the baby.
Collapsed hydraulic valve lifter? Rocker arm (valves) need adjusting?
Collapsed hydraulic lifter? - try a quart of mystery oil