Why does my Jeep Fart???

GregB · **Posted:** Mon Jan 22, 2007 11:56 pm

I know it's crude, but there's really no other way to describe it. 3 times in the last 30 days the KJ has made a noise best described as a 'fart noise'. It is relatively soft, about 1-1.5 seconds long, and kind of a trumpet like sound to it ... a short low 'D' note if you will.

Anyway, I have no idea where it's coming from. I'm having no luck recreating it (yes yes ... insert your bean joke here). Twice I heard the noise while driving in a strait line at a constant speed, once I 'think' I heard it while the Jeep was off and parked in the garage. Does anyone have any serious ideas of what this might be before this topic goes too far down the wrong path?

2006KJSPORT4x4 · **Posted:** Tue Jan 23, 2007 12:24 am

did you happen to be using your air controls whenever this noise would occur....or do you leave your air on even after you turn the jeep off?

FastTRX · **Posted:** Tue Jan 23, 2007 1:27 am

Whoopee Cushion wedged in one of the springs?? :lol:

I'm sorry but I had to say it...

Very wierd...thats definitly a new one!

What fuel are you feeding it? Your KJ must have bad gas! :lol:

Sorry...didnt mean it that time! lol...just came out that way.

Great thread...haha

GregB · **Posted:** Tue Jan 23, 2007 9:57 am

2006KJSPORT4x4 wrote:

did you happen to be using your air controls whenever this noise would occur....or do you leave your air on even after you turn the jeep off?

I probably had the heat on the lowest fan setting. I know those fan can make a funny hum when they are cold, but this was a short burst from out of the blue.

A friend of mind said a lot of GM's will make strange noises when the exhaust system and heat shield get hot. The metal will expand and pop, and a pop with some vibration could produce the sounds I've heard. I'm not so sure I buy into this explanation, but it's probably the best explanation I've got so far.

For the jokers out there, the first time I heard the noise I blamed my wife and my wife thought it was me. I didn't realize it was the jeep until it happened and it was just me inside. Maybe my KJ is a big fan of crude fart jokes? The KJ is about 5 years old and I know I liked fart jokes when I was 5 :wink:

sleeve84028 · **Posted:** Tue Jan 23, 2007 12:06 pm

Does it happen with the A/C cycling? Under acceleration, or normal cruise?

If it was high pitched enough I would tend to think the belt

Spike6901 · **Posted:** Tue Jan 23, 2007 1:37 pm

Mine has alwayse done it and I never did figure it out. Maybe it is bleeding off pressure from the fuel system? Don't know.

GregB · **Posted:** Tue Jan 23, 2007 1:37 pm

Wasn't very high pitched, but I suppose it could have been a short slip of a belt as something like the compressor engaged. I haven't been able to recreate it. If I hear it again I'll be sure to note exactly what I was doing a report back here.

Bakerkj · **Posted:** Tue Jan 23, 2007 1:43 pm

What does it smell like?

sleeve84028 · **Posted:** Tue Jan 23, 2007 2:20 pm

Bakerkj wrote:

What does it smell like?

spent gas?

Jeepjeepster · **Posted:** Tue Jan 23, 2007 3:18 pm

GregB wrote:

Wasn't very high pitched, but I suppose it could have been a short slip of a belt as something like the compressor engaged. I haven't been able to recreate it. If I hear it again I'll be sure to note exactly what I was doing a report back here.

If it does it again, check to see what postition the air is on. If its on defrost, the A/C can kick on. Ive heard my belt makes noises when the A/C kicks on.

TheJawsOfDeath · **Joined:** Sun Nov 05, 2006 3:56 am **Posts:** 305

Something kind of similar happened to mine. When I was installing a line out converter to run my subs from the factory deck I had to get everything o ut of the way so I disconnected the vac. lines from the HVAC control, the middle one that controls which vents blow. after getting it back together, it made this weird soft honking noise when switching from vent to vent at first. but it went away. definately more of a soft honk than a quiet fart though, lol.

Blue KJ in PA · **Posted:** Tue Jan 23, 2007 5:55 pm

I just switched out my 03 HVAC for an 04 HVAC control. When I unhooked the vacuum tube harness I heard a noise from the depressurization of the lines which could be construed as a soft fart. When I hooked up the new one and started up the engine I heard similar noises until every line repressurized. Maybe you have a vac hose that is not tight to the rear of the controller or has a leak.

