2002, jeep, grand cherokee laredoJanuary 5, 2015engine making knocking noise Keywords:Grand Cherokeeknocking noise 1 thought on “2002, jeep, grand cherokee laredo” Freeautomechanic January 5, 2015 at 9:48 pm If this noise is coming from the top of the engine and it is a 4.0L 6 cylinder, I wouldn’t worry to much about it. This is EXTREMELY common for this particular engine. The noise is from worn valve lifters. It will not hurt the engine to continue to drive it(and I mean for years). Just change your oil regularly and you got yourself a pretty good engine overall. However if the knocking noise is coming from deep in the bottom of the engine, it may be a rod or main bearing(not so common). Main bearings tend to knock louder at idle and disappear as rpms increase. The opposite is true of a rod bearing as it tends to get louder as the engine rpms increase. Comments are closed.