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#4449559 - 07/04/17 04:12 PM Gasoline smell without catalysts
Building3 Offline

Registered: 04/30/17
Posts: 82
Loc: Michigan
I am old enough to remember cars without catalysts and they did not smell with the gasoline of the day. Now, when I run my older non-catalyst cars (vintages 1966 to 1972) they smell from the gasoline. There are no exhaust leaks and the carburetors don't leak. Even tweaking the mixture to run a bit lean is no help. So can anyone tell me why the smell is only on cars without catalysts? Did the government make the refiners add something to the gasoline so that non-catalyst cars would smell? I used to use "normal" 93 octane fuel that I use in my daily drivers, then I switched over to ethanol-free gasoline hoping that the smell would go away. It did not. Is there any additive available that would diminish the odor? Thanks

#4449561 - 07/04/17 04:14 PM Re: Gasoline smell without catalysts [Re: Building3]
901Memphis Offline

Registered: 08/14/10
Posts: 12893
Loc: Northern Kentucky
I'd be surprised if anything would change the smell.
2012 Chevy Cruze LT 1.4T - 50k
2002 Buick Century 130k - Built 4T65e(Maxlife) - Edge 0w40 + Fram XG3980

#4449569 - 07/04/17 04:22 PM Re: Gasoline smell without catalysts [Re: 901Memphis]
440Magnum Offline

Registered: 02/01/09
Posts: 8754
Loc: Texas
Originally Posted By: 901Memphis
I'd be surprised if anything would change the smell.

Oh, you'd be surprised. Leaded fuel has a very distinctive sweet smell. Go to an airport and hang around the general aviation area as the little Cessnas and Pipers fire up on 100LL fuel, or better yet an airshow when the big radials and Merlins crank up. I would say go to the dragstrip and smell the cars that still run leaded race fuel, but they actually make *perfumed* race fuels these days! You might not be smelling plain leaded race fuel anymore.

And exhaust from leaded fuel back in the day DID smell, we were just used to it. I remember how strange unleaded fuel smelled the first time I used it (without catalysts- 70s catalysts smelled like rotten eggs most of the time, as do a lot of Toyotas at full throttle still today). But then years later I came across some leaded fuel and ran it, and then noticed *IT* had a very strong smell after I'd gotten used to the unleaded smell. A lot of it is about adaptation and perception. Nothing is added to ordinary street car fuel to make it smell different in non-catalyst cars. Catalysts just actually work now, and really reduce the odor from partially-burned hydrocarbons down to nothing. Also, vapor control systems work and so you don't smell the raw fuel when you pull a new car into the garage the way you do when you park an older car without an evaporative emission control system.

Edited by 440Magnum (07/04/17 04:24 PM)
'66 Dodge Polara & '69 Dodge Coronet R/T both 440/727
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#4449582 - 07/04/17 04:32 PM Re: Gasoline smell without catalysts [Re: Building3]
JTK Offline

Registered: 08/14/03
Posts: 10559
Loc: Buffalo, NY
I don't know if it was the fact there were not quite so many vehicles on the road back then, or we were just used to (or numb to) the exhaust odor. It was there then as well. I hear you though. I know I can smell a classic or muscle car way ahead of me these days. Or a flock of motorcycles? Ugh.. One little trip in one is probably the equivalent of a month's worth of driving in a 2017 vehicle in terms of pollutants.
2017 Ram 1500 4x4, 3.6L. 2016 Nissan Quest SV (Babe magnet IV)

#4449602 - 07/04/17 04:59 PM Re: Gasoline smell without catalysts [Re: Building3]
Ethan1 Offline

Registered: 12/29/14
Posts: 1632
Loc: 'murica
Yeah I think everybody was just used to it back then. Nowadays cars run clean. If you hop on the freeway behind a classic car, a TBI-equipped Chevy, or an all-around jalopy, you know to reach for the recirc button.

#4449641 - 07/04/17 05:27 PM Re: Gasoline smell without catalysts [Re: Building3]
Nyogtha Offline

Registered: 10/13/14
Posts: 2319
Loc: San Antonio, TX
The main thing replacing the octane boost tetraetyl lead used to do is aromatic compounds from catalytic naphtha reforming. This is the main, and in some cases only, real octane "adjustment knob" in refineries. Some say these compounds smell sweet, I beg to differ. Aromatics are middle to high boiling in the gasoline mix so they don't vaporize as easily when an engine is cold started. In carburated engines this would lay down in the intake manifold at first then vaporize as the engine warmed up. With fuel injection this is rammed straight through the system and can be quite rich in the exhaust until the catalytic converters reach activation temperatures. So there's a number of factors at work. Ethanol has added its own note to exhaust fume bouquet, as did MTBE when it was in use.

As a teenager most of the family fleet ran on regular leaded but Mom's car, the newest, a 1978 Buick Skylark, took unleaded, and I well remember the difference in exhaust smell with Mom's car. I preferred the bouquet of regular leaded exhaust as well.
"No matter how paranoid you are you're not paranoid enough. Tell the truth. Reach as many people as you can with it. That's your weapon." - Susanne Modeski, aka "Holly" to The Lone Gunmen

#4449685 - 07/04/17 05:57 PM Re: Gasoline smell without catalysts [Re: Building3]
NHGUY Offline

Registered: 10/09/11
Posts: 5040
Loc: USA
Summit or Jegs used to sell flavored gasoline additive.Blueberry was my favorite.

#4449857 - 07/04/17 08:56 PM Re: Gasoline smell without catalysts [Re: 440Magnum]
Ducked Offline

Registered: 10/25/12
Posts: 4320
Loc: Taiwan
Originally Posted By: 440Magnum
70s catalysts smelled like rotten eggs most of the time, as do a lot of Toyotas at full throttle still today).

Yeh, remember that. At the time I thought it might be the "new car smell" that everyone raved about. Couldn't see the attraction.

I suppose but for that early misunderstanding I might have become a happy, well adjusted consumer.

Too late now.