GregB · **Posted:** Tue Jan 23, 2007 8:08 pm

Well, I tried playing with the climate controls for 15 minutes trying to recreate the noise, but no luck. Until I can isolate where the noise is coming from or figure out a way to recreate it, this will remain a mystery.

Anyway, it's very infrequent. If it continues or gets more frequent I'll have to do some more asking around. If anyone else has any other ideas or similar issues, please drop a line. Right now my best gues is some kind of vapor leak or belt noise, but I really don't have a clue on this one.

TheJawsOfDeath · **Joined:** Sun Nov 05, 2006 3:56 am **Posts:** 305

Blue KJ in PA wrote:

...I heard a noise from the depressurization of the lines which could be construed as a soft fart.

not to be immature but i nearly fell out of my chair laughing when i read that "could be construed as a soft fart", this has to be the funniest thread ever. :lol:

Donkeykong · **Posted:** Wed Jan 24, 2007 7:07 pm

TheJawsOfDeath wrote:

Blue KJ in PA wrote:

...I heard a noise from the depressurization of the lines which could be construed as a soft fart.

not to be immature but i nearly fell out of my chair laughing when i read that "could be construed as a soft fart", this has to be the funniest thread ever. :lol:

Dude, fart jokes are a right of passage.

Seriously though, did you happen to notice if the sound was coming from the dash, center console or where?

Maybe you have a barking spider infestation?
-Mark

TheJawsOfDeath · **Joined:** Sun Nov 05, 2006 3:56 am **Posts:** 305

my farting noise was coming from the drivers seat...

no seriously though, the HVAC vac line noise was just from the inside/middle of the dashboard.

GregB · **Posted:** Wed Jan 24, 2007 8:00 pm

Quote:

Dude, fart jokes are a right of passage.

Seriously though, did you happen to notice if the sound was coming from the dash, center console or where?

Maybe you have a barking spider infestation?
-Mark

Like I said, at first I thought it was my wife. I caught a lot of hell for that. Anyway, hard to tell if it came from inside or under the cabin. Don't think it came from under the hood. And for those who have asked or were thinking, no smell.

GregB · **Posted:** Wed Jan 24, 2007 9:11 pm

TheJawsOfDeath wrote:

my farting noise was coming from the drivers seat...

no seriously though, the HVAC vac line noise was just from the inside/middle of the dashboard.

The wife says she thought it came from under the seats or under the jeep.

Now when people ask me how much gas a KJ eats I can reply, "It doesn't eat gas, it passes it."

GregB · **Posted:** Sun Mar 18, 2007 11:47 am

Well, Feb was relatively quite, but old KJ is tooting a couple times a week now in March. What we've figured out:

- Turning or driving strait doesn't matter, so it's not "power steering honk"

- It has tooted with all the climate controls in the off position, so probably not HVAC. Plus I've had a car that made noises in the HVAC lines, this just sounds like it's something different.

- It has tooted while stopped in traffic at a red light, so it would seem it has nothing to do with forward motion.

- I have never heard it toot at highway speeds. (could be that loud road noises or radio drowns it out, but I haven't heard it.)

- As far as location, all I can say for sure is that it comes from outside the cabin. My wife thinks from under the hood, I think either under the hood or under the front half of the vehicle.

My mechanic gets a good laugh every time I talk to him about this. Since I had told him over the phone about how we were stopped and it made the noise, his best guess is that it's coming from a vac in the brake lines or some diaphragm in the brake system. He asked me if we were using the brakes every time it toots, but I can't say for certain that's the case.

My best guess is that something gets hot, like a heat shield, and the metal pops in a funny way, like when you hit a dent out of the bottom of a metal mixing bowl. This could explain why I don't hear it on the highway. Airflow would keep things cool. Anyway, popping metal can make some funny sounds, but I'm not sold on this yet because it sure sounds like it's leaking some kind of vapor.

Donkeykong · **Posted:** Sun Mar 18, 2007 12:37 pm

On that same path of logic, I would venture to guess that maybe a check valve isn't operating properly? Especially if your mechanic is asking about your brakes being applied at the time....
I remembered this quote and think about it every time I hear my trunk latch it's self when I am backing out of my garage. :lol:

-Mark

Why does my Jeep Fart???

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