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Old 04-18-2006, 08:21 PM   #1
PyroParaPig
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Thumbs up 4.0 Knocking Noise UPDATE!

OK. So I have this 92 XJ with 232K miles on it. The 4.0 runs solid, oil has no shavings or metal in it yet I got this knock that sounds a lot like a rod knock. It is present when at idle and no load. As soon as I put it in gear while stoped (torque on drive line) it is gone. Under acceleration, no knock. While decelerating or coasting, knock. It keeps the same pitch but changes speed with engine. My 93 XJ did the same thing but not as loud. My daughters 94 YJ does it but not as loud. It definitley sounds like it is from low in the engine or front of tranny (but most likely engine). Anybody have any ideas on what the heck is it?

SEPTEMBER 18, 2006 UPDATE. OK, so I have been told everything from wrist pin to piston slap to rod knock to main bearing spun to thrust bearing wiped and the cranck was hitting the block. I was told to drive and don't worry about it to turn it off right now before a destoy anything left of value. This came from those who have heard the noise to the forums here where you were at a disadvantage and could not actually hear the noise. No I am not pointing fingers because I didn't have a clue either.

A friend of mine told me to check the torque converter bolts. So finally after months of listening to it growl like a cement mixer I decided to do just that. I recently installed a lift at my shop and put this bad boy up in the air. Removed the inspection cover and what do I find? ALL FOUR TORQUE CONVERTER BOLTS LOOSE! One was backed out a full revolution, one about a half revolution, and the other two half turn or so. So a quick tightening with my handy dany Craftsmen wrench, lower the beast, crank'r up and what do I hear?......nothing but the sweet purr of 235,000 miles of 4.0. No knocking, rattles, no sounds of engine jumping out of the engine compartment. The Cummings diesel sound is gone and I now have a renewed faith in my 4.0. The best thing is I now have $2k to put into other mods and not an engine rebuild.
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Old 04-18-2006, 08:38 PM   #2
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Wrist-pin or piston slap
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Old 04-18-2006, 08:42 PM   #3
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Normal....
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Old 04-19-2006, 05:55 AM   #4
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I am starting to believe it is normal but what the heck is it, crank shaft endplay, smog pump, widget attached to the do-hickie?
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Old 09-18-2006, 06:13 AM   #5
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Default UPDATE! 4.0 KNOCKING HAPPY ENDING!

OK, so I have been told everything from wrist pin to piston slap to rod knock to main bearing spun to thrust bearing wiped and the cranck was hitting the block. I was told to drive and don't worry about it to turn it off right now before a destoy anything left of value. This came from those who have heard the noise to the forums here where you were at a disadvantage and could not actually hear the noise. No I am not pointing fingers because I didn't have a clue either.

A friend of mine told me to check the torque converter bolts. So finally after months of listening to it growl like a cement mixer I decided to do just that. I recently installed a lift at my shop and put this bad boy up in the air. Removed the inspection cover and what do I find? ALL FOUR TORQUE CONVERTER BOLTS LOOSE! One was backed out a full revolution, one about a half revolution, and the other two half turn or so. So a quick tightening with my handy dany Craftsmen wrench, lower the beast, crank'r up and what do I hear?......nothing but the sweet purr of 235,000 miles of 4.0. No knocking, rattles, no sounds of engine jumping out of the engine compartment. The Cummings diesel sound is gone and I now have a renewed faith in my 4.0. The best thing is I now have $2k to put into other mods and not an engine rebuild.
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'01 TJ 2" Skyjacker polyurethane spring spacers, 1" Daystar body lift, 32X11.50X15 Pro Comp All Terrains on Pro Comp Rock Crawler wheels. Nate's custom front and rear bumpers, loose nut behind the wheel. So much work so little money!

www.liberty-cigar.com
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Old 09-18-2006, 07:10 AM   #6
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Quote:
Originally Posted by PyroParaPig
OK, so I have been told everything from wrist pin to piston slap to rod knock to main bearing spun to thrust bearing wiped and the cranck was hitting the block. I was told to drive and don't worry about it to turn it off right now before a destoy anything left of value. This came from those who have heard the noise to the forums here where you were at a disadvantage and could not actually hear the noise. No I am not pointing fingers because I didn't have a clue either.

A friend of mine told me to check the torque converter bolts. So finally after months of listening to it growl like a cement mixer I decided to do just that. I recently installed a lift at my shop and put this bad boy up in the air. Removed the inspection cover and what do I find? ALL FOUR TORQUE CONVERTER BOLTS LOOSE! One was backed out a full revolution, one about a half revolution, and the other two half turn or so. So a quick tightening with my handy dany Craftsmen wrench, lower the beast, crank'r up and what do I hear?......nothing but the sweet purr of 235,000 miles of 4.0. No knocking, rattles, no sounds of engine jumping out of the engine compartment. The Cummings diesel sound is gone and I now have a renewed faith in my 4.0. The best thing is I now have $2k to put into other mods and not an engine rebuild.

Cool, I'll add this little bit of maintanence to my list.
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