You can find a lot of information and answers to your question on this forum in archives. I have had 2 2018 2500 6.4 CC Rams. The first one was diagnosed with exhaust manifold leaks at 100 miles. The second at 80 miles. However only "some" of the 6.4 2500 have this issue. Most do not and there are fewer in the 6.4 than the 5.7. The cause of the 6.4 exhaust leak is well known. Dealer refer to it as a "factory defect" The manifold bolts are either over torqued or under torqued. This results in a leak between the aluminum head and cast iron manifold. It actually sounds like a serpentine pulley with a bad bushing. Screech/hiss noise on start up. Some also had y pipe leaks. That part now has a new # ending with AD. Believe that leak has been addressed. I have 2200 miles on my replacement 2500. I have ordered the parts that MOPAR tells me I need. My tech will do the repair. I do not trust the dealer techs that are available to us. My tech has corrected a few of these because he follows the factory specs for assembly and tightening. These are excellent trucks, with this one exception. The ones that are assembled correctly tend to not have this issue.
