My engine has been making a very distinct tat tat tat sound at idle only. It seems to do it only when the engine has warmed up. If you rev it up above idle rpm it goes away. I listened to the heads using a stethoscope(?) and it can be herd a little better through the right side of the engine over the left. Just changed the oil about 800 miles ago. Level is well within the safe zone. I am not experiencing any preformance problems and my oil pressure is good. I was thinking it may be the timing chain slapping around but figured it couldn't hurt to ask before I spend money I don't have. If it will help to hear the noise I'll get a video of it later today. Thanks in advance guys!

99 Durango 4x4 318, 96K miles, engine is stock.

 

Try a better octane like 87 or better or try a different name fuel.

 

Is the noise at the heads or timing cover? If it is at the heads then something like that is generally a sticky lifter. I've heard a number of ways to combat this but never a good one. These things seem to come and go.

 

I have a tat tat noise too at idle. But I am pretty sure it is my injectors making the tat tat or click click noise. Odd tho, it the injectors are noisier on the passenger side of the engine. Driver side, it is quiet. Don't recall this louder than usual clicking noise. I may have to take it in for a injector cleaning.