I've been trying to run down an odor on my Denali for about 1.5 years. It's got 178k miles and is otherwise in incredible shape. At this point I've all but given up - I got a newer Yukon XL 2500 and listed the '01 for sale. But this has been bugging me so much, I'd love to figure it out. Hell, I might keep the old truck if I fix it.
The symptom: an odor in the cabin. It has elements of exhaust, burned oil, maybe a tiny amount of coolant.
When it happens: when running the vehicle, especially at highway speeds, when doing a cold start when the engine has been off for about a week.
When it goes away: when I open the windows. When I use the vehicle regularly. It almost seems like there is some seepage somewhere, that only happens when the engine is cold. When I fire it up something expands (stopping the leak) and the odor eventually goes away (after something has been burned off).
Related symptoms: On a cold start after the engine has been off for about week, it runs rough (makes a growl/grunt) for about half a second.
It's not the exhaust manifold gaskets, those were recently just replaced (completing with welding out broken bolts). There doesn't seem to be any exhaust leaks (several mechanics agree).
A cracked vacuum hose was repaired recently, maybe there are more? I see some oil by the front driver wheel, maybe it's the PCV that needs attention?
I wonder if it's the fuel pressure regulator? One mechanic thought this would explain the very brief rough start. It could be the fuel pump of course.
Possibly related: I think one of the clutches in the front LSD is bad. If I drive for an hour at highway speed, then cut the steering wheel (like, say, to pull into a parking spot), the LSD locks and I get tire chatter. My wife thinks it's super scary!
The symptom: an odor in the cabin. It has elements of exhaust, burned oil, maybe a tiny amount of coolant.
When it happens: when running the vehicle, especially at highway speeds, when doing a cold start when the engine has been off for about a week.
When it goes away: when I open the windows. When I use the vehicle regularly. It almost seems like there is some seepage somewhere, that only happens when the engine is cold. When I fire it up something expands (stopping the leak) and the odor eventually goes away (after something has been burned off).
Related symptoms: On a cold start after the engine has been off for about week, it runs rough (makes a growl/grunt) for about half a second.
It's not the exhaust manifold gaskets, those were recently just replaced (completing with welding out broken bolts). There doesn't seem to be any exhaust leaks (several mechanics agree).
A cracked vacuum hose was repaired recently, maybe there are more? I see some oil by the front driver wheel, maybe it's the PCV that needs attention?
I wonder if it's the fuel pressure regulator? One mechanic thought this would explain the very brief rough start. It could be the fuel pump of course.
Possibly related: I think one of the clutches in the front LSD is bad. If I drive for an hour at highway speed, then cut the steering wheel (like, say, to pull into a parking spot), the LSD locks and I get tire chatter. My wife thinks it's super scary!
