engine opinions please

jeepcher4x4 · 11-06-2005, 08:05 PM

I need help my engine has a metal tapping sound. I was told it was a wrist pin by a mechanic. My parents bought me a truck and we have to keep the jeep cause insurance. I am in an offroad club and its going to be trail rig. What should i do as far as an engine and how much $$ my options r gna cost. I have a job. I am only 16. Opinions please

JoBo · 11-07-2005, 04:49 AM

The 4.0 I6 engines are nosey in general but if you have the auto trans the most often cause is the flex plate bolts loosening. Easy cheap fix, use the search function. If it's the engine then it's likely piston slap and that can be helped with a can of RESTORE at every oil change

XJ4oh · 11-07-2005, 10:15 AM

My vote is either for a bad lifter, loose rocker arm, or the flex plate bolts being loose. If you have something else to drive, and this will be a trail rig only.. then either buy a used motor now and drive this one till it blows, or pull the engine yourself and tear it down, and teach yourself how to re-build it.

88Mud · 11-07-2005, 11:13 AM

My piston slap is most noticeable at or near idle and/or when it's cold. I picked up another knock, that got worse as the RPM's went up, turned out to be mostly the connecting rod bearings, I checked them with plasti gauge and they were at the outside allowable measurement. If you check the clearance on the connecting rod bearings, check the top bearing, as this is the one that wears the most.
My top end valve train rattles pretty good but it never seemed to hurt much.
Changing the connecting rod bearings, isn't really that much of a job. And can be done with the motor still in the Jeep.
I use a piece of plastic tubing held to my ear, to localize the sound. Listing in the oil filler hole might tell you if it's in the top.
I've never heard anybody else mention wrist pins as a trouble spot. But heck anything is possible.