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Exhaust smell in cabin

Paul K

Paul K

Well Known Member
I've done a search and see that lots of us seem to get exhaust smell in the cockpit when we throttle back to slow down but I don't see any solutions or fixes. It doesn't bother me so much but it really bothers those who ride with me.

RV 7A With the following:

Slider, tight but not sealed
Vetterman 4 pipe system, can't see any leakage
Boots on aileron push rods
Firewall sealed
Doesn't seem to be entering through the side vents or cabin heat
Happens with or without the vents open
Always happens when I power back to slow down

Any experience and solutions?
 
Perhaps when you throttle back, the exhaust fumes flow a little closer to the fuselage bottom and enter the back fuse near the tail, working their way forward and eventually past the rear baggage bulkhead (with those large triangular holes at the corregations). You may want to seal the baggage bulkhead and see if it makes a difference.

Bevan
 
I wouldn't seal the baggage bulkhead. That how air "leaves" the cabin. If that is sealed opening the vents will somewhat pressurize the cabin and will cause a whistle around the canopy.
 
Thanks for all the suggestions! A little different than what I was thinking but if sealing the canopy and the baggage bulkhead is the answer, I'll give it a try.

A further note, when I cut back power to descend, the exhaust smell is instant.

I also have a Co detector and it hasn't activated yet. I'll do a test to make sure it is functioning.

I have felt glued to the rear skirt and that part is really tight. The sides not so tight! I'll start the experimenting.
 
Exhaust smell

I too, smell exhaust when descending at reduced power. It's not over-bearing, but enough to get my attention. As a base line, I never smell exhaust in normal flight.

Jim Diehl 7A
90 hrs total time on engine/airframe
 
Jim,

Same here, never in normal flight.

Question is, what is different about 140n low power descent aerodynamics versus 140n normal cruise? Or another way to state it, high speed level flight while powering down versus high speed level flight normal power?
 
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Timely post.

I had the same issue when using cabin heat. Took the bottom cowl off today for mixture adjustment. I did a look around as I do when ever she's undone. My exhaust hanger has slid down the engine mount. The new position has worn a hole through my high temp scat tube exiting the heating shroud.

Fixed it today. Hopefully fly tomorrow to see if that cured the issue. (Thinking that positive pressure would keep out the in-flow of exhaust I'm still wondering if that'll fix it)

Regards,

Scott
 
Heat muff location

I originally had a similar issue. Turns out I did a dumb thing. I had the heat muff in a very convenient location, spanning an exhaust joint! As you pull back the throttle, one pipe cools faster than the joint and a gap opened ever so slightly - out came some exhaust...into the cabin. After a few minutes the smell would go away after the transient thermals caught up. Drove me nuts for a few months.

I thought it might have been a crack in the pipe, but it all made sense after I realized it was just a dumb oversight.

AO
 
Exhaust odor...

Somewhat timely thread --- My right wing root seal came loose the other day and I started to smell exhaust during the descent (@ low power). I have an angle valve IO-360-A1 w/ standard Veterman 4-2 crossover exhaust, and a fairly tight tip-up canopy.

Interesting how airflow behaves...ain't it.

b
 
Exhaust in the cockpit when powering back

It would be interesting to know, of all the 7's out there with sliders, who has this problem and who doesn't? What do the problem free RV's have different from those with the exhaust in the cockpit problem?

Before I go changing anything, sure would like to conduct some kind of survey to narrow down the causes and fixes. Anyone know how to go about such a task?
 
Its not clear to me that all the posters are sliders.
Even if they are all sliders, maybe this will help.

I have a tip up with known gaps so it is not sealed, aileron boots, tight fitting wing root fairings, and sealed baggage bulkhead. M1B with Vetterman 4 into 2, no mufflers.
I have never smelled exhaust fumes in any flight regime.
 
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For the record.
Mine is a slider,
has aileron boots,
tight fitting wing root fairings,
baggage bulkhead has interior cover,
Vetterman 4 into 2,
no mufflers.
a Co dectector .

Slider has small gaps along both sides that I have jammed material in to see if this will stop the smell. No Joy
 
rzbill said:
I have a tip up with known gaps so it is not sealed, aileron boots, tight fitting wing root fairings, and sealed baggage bulkhead... Vetterman 4 into 2, no mufflers.
I have never smelled exhaust fumes in any flight regime.
Click to expand...

Me too on all points.
 
Hmmm... Does anyone with sealed baggage bulkhead have exhaust smell at any time during a flight? Not nearly enough evidence in yet but could this alone be the answer?
 
My 6A has the baggage bulkhead "sealed" with little triangles of foam. Aileron boots, etc. Still smell some exhaust when slowing down. Never enough to trip a CO2 detector. Even with cabin vents on full, I still smell it. Flaps up, flaps down, doesn't matter. Pipes cut at a slight angle pointing down, and they hang about 3/4" below bottom of scoop. I've got some exhaust downturns from Larry that I need to try (I've had them about a year...). I've also got two 1/4" holes drilled at the low point of the fuselage (when on the gear), probably worth taping those up sometime also. Those would actually be in line for picking up some exhaust if the flow is inward.
 
We get it all all the time on final - it's coming in through the flap drive holes.

Don't worry - it's a Van's :D
 
Mike,

If that is so, any thought about boots for the aileron pushrods?

Im looking for any and all suggestions because my wife will not fly with me until this is resolved!
 
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