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Discussion Starter #1
Hello I have a Grand Cherokee and I was wondering if anyone have had this problem in the spring and fall when the temperature is like 68 - 70 getting exhaust fumes smell in the cab strong enough to give me a headache when the AC is on and the dealership never heard of it
 

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Welcome to the Forum, from Cave Creek AZ.
 

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2020 WK2 Limited X
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115 Posts
No, but thats something not to mess around with. Id get a carbon dioxide reader and beeper, put in car. If its inside the car, its dangerous. Have a reputable muffler shop do a full inspection.
 

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2014 GC Limited 4X4
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Possible clogged catalytic converter if I had to guess....
 

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2014 Summit 5.7 4wd 20" tires swapped to 18", added all skid plates
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The intake for the AC/Heater is on the passenger side down below the cowl. If you had a leak in the exhaust manifold or exhaust pipe on that side it might draw in some fumes. But I would think you would hear exhaust noises if that was the case. If you smell fumes but there are no exhaust noises it would seem like it would have to be leaking downstream of the muffler somewhere along the tailpipe. The other thing I can imagine is you have a small oil leak that is dripping on the hot exhaust and what you are smelling is the oil cooking on the hot exhaust and getting sucked into that air intake. It might be more noticeable in this cooler weather because its not recirculating air but is drawing in fresh air thru the intake.
 

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Discussion Starter #6
Oh yeah that makes sense I could check that out i don't see any oil anywhere on a skid plates from up above but I will look closer
Ty
 

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2014 GC Overland
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I didn't see which engine you have but the V8 was known to have issues with exhaust manifold bolts breaking on their own. You can usually hear a ticking noise until the manifold heats up and closes off. A leak from the manifold will be raw exhaust that would contain carbon monoxide. Anything behind the catalytic converter likely won't. Try setting the HVAC to recirculate until you've solved the problem as that doesn't draw in much if any outside air.
 

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Discussion Starter #8
I didn't see which engine you have but the V8 was known to have issues with exhaust manifold bolts breaking on their own. You can usually hear a ticking noise until the manifold heats up and closes off. A leak from the manifold will be raw exhaust that would contain carbon monoxide. Anything behind the catalytic converter likely won't. Try setting the HVAC to recirculate until you've solved the problem as that doesn't draw in much if any outside air.
its a v6 but the funny thing is it does it in the fall and spring but i dont hear any noise from the manifold either
 

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Grand Cherokee
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If you suspect an exhaust leak, always keep the HVAC system into the vent mode, not recirculate mode.

Are you in recirculate or vent mode when you smell the exhaust fumes?

Have you inspected your exhaust system for damage or leaks?

The intake for vent for the HVAC system is at the base of the windshield on the passenger side. There are more than one seal that would prevent leaking exhaust from entering the intake. Might want to inspect those seals.

Finally there are vents for the cabin at the rear of the vehicle under the rear fascia/bumper. They have flapper valves, so they are suppose to let air out, but not in. They are not far from the exhaust. There was more than one post a while ago on this forum, that talked about getting exhaust fumes in the cabin under hard accelleration. And all of them turned to be the flapper valves on the rear vents had something wrong with them. They are simply rubber flaps laying over the opening.
 

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Discussion Starter #10
I checked the exhaust best I could but wouldn't hear something I hear nothing and it does it in recycle or in recycle or vent mode and only happens two times a year spring and fall
 

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Grand Cherokee
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Check your cabin vents, if one of those little rubber flaps has got stuck or broke, that would cause your complaint, even if the exhaust is working perfectly.
 

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Grand Cherokee
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Yes, in the back under the fascia cover of the rear bumper. Get on the ground and look up under the fascia just behind the rear wheels.
 

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Discussion Starter #15
Okay so the exhaust smell I smell is definitely coming from the AC and there's no oil leaks or exhaust that i can tell I looked around the air box intank I dont see how the smell can get in there and why it only happens when its only like 65 and 68 degrees out im at a lost
 
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