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knockin rod

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Old Jun 24, 2010 | 12:11 AM
  #1  
komodo95991's Avatar
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From: yuba city ca.
Year: 91
Model: Cherokee
Engine: straight 6 4.0 liter
Default knockin rod

Is it hard to fix this problem on a straight 6 4 liter. thanks

Lucas
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Old Jun 24, 2010 | 10:57 AM
  #2  
CAEMI's Avatar
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From: Detroit, MI
Year: 1994
Model: Cherokee
Engine: 4.0
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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.
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Old Jun 24, 2010 | 11:01 AM
  #3  
96_xj's Avatar
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From: Gilbert AZ/Las Cruces NM
Year: 1996
Model: Cherokee
Engine: 4.0 upgraded
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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.
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Old Jun 24, 2010 | 11:02 AM
  #4  
razor02097's Avatar
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From: Ohio
Year: 1998
Model: Cherokee
Engine: 4.0 stock
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If it really is rod knock then yes it is a big, expensive job.

Are you absolutely sure it is a rod?
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Old Jun 24, 2010 | 11:03 AM
  #5  
tannerp89's Avatar
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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
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^^^ 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
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Old Jun 24, 2010 | 01:07 PM
  #6  
C.J.'s Avatar
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From: Lincoln, Nebraska
Year: 2000
Model: Cherokee
Engine: 4.0
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It would be cheaper to find a used complete longblock or shortblock (no head) out of a junkyard than pay to have it rebuilt. Just an idea.
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Old Jun 24, 2010 | 02:15 PM
  #7  
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From: Oroville, CA
Year: 1995
Model: Grand Cherokee
Engine: 4.0 with all of the noise and clatter
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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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Old Jun 24, 2010 | 03:57 PM
  #8  
CAEMI's Avatar
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From: Detroit, MI
Year: 1994
Model: Cherokee
Engine: 4.0
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Originally Posted by Bustedback
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.

Amen. That is exactly what was wrong with mine. Having a real mechanic listen to it saved me a rebuild.
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Old Jun 24, 2010 | 07:45 PM
  #9  
komodo95991's Avatar
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From: yuba city ca.
Year: 91
Model: Cherokee
Engine: straight 6 4.0 liter
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thanks guys.

Lucas
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Old Jun 26, 2010 | 02:09 AM
  #10  
IT'S AN XJ THING's Avatar
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From: KEIZER, OR
Year: 97
Model: Cherokee
Engine: 4.0
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Ya, i had the same problem and thought it was a rod knock. It ended up being the torque conv. Bolts.
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Old Jun 26, 2010 | 12:11 PM
  #11  
milmat1's Avatar
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Year: 2000
Model: Cherokee
Engine: 4.0L
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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 !!
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