Chrysler Repair: LOUD TICKING/HOLLOW NOISE ON COLD START, loose bolt, bolt nut

Question
I have a 2000 Chrysler I'M with just over 100,000 miles on it. I'm hearing 2 different noises when it is first started in the morning. The first noise is a fast ticking noise that lasts for about 4-6 seconds. I hear this sound is normal on a cold start, but I'm just wondering what it is from. The other is more of a hollow/rattle sound that lasts until the car has been running for at least 4-5 mins and is warmed up. The sound starts as soon as the car is started and goes to normal idle, it does this weather I have it in park or neutral or drive. It is a pretty loud noise and sounds hollow, I tried to find where it is coming from but I cannot tell. It does not affect how the car runs or anything, but I would definitely want to try and fix the problem. Any help would be great, thanks

Answer
Hi Joseph,
On the ticking sound, that is probably the sound of several hydraulic valve tappet/lash adjusters that have drained out some oil while the engine has been sitting. It is very common and nothing to be concerned about so long as the sound goes away, which is an indication that the normal repressurization that occurs with the pumping of oil in the valve train as the engine runs is occuring.
On the hollow sound, that might be related to the exhaust system (which has larger diameter thus more hollow pipe sounds) having a loose bolt/nut and allowing a temporary exhaust leak that self-seals as the parts expand as the result of heating up or it could be clamp that holds the system in place is similarly loose. You could start at the exhaust manifold and check all the fittings to find something that is obviously loose, but be careful not to get too aggressive and overtighten a bolt or break one that has been rusted tight. You want to use some finesse in searching an exhaust system noise. An exhaust shop might find it if you left the vehicle early so as to let it cool and then let them listen when they warm it up.
Roland