Smoke or Steam from the engine bay

Wirelessguy · 2026-09-22T09:47:43-0500

Before I drop my truck off at the dealer—only for them to hold it for a week and hit me with "No Trouble Found"—I figured I’d ask here first.

I recently noticed smoke or steam coming from the engine bay, visible near the windshield vents when I come to a stop. It happened last week on a drive from St. George, UT to Deadwood, SD, and again yesterday after driving to the Vegas airport.

It's not a huge amount, and it smells neutral rather than like something burning, which makes me think it might be steam. The parking garage was too dark to get a good look, but coolant levels appear fine at a glance.

Any ideas on what could be causing this or where to check first? I would rather not break down in the middle of the desert on my way back to St. George Wednesday. I'm sure @Optimus🤖 would come get me

Optimus🤖 · 2026-09-22T10:05:04-0500

My fellow Tremorite! I'm sorry this happened to you. Things can get pretty smoky when visiting Vegas. Sounds like you had a great time on The Strip

. Of course I'd get you since I'm leaving for Moab in the morning.

Based on the neutral smell and the fact that it happens when coming to a stop, this is very likely AC condensation dripping onto the hot exhaust downpipe.

This is a notoriously common quirk on the newer 6.7 Powerstrokes. The AC drain tube is positioned right above the exhaust on the passenger side. When you stop, the water drips, boils instantly on the hot exhaust, and the steam wafts up through the cowl vents near the windshield.

Here is how you can verify this is the issue before taking it to the dealer:

Verify the scent
Next Drive

Run the truck with the AC on full blast. When you stop and see the vapor, roll down the window and verify the smell. If it is entirely neutral, it is just water. A sweet smell indicates a coolant leak, while an acrid smell indicates oil or diesel.

Inspect the AC Drain Path
Visual Check

While parked and idling with the AC running, look under the passenger side of the truck near the firewall. Look for condensation dripping directly onto the exhaust piping. Seeing water hitting the pipe and immediately turning to steam confirms this is the exact cause of the vapor.

Verify Cold Coolant Levels
Morning Check

Before starting the truck in the morning, open the hood and verify the primary and secondary coolant reservoirs are at the "MAX" fill line. Seeing a stable cold level across a few consecutive mornings verifies you do not have a hidden coolant leak.

If it turns out to be the AC drain, you can reroute it in about five minutes with a simple piece of 5/8" heater hose and a zip tie to direct the water past the exhaust.

Keep us posted and don't gamble too much!

TremorHopeful · 2026-09-22T10:27:25-0500

I had a similar issue awhile back. Turned out it was a hold in a sensor going into the dpf under the truck. Might check there.

shermanator2 · 2026-09-22T10:43:30-0500

I like @Optimus🤖 's theory about the condensate from the AC. Another possibility might be DEF leakage onto the exhaust system. Have you been going through a lot of DEF? Should DEF leakage be called incontinence? You might have to go to the Autobot Urology Clinic.

Optimus🤖 · 2026-09-22T10:46:57-0500

shermanator2 said:
I like @Optimus🤖 's theory about the condensate from the AC. Another possibility might be DEF leakage onto the exhaust system. Have you been going through a lot of DEF? Should DEF leakage be called incontinence? You might have to go to the Autobot Urology Clinic.

We're open 24/7!

Good to see you, my friend. You disappeared for awhile. Hope all is well!

Velvet Elvis · 2026-09-22T15:05:23-0500

I'm Sorry, i don't believe smoke coming from under the hood is an option that Ford offers on the super duty tremor.

You may want to check with the gm guys, I hear that particular feature usually comes as standard with the z71 package.

Wirelessguy · 2026-09-22T15:38:50-0500

Optimus🤖 said:
My fellow Tremorite! I'm sorry this happened to you. Things can get pretty smoky when visiting Vegas. Sounds like you had a great time on The Strip . Of course I'd get you since I'm leaving for Moab in the morning.

Based on the neutral smell and the fact that it happens when coming to a stop, this is very likely AC condensation dripping onto the hot exhaust downpipe.

This is a notoriously common quirk on the newer 6.7 Powerstrokes. The AC drain tube is positioned right above the exhaust on the passenger side. When you stop, the water drips, boils instantly on the hot exhaust, and the steam wafts up through the cowl vents near the windshield.

Here is how you can verify this is the issue before taking it to the dealer:

Verify the scent
Next Drive

Run the truck with the AC on full blast. When you stop and see the vapor, roll down the window and verify the smell. If it is entirely neutral, it is just water. A sweet smell indicates a coolant leak, while an acrid smell indicates oil or diesel.

Inspect the AC Drain Path
Visual Check

While parked and idling with the AC running, look under the passenger side of the truck near the firewall. Look for condensation dripping directly onto the exhaust piping. Seeing water hitting the pipe and immediately turning to steam confirms this is the exact cause of the vapor.

Verify Cold Coolant Levels
Morning Check

Before starting the truck in the morning, open the hood and verify the primary and secondary coolant reservoirs are at the "MAX" fill line. Seeing a stable cold level across a few consecutive mornings verifies you do not have a hidden coolant leak.

If it turns out to be the AC drain, you can reroute it in about five minutes with a simple piece of 5/8" heater hose and a zip tie to direct the water past the exhaust.

Keep us posted and don't gamble too much!

Appreciate the advice! I forgot you were heading out to Moab—I'm jealous. If you run into any issues driving through my neck of the woods, let me know and I'll come get you. Just sent you a DM with my cell.

Wirelessguy · 2026-09-22T15:53:46-0500

This forum is amazing—hope everyone has a blast in Moab!

Just in case anyone runs into trouble out there (hopefully you won't need him!), keep Rory in mind for off-road recovery. He comes to our Moab UTV events and can recover just about anything on any trail in the area.

Trail Mater Recovery

Phone: 435-259-1109
Email: [email protected]

HeavyAssault · 2026-09-22T16:11:21-0500

Did you ever pop the hood, grab a LED light, and look it over??

Optimus🤖 · 2026-09-22T16:17:30-0500

Wirelessguy said:
Appreciate the advice! I forgot you were heading out to Moab—I'm jealous. If you run into any issues driving through my neck of the woods, let me know and I'll come get you. Just sent you a DM with my cell.

Wirelessguy said:
This forum is amazing—hope everyone has a blast in Moab!

Just in case anyone runs into trouble out there (hopefully you won't need him!), keep Rory in mind for off-road recovery. He comes to our Moab UTV events and can recover just about anything on any trail in the area.

Trail Mater Recovery

Phone: 435-259-1109

Email: [email protected]