I have the exact same problem... Never knew what it was

 

If it is the same sound I had on the Vette, think ice in a blender type sound (maybe slightly less harsh).

 

I have to add that my 08 Rubi unlmtd is a 6spd, not that it matters. I originally thought that mine occurred when the ac was on at startup but then I noticed that sometimes it wasn't ...BUT ac had been on during the previous run. AC on in the morning going to work, ac turned off, Jeep sits for the day and then the rumble grind when I start in the afternoon. I'd also like to say that the noise I hear is a kind of "rough rumbling grind" that last less than a second. Really not so much a metal on metal. Boy, what a description! Sometimes it feels like it's a seized bearing somewhere in the belt serpentine loop that breaks free on the startup and is then good to go for a while. I'm going to jinx myself at this time and say that I have not noticed the noise for a few weeks. It will now come back and haunt me for months!

 

Funny you say this... As I recently posted, I thought this only occurred with my AC on as well, but of course 30 minutes after I said that, I got in my Jeep (which has been sitting for about 2-3 days) and started it up without the AC on and it happened!!

I'm going to call the dealer tomorrow and try to explain what's happening to see if they have any ideas.

My girlfriend was in the Jeep with me and heard it. I asked her to describe the sound and she said it sounded like a fart... but we all know the many sounds a fart can have, so not sure that helps anyone. I'd say it was more of a rrmmph than a sweeakk or puufff...

I'll let ya'll know what the dealer says after I speak with them.

 

I'd say it was more of a rrmmph

Yes, that's it. It's there and gone before you can try and pin it down.

 

I just spoke with three different service departments at Jeep dealers here in Austin and none of them knew or have heard of what I described. They all said they'd have to hear it for themselves.

I'm going to switch to the motocraft oil filter since that's the only solution I've seen/heard for this type of issue.

I'll let ya'll know if it works or not.

 

As an update, I changed my oil filter to a Fram Tough Guard and it's still making the noise. In fact, I got in my Jeep today for the first time in a couple of days and it was louder than it's ever been.

Gonna definitely take it into the dealer... pretty pissed since my Jeep has less than 5,000 miles on it.

 

I get this as well. To my knowledge it only happens when I left the AC on or turned it off after I turn off the Jeep. I use the AC almost year round, as it pulls moisture out of the air in the cabin and defogs the windshield faster. I think that the AC clutch stays engaged when you turn off the Jeep. But mine is definitely AC Compressor related.

 

I have heard this "rumbling" sound since I first got my jeep.
It only makes it after the jeep has set idle for a day or more.
I hate to say it, but it sounds to me like the noise an engine makes before the oil gets on all parts, ie: metal on metal, but very briefly.
A very scary sound.
I have been following this thread with great interest. I'm reluctant to take it to the dealer, as I'm sure it won't make the noise unless I let it sit there overnight, and then it is so brief that most people might not even hear it, and then it won't make it again unless it sits again.
I tend to think that it is a matter of the oil completely settling to the bottom of the engine, and it takes a couple of cranks for it to get back to the top of the cylinders. (hope i'm wrong)
I may be way out to lunch on this, so if anyone can get it to a good mechanic thet has a good ear, I would be very interested in hearing what he thinks it is.
I never use my AC so i have ruled that out. I have less than 1500 km
and have been very gentle breaking in the engine.
Oh, and by the way, I love my jeep, and fully enjoy this forum and all of it's helpful participants.

signed....
I have been

Wrangled

 

Mine does this too. Weather doesn’t matter or A/C being on or off. I figured it was the oil issue like other’s have said when the vehicle sits up for a day or so.