2006 Jeep Grand Cherokee just started making a clicking or rattling noise when starting up. The noise isn't audiable when driving. I've checked the oil level and it is normal. It is time for an oil change, however, still within an acceptable time frame. The car has approximately 62K miles on it.

hydraulic tappets are worn

Your alternator is not charging, thats fine when the motor isn't running but if it is running you are on borrowed time and it won't be shortly. If you need to drive some distance to reach an auto electrican charge the battery up first and use the minimum number of electrical accessories possible while you are driving there.

Your jeep ecu is in need of repair. It has what is referred to as the delayed check engine light problem. If you'll notice, next time you try starting the jeep, it will not start when the check engine light finally comes on, on the dash. The fuel pump will only come on when the ecu finally energizes the relays, and that's when all the clicking starts. Look on ebay for an ecu repair service.

i would 1st check out the front tires to make sure that they are not defective, if tires check out ok, then i would put the jeep on a rack at a garage, and check out all of the front end components, including c. v. joints and the wheel bearings.

Your cataylic convertor is going south thats the rattleing noise eventualy it will clog you may get a couple of years at best but you need to start thinking about replaceing it

you may have a cracked flexplate , this bolts the torque
convertor to the motor , or the bolts are loose.

where is click comming from..clean battery terminals and also check all wires to starter to make sure not loose when in fail mode have someone hold key in crank mode and take hammer and tap hard on starter if it starts replace starter.. if not get back with me

Check your oil level first and make sure its at the correct level. A couple of things, if your guage is going up it's a bad guage/sending unit are easiest checks. If it goes way up while driving you probably have an oil passage blocked somewhere causing the pressure to spike maybe a spun bearing (lower motor). Does it make any rattling/knocking noise? If not I would get it checked out ASAP, low/high oul pressure can lead to severe engine damage/failure.

Check the battery, it sounds like it's flat. Try charging the battery to see if it recovers, but if the battery is about 3 years old or more it is likely to have failed and replacement is the only viable solution.

It sounds like the ignition relay. Meter the relay to see if it is bad.