exhaust smell in cabin with windows or sun roof open

[Dono]

I'm looking for things to try here.
My exhaust isn't exactly stock, but exits the stock location.

What I can tell you is that I don't have an exhaust leak. With a window down, or the roof open its almost like the smell comes from the back of the cabin. It's surprisingly bad. My exhaust does really stink, there's no question about it, but It is bad enough in the cabin I think I need to figure out things to try.

With the windows up, and the heater fan on there is no exhaust smell.

Is there any air vents at the rear pulling exhaust gasses in? Any factory holes at the back I should be sealing? I think my tail gate seals well against the body. Seal the inside skin of the tailgate with something? Any factory holes towards the rear I can seal?

I thought about getting a 3" 45 degree piece of exhaust pipe and trying to re-direct exhaust more to the passenger side of the truck just to see if there is a difference.

Iv'e had this issue for years, and now the truck is running better and better so I'm focusing on other irritating issues. I'm kinda grasping at straws here.

 

[Turdle]

I suggest looking more closely at the rear hatch and window seal. There is a huge amount of negative air pressure at the rear while moving and from previous smoking experience I know rolling down a window creates a vacuum which will cause smoke to go out the window.

So, now try think of your truck as a huge bong, when you open the window you are letting off the carb hole and pulling all the fumes to you.

That's my theory and I am sticking to it.

 

[vroomzoomboom]

a huge bong! hoola crap jon, thats funny!!!!
don, your tip comes out the back right? the question may also be is it out far enough?

 

[Turdle]

crap, I just thought of the dummy vent panel in the rear hatch, it's there but hidden by the plastic interior panel. It's thru the inner sheetmetal. The latch handle and latches are the holes out the other side.

 

[gmanpaint]

I have heard this from those, that run straight out the back.

I have not heard this from those, that run out the sides behind the tire.

My theory on this, as I have gone through this myself in the past.

Your "Wake" in the air stream as you move, gets mixed with the exhaust exiting out the rear on a flat backed SUV. It can actually flow back and get sucked in by the interior vac as Jon brought up.



Change the exit to the side, and this won't happen anymore. I'm not sure if a rear spoiler would help here, by changing the Wake pattern. Might make it worse. LOL

 

[Dono]

I think you guys are dead on. I need to try both.
When driving on a gravel road, or in the rain you can clearly see all the road stuff getting pulled up on to the glass.
This explains the exhaust being pulled up to the rear hatch.
Attempted fix: Change the exhaust more to the side, and extend it out a bit further. How it looks does factor in to this though, I don't want some long arsed pipe sticking out.

Rear hatch:
I need to take the hatch panel off and make sure the plastic is sealed really well. A big tube of acoustiseal, Some thick vapor barrier, and some construction tuck tape should ensure a good seal. Maybe even do something like this:

Then, look closely at the actual hatch and hatch window seals. I know they are in great shape, but maybe not sealing real well. I'm sure if I close the door/hatch on a piece of paper and run it around the seal I should be able to feel if the seal is not contacting in a spot.

Or, just embrace a bong and it wont matter to me so much. lol.

 

[Turdle]

Shhhh, it's a vase

 

[CDW6212R]

crap, I just thought of the dummy vent panel in the rear hatch, it's there but hidden by the plastic interior panel. It's thru the inner sheetmetal. The latch handle and latches are the holes out the other side.

The air gaps in the hatch itself is probably most of it. The seals of the doors and hatch work well unless the doors or hatch get unbolted and installed in a different spot. Then the old seals don't fit the gaps so well anymore.

I'd pull the hatch trim and spend time as you planned, trying hard to block the air gaps leading to the inside.

Has the truck had anything bolted into the quarter panel floors? Anything like that usually leaves some small screw holes behind, under rugs etc. I've filler a lot of those in my used Fords, from prior owner's stuff. Ultra Black RTV fills those holes well.

Be sure the hatch and doors do fit the body well, and the strikers are all good.

 

[Dono]

I'll proceed as planned. There has been nothing non-factory bolted to the floor. I don't like to drill holes or shoot screws thru the floor. It does raise another good point that I might want to pull the side panels off in the cargo area and pull the carpet back for a look also. There might be some factory sealing starting to go bad, or maybe even double sealing where there are any body plugs.
I may even just try moving the hatch striker in a hair so that the hatch pulls to the body a bit tighter (As long as I don't start rubbing paint on paint).

There's no rust to deal with, so at least that's not the issue.

 

[gmanpaint]

Well heck, if your pulling the carpet, might as well spend $75 on 80 mil killmat and cover the floor.

That will not only seal the floor, it will provide some sound dampening from exhaust, and road noise. Added bonus, it helps with HVAC temps.

 

[toypaseo]

Maybe shoot your exhaust out the side, like my Gibson catback

 

[toypaseo]

or get a deflector that will force air down...

 

[Dono]

or both!
I can't go out the side like the Gibson unless I take off the resonator/muffler I just installed back there. I think I can get a 45 degree angle at the bumper though.

I don't think finding a deflector will be easy anymore. Also, probably pricey. I do think the deflector would go a long way to resolving my issue though.
edit: I stand corrected.
Aerowing Rear Window Deflector - Smoked; 1998-2000 Ford Explorer/01-03 Explorer Sport/99-01 Mercury Mountainteer

 

[toypaseo]

Stacks

 

[4pointslow]

This thread is awesome, and funny!
I too have Exhaust coming back into my truck sometimes, tail pipes face straight out the back in the middle.
Let me know what works for you Dono.

 

[CDW6212R]

If you turn the exhaust tips down a bit, that will point the flow away some more.

 

[donalds]

lol

 

[Hacra]

I have my exhaust pipes pointing downwards just before rear axle, no smelly business.

Perhaps spoiler to divert the air flow?

 

[Dono]

I'm surprised you don't get a smell with dumping your exhaust under your truck like that. Interesting.
The time I was hoping to spend sealing my tailgate and looking for issues in that area just got swallowed up by me now needing to replace my header gasket. I was hard on the gas this morning, and blew out a section of the gasket. ****.

 

[Hacra]

Looking at the animations of the air flow, it would seem that, if the exhaust pipe tip is at the very back of the car (as it usually is), the exhaust fumes tend to get caught (gets pulled upwards) in the vortex that forms, so in my case the exhaust fumes gets mixed to the rushing air earlier, plus my exhaust tips point at 45° angle towards ground, surprisingly enough i don't get exhaust fumes inside even if i am not moving, not in the quantities that would bother me anyway...

Easiest way to visualize this is in the winter time, if you look at vans and see how the vortex of air glues the snow to the back door/side/whatever it is called, where as in normal passenger cars it's not as likely and/or common, now the back end of explorer reminds more of van than normal passenger car.

I hope you can understand what i am trying to say, as i am not native english speaker, my vocabulary escapes me. /end of rant.