Is it loudest during cold starts? If so, it could be lifters but these are solid lifters that are called bucket type. They don't get pumped up with oil like a hydraulic lifter. This is not extremely serious but should be taken care of because it can cause the valve to hang open and cause a performance issue.
However, the rattle/tapping noise that you need to be aware of especially on a used engine where you don't know the repair history is, timing chain guide rails and tensioner that wear out. This will eventually fail and more then likely you will need to replace the engine again.
Infinity has updated these components so it is important that if these are replaced that the updated components are used. Basically, the way to make sure they are the new parts is to buy new ones and not use ones out of another engine.
Here are some videos of what this noise sounds like. Please be aware that the noise is the only thing I am showing you on these videos. The video of the first gentlemen who says this noise is a lifter, is wrong. It is a timing chain guide and tensioner.
Please let me know know if you need more assistance. If you want to do this yourself, let me know and I can send you the procedure for either the tensioner/guides or the lifters. I am not sending it now just because it will be about 20-25 pages so I didn't want to send it if you didn't want it. Thanks
Sunday, May 5th, 2019 AT 7:28 PM