Classy Comanche Posted May 21, 2023 Share Posted May 21, 2023 I noticed recently I have a different noise coming from my engine. I know it isn't rod knock because it would knock at idle, acceleration and deceleration. It sounds like a very light knock sound at idle. I have lifter tick. So when I accelerate I can hear the ticking speeding up or slowing down/idling. Would this light "knock" sound be piston slap? It almost seems like it disappears when the engine is at optimal temperature. I do not have a audio clip right now. I do apologize but has anyone experienced this, know what it is? The sound also goes away when I start to give it some throttle. Link to comment Share on other sites More sharing options...
AZJeff Posted May 21, 2023 Share Posted May 21, 2023 A stethoscope will help you isolate the location of the noise in the engine. Some of the conditions you describe sound like pistol slap might be the source. Since the 4.0 engine uses pretty short skirts on the pistons, and this can contribute to creating slap. That said, slap, while annoying, can exist for many thousands of miles without any significant issues. A compression test can help to determine if the piston to bore clearance is just enough to create slap, or bad enough to lead to oil consumption issues, etc. Link to comment Share on other sites More sharing options...
cruiser54 Posted May 22, 2023 Share Posted May 22, 2023 Ever snugged up your flexplate to torque converter bolts? I consider that preventive maintenance. https://www.cherokeeforum.com/f51/how-fix-flexplate-knocking-125547/ Link to comment Share on other sites More sharing options...
Classy Comanche Posted June 16, 2023 Author Share Posted June 16, 2023 So I'm coming back to this thread. The noise your hearing is the truck idling in park. I give it some gas and this is the "knock" I speak of. I have not taken any action on it as I don't know what it could be. It seems to be coming from the bottom end? It's not rod knock...I don't think. But you guys can certainly hear. I know these 4.0's are noisy. It has plenty of oil. Only has like 1500 miles on said oil. My phone is placed right beneath the engine close to the oil pan. I also started noticing this not long after I had my new muffler put on. Is it a back pressure thing possibly or is this totally normal? It does also seemingly disappear after a short drive 20230615_223831.mp4 Link to comment Share on other sites More sharing options...
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