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Old 11-14-2010, 09:55 PM   #1
Sierra8's Avatar
Join Date: Apr 2010
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3.8L lower end knocking?

I have a very faint knocking sound after my Jeep warms up. It is audible without any load on the motor up til about 2k rpm and then goes away. The knock isn't very loud but is definitely there. I've removed the serpentine belt temporarily for a few seconds to make sure it wasn't any of the accessories and the knock is still there.

I bought my Jeep used at around 44k and have about 53k on it now. The knock hasn't gotten worse but I think it's always been there since I've owned it. Is this maybe piston slap I'm hearing or something else? I also have the clutch pushed down and it doesn't seem like anything with the clutch assembly spinning in neutral. Anyone hear this too or is this maybe something I should worry about? I have an extended warranty up to 125k so I'm not terribly freaked out but I'd like to figure out what's generating the noise.

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Old 11-14-2010, 10:05 PM   #2
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I would DEFINITELY bring it in to get checked out. If it's major, I'd want it fixed BEFORE you get stranded with a popped engine! Mark W.

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Old 11-15-2010, 05:58 AM   #3
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Join Date: Aug 2010
Posts: 179
i have 2 guesses here

either you have had a poorly maintained jeep and there so much sludge built up in the engine that ur not getting enough oil, easy to check take rocker cover off and all check, replace gasket doesnt take to long or

you did the bottom end which means take the 3.8 out throw away and drop a 350 in it
2007 Jeep Wrangler 2DR Sport
33x12.5x16 Mickey Thompson MTZ
3 Inch Lift-Synergy Springs, Fox Shocks, Teraflex Lower Control Arms, Fox steering dampener
Arb Winch Bullbar with 9500lb Winch(dynamo rope)
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Old 11-15-2010, 07:02 AM   #4
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Originally Posted by thaduke2003 View Post
I would DEFINITELY bring it in to get checked out.
There are too many things it could be for an internet diagnosis. From totally benign to catastrophic.
Listen to the Duke and have a trusted mechanic give it a look.

If you're going to drop the oil pan to look for sludge, put one of these on or a skid.

Good luck
Gone camping,

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