Gas Smell in Cab

[surfbus23]

I recently started noticing gas smells while driving. The smell has gradually been increasing. It gets pretty bad when I fill the tank and goes away when I don't have a lot of gas. Isolating the smell of the gas has always been difficult. For some reason it smelled more strongly in the drivers seat than elsewhere in the van. It also mostly only smells if I'm driving. I live full time in the van, so can verify that it doesn't leak when sitting.

Checked the main fuel lines and the air breather hose behind the spare tire wheel. Everything clean and tidy. Popped off the plate to check out the filler hose and all good there. I noticed under the bus a small wet spot coming from a bolt that looked like it could be coming from the gas tank area.

So my next thought was that I need to examine behind the fire wall. My hope at this point was a breather hose had popped off, but I'd replaced them 4 years ago with the Gates Barricade line and stainless steel hose clamps. Same with the filler hose rubber. New gasket for the sender, etc. Everything new and redone to avoid exactly this.

I sacrificed some pristine looking engine tin in the name of solving my problem. I'm in a small town in the Argentinian Andes, so dropping the engine a couple inches wasn't an option. Unfortunately, I observed no obvious easy fixes like a cracked hose. There was a nice undisturbed layer of dust around all the usual suspects: sender unit, filler tube, breather hoses, breather tubes.

What I did find was this:

Sorry it's not the greatest picture. I'm not really sure what to make of it. My best guess, given the line across the wall is that perhaps the seam is weak and when pressure builds up in the tank while driving it is spraying the side wall? That sounds a little far fetched, but literally none of the other points of leakage are leaking and the seam is all that I can think off.

This was pretty much a rust free gas tank when installed 4 years ago.

Any thoughts?

[dodger tom]

you don’t say what year, engine, etc.

you also don’t mention a charcoal canister. they and their hoses can be the source of gas fumes. as can the pressure relief valve in the air cleaner, depending on year, of course.
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1978 Champaign Edition 2 Westfalia
Would never find the time to keep up another classic air-cooled.

[surfbus23]

Opps. 1979 2.0L. I have the gas canister installed with the proper charcoal in the canister. 26k miles on the charcoal if that makes a difference.

[SGKent]

my GUESS is that if it is a late bay, the O-ring under the sender has failed, or a hose has come off. There is a pair of hoses on the top of the tank as well, maybe one has come off. Hard to say but you need to look at the top of the tank because the stain comes down from there.
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"Most people don't know what they're doing, and a lot of them are really good at it." - George Carlin

[surfbus23]

[surfbus23]

Another strange element of this is that I really smell the fumes best in the drivers seat. I can kind of but only kind of smell the fumes under the rear bench seat on the drivers side.

Right now I'm thinking I'll have to fill up again tomorrow and just try really really hard to pinpoint the smell.

[Wildthings]

Never heard of it happening on one of these rigs before, but maybe you have rubbed a hole in the tank? I have certainly seen this on tanks in other rigs. Just a rust hole would be another possibility.

[surfbus23]

I took a lot of videos with the flash on inspecting all around in there. The only thing I found was this area, which I do find suspicious. Like why is the moisture line exactly lined up with the seam. There's a small amount of moisture on that far corner and the near corner.

I guess I'm curious if anyone has ever heard of a seam going bad? I guess the seam is welded though.

What would make it worse when I drive? If I have the entire breather system functioning properly is it under pressure?

[Wildthings]

The metal near a seam can fatigue and crack with time.

[Abscate]

Get the engine and tank out and fix it. You are going to have more than one issue on a car 4x past it’s life expectancy, to be blunt

If you used cheese grater stainless clamps from a toy store, they aren’t stainless and they will be leaking by now, too.
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[Xevin]

Have you recently checked the rubber fuel elbow for splits or tears?
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Keep on Busin'

[mikedjames]

It is possible your tank has pinholes in it, or that the filler hose is leaking slightly where it joins the tank.


The mark may just be where fuel is running along the bottom of that panel : it looks like there is a lot dust which may be allowing the gas to soak into the dust from the leak, soak all along the tank and then at a certain height it evaporates away.

Do not forget the tank breather join just in front of the spare wheel well on the drivers side, this could be leaking and the fuel is running forward along the outside of the breather pipe, and into the tank area.

It does not take long for fuel hose to crack in that position, the heat from the engine plus the fuel inside the breather when you fill up the tank soon weakens the rubber fuel hose in that breather joint position.

On the passenