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Discussion Starter · #1 ·
I am looking for advice from anyone who might have heard what I'm going to attempt to describe below. I had a post all typed up that was longer, but my wifi router crapped out! Bear with me as I try to relate what I hear to the written word...

Recap: I bought a 2008 Jeep Wrangler with the 3.8 last week. It has just over 35,000 on the odometer. When I bought it, all was good. No weird noises or any other indicators something might be wrong. My wife drove the Jeep for a couple of days, and in preparation for a road trip to TN she is taking, I decided to change the oil. I don't know what the engine had in it, so I decided to use 5W-30 full synthetic and a Wix filter. I checked everything after the change and it seemed fine.

My wife drove the Jeep the next day and put maybe 50 miles on the new oil change. That night, after driving it home, she tells me the engine is making a strange noise. I check it out, and sure enough, there is what I can only describe as a chugging sound. It seemed as though it might be coming from the front of the engine. Since the only thing I did was change the oil, I figured maybe somehow the 5W-30 synthetic wasn't agreeing with the engine, so I did another oil change. This time I used 5W-20 dino oil and a Mopar filter. I did not hear the noise at first, so I thought I found the cause. But, today, after driving it for a while, the noise is back.

I investigated the sound more closely. I discovered in addition to the chugging sound, there is also what sounds to me like drumming on the oil pan. If I apply light pressure to all the four sides of the pan, I am able to make the sound stop when I touch the driver's side of the oil pan. I cannot tell if the chugging sound in the front stops because I'm laying underneath the Jeep. But, the drumming sound most definitely silences when touching the left (drivers side) of the pan. What is weird is that I don't "feel" anything rapping on the side of the oil pan. The sound just stops when I apply a light touch to it.

Both of these sounds cause me some concern. I don't know if they are related, or if they are serious. I am planning to take the Jeep to the dealer to see if I can get a better diagnosis, but I wanted some input from the forum first. Can anyone provide some help to me? I apologize for lack of better descriptive words! I can try to clear it up in the remarks if possible.

Thanks!
 

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Discussion Starter · #2 ·
One more thing... the drumming from the pan is only heard when I lay under the Jeep. It isn't heard when standing next to the Jeep.

The chugging sound heard from the front seems to be coming from the passengers side. I can't quite locate the sound. Seems loudest near the air intake tube area.
 

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Just a heads up : These 3.8L engines may or may not use oil, some use lots of it.
Could be the PO did not check the oil and ran it dry...
Is this a Stick or Auto ? Could be a bad Thrust bearing on the mains if its a stick.
If you take it to the dealer, Good luck ! "BH"
 

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Discussion Starter · #4 ·
Just a heads up : These 3.8L engines may or may not use oil, some use lots of it.
Could be the PO did not check the oil and ran it dry...
Is this a Stick or Auto ? Could be a bad Thrust bearing on the mains if its a stick.
If you take it to the dealer, Good luck ! "BH"
Thank you for the reply. I bought the Jeep from a dealer, so I don't know what the PO did or didn't do. I know this, the Jeep didn't make any noise when I bought it or for a few days afterward. Not until I changed the oil. I put the required 6 quarts in it and the next day my wife heard the noise. I checked the oil right then and it was fine. Since it only had 50 miles or so on the oil, it looked new still. Yet, I did another oil change using the recommended conventional oil. Noises are still present. And, to answer your question, it is an automatic.

I'm hoping it is all in my head. Or, something loose. I've read about some exhaust manifolds getting loose. I suppose before going to the dealer I will give a stethoscope a shot and check the torques on the components. I will also take off the drive belt and see if it stops.

I was hoping someone would know. The numerous threads and videos bouncing around aren't making me feel any better!

Oh, not sure I mentioned it, but the noise isn't present right away. Takes a few minutes before I hear it.
 

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I've got a 2008 with 32k on the odometer that I recently switched from 5w-20 dino oil and Mopar filters to Napa 5W-30 full synthetic and a Napa (Wix) Gold filter and mine actually *seems* to run smoother. I didn't think I would notice any difference and then was surprised when it *seemed* to run quieter and smoother.

So I'm not sure your oil is the issue. I have also been closely watching the oil consumption because of issues with some 2008s. So far no oil consumption.

2008s are also known to spin rod bearings if they are run hot a lot. Not saying this is the issue, but something to keep in mind.

+1 on the stethoscope idea. Check the water pump too.

Did you get any kind of warranty from the dealer? Perhaps a 30 day warranty?
 

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Discussion Starter · #6 ·
2008s are also known to spin rod bearings if they are run hot a lot. Not saying this is the issue, but something to keep in mind.

+1 on the stethoscope idea. Check the water pump too.

Did you get any kind of warranty from the dealer? Perhaps a 30 day warranty?
The bearings are what has me the most concerned. I'm spending far too much time stressing about this, watching videos, and reading threads. I have an appointment Tuesday at the Jeep dealer to have them look at it. In the meantime, I am going to check with the scope and also, drop the oil pan. I've watched some videos of people finding play in the bearing caps, so I will check those.

I'm hoping this is more of the garden variety lifter noise I keep hearing about. Perhaps the noise is resonating down through the left side of the pan and that is why I can muffle it by just applying light pressure to the pan. It does sound as though the noise is coming from higher up (above the pan) when I am laying underneath.

I appreciate those who have replied. I will update this when I find out more.
 
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