davyyrowesxj

I have a 1998 jeep grand cherokee Laredo 4.0 180k good oil pressure it has a knocking sound at idle seems to get quite when your on the accelerator but at idle it's noticble idk if it's a rod bearing timing chain flex plate bolts lifter not sure it has a manifold leak but that's only there when it's cold i tryed running to rotella t 15w40 only made it louder i switched it back to 10w30 any advice anything please let know the video was with the 15w40 after my drive home from work Thanks!
https://youtu.be/OSIoELp9uPg

dave1123

Welcome to CF!

First of all, your Youtube link doesn't work. You may have a cracked piston skirt, but the only way to tell is to drop the pan and look for pieces. If it's the flexplate, the knock will change or go quiet in gear and reappear in neutral.

If you want to see what a cracked piston looks like, check out "WJ 4.0 New Pistons" on this forum.