knockin rod
Senior Member
Joined: May 2010
Posts: 889
Likes: 2
From: Detroit, MI
Year: 1994
Model: Cherokee
Engine: 4.0
Yup. You rebuild the motor...with a new rod...and re-ground crank journals...and oversize bearings.
But the good news is that if they're aren't too many miles on it, you might not need new pistons.
It's a big job no matter how you slice it.
But the good news is that if they're aren't too many miles on it, you might not need new pistons.
It's a big job no matter how you slice it.
Honorary Moderator
Joined: Mar 2010
Posts: 8,135
Likes: 16
From: Gilbert AZ/Las Cruces NM
Year: 1996
Model: Cherokee
Engine: 4.0 upgraded
x2
as long as it does not sound like diesel and you have good oil pressure and compression in the cylinders i would just leave i alone.
as long as it does not sound like diesel and you have good oil pressure and compression in the cylinders i would just leave i alone.
CF Veteran
Joined: Jan 2010
Posts: 1,316
Likes: 1
From: Coeur d' Alene, Idaho
Year: 1998
Model: Cherokee
Engine: 4.0 rebuilt w/ bored TB, banks header, upgraded ignition, 3 row rad, high flow h2o pump, 180* t-stat
^^^ he's right, rod knock = rebuild.
how bad depends. you might get away with new rings and bearings, and not have to turn your crank. or your Cylinder walls could be muffed and youll need to bore, which means new pistons too....
if it was me i would drop your oil pan and inspect your rotating assembly, see if i could anything out of the ordinary..
or start looking for a engine to rebuild
how bad depends. you might get away with new rings and bearings, and not have to turn your crank. or your Cylinder walls could be muffed and youll need to bore, which means new pistons too....
if it was me i would drop your oil pan and inspect your rotating assembly, see if i could anything out of the ordinary..
or start looking for a engine to rebuild
CF Veteran
Joined: Feb 2010
Posts: 12,367
Likes: 23
From: Oroville, CA
Year: 1995
Model: Grand Cherokee
Engine: 4.0 with all of the noise and clatter
Check the torque converter bolts and make sure the flex plate is not cracked. Those two items will make a rod knocking kind of noise.
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Senior Member
Joined: May 2010
Posts: 889
Likes: 2
From: Detroit, MI
Year: 1994
Model: Cherokee
Engine: 4.0
FIRST BE CERTAIN WHAT IT IS !!!
It takes a trained Ear to diagnose engine noise just by listening to it. And even then it's still a geuss !
At Idle does it have a Steady Tink tink tink.. Or Does it knock under load, or (If its a rod) It should be loudest when cruising at a steady speed when your just "Floating" The engine.
I think these motors are more prone to Main bearing noise than anything else. And like was said above it could be simply something Loose.. Noises are hard to pinpoint in a cast iron engine due to the ringing of cast !!
It takes a trained Ear to diagnose engine noise just by listening to it. And even then it's still a geuss !
At Idle does it have a Steady Tink tink tink.. Or Does it knock under load, or (If its a rod) It should be loudest when cruising at a steady speed when your just "Floating" The engine.
I think these motors are more prone to Main bearing noise than anything else. And like was said above it could be simply something Loose.. Noises are hard to pinpoint in a cast iron engine due to the ringing of cast !!
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