chevysuburban2000

Hi all - I acquired a 2000 Chevy Suburban as a hand-me-down last fall. I am using it now as a tow vehicle for a newly-acquired travel trailer. A few weeks ago after picking up said travel trailer I drove it back home about 200 miles.
During the trip I constantly smelled what I can only describe as a natural gas or propane smell in the cab. It's definitely not gasoline fuel.
I took the vehicle into the dealer and they were not able to locate or reproduce. They didn't try the vehicle while towing so they obviously didn't have the same reproduction environment. I still think they should have been able to diagnose or have experience with this, no?
This only happens when I am towing the trailer, which is 3,500 pounds dry. This also happens while in tow/hauling mode and not in tow/hauling mode while towing the trailer.
I took the trailer out again this past weekend and the smell is still very much there.

Does anyone know what's going on? What do I do next? The smell is pretty obnoxious and can't be good for the lungs!
Thank you very much

3Js

Is it a rotten egg/sulfer smell?
Might have your catalytic convertors checked. see if they are getting hot when towing

chevysuburban2000

No it's definitely not a rotten egg smell. Someone on Facebook conjectured it may be the smell of burning transmission fluid.

repairman54

Burning trans fluid would smell like oil burning.
Check the rear door seals, with trailer behind it may be pulling in exhaust fumes as air flow out back is disrupted by the trailer.
Properly functioning clean cats under load do not always smell like sulfur or rotten eggs.

3Js

Pull your trans dipstick and see if the fluid is dark/burnt/smells.

Natural gas and propane have a sulfur/rotten egg smell added to them.
One sign of a malfunctioning catalytic converter is that same smell.

"Among the symptoms of a bad catalytic converter are:

• Sluggish engine performance.
• Reduced acceleration.
• Dark exhaust smoke.
• The smell of sulfur or rotten eggs from theexhaust.
• Excessive heat under the vehicle."

Rednucleus

Silly idea - how about propane leaking from the trailer and being drawn in to your cab.

hanky

We can only go by your experience regarding what you describe as a propane exhaust.odor.

Having worked with both gasoline and propane fueled engines the exhaust "smell" is "distinctly different"

Something you might notice, flies love the smell of propane and that was the first thing I noticed when there was a propane leak.
Hoses for carrying propane are porous to allow pressure inside a leaking hose to escape without blowing the hose entirely.

If,,,,,,,,,,,your trailer has a propane tank mounted on the front, remove it/them and see if you still get that odor when towing , that should eliminate that possibility.

chevysuburban2000

Thank you all for the observations, questions, and ideas. I thought the same thing on the propane tanks on the trailer but they are brand new and I don't smell propane while I'm camped up. I would think if there were a leak then I would smell propane at other times. And honestly I *think* it's a natural gas smell rather than propane. The seals is an interesting idea... maybe exhaust is getting sucked back into the cab. I will take a look at the transmission fluid dipstick and report back.
Thanks!

tech2

schedule a test drive with the shop foreman; for you and the trailer. just tell them you want him to ride with you.

chevysuburban2000

I was thinking that too. Just a nuisance but likely required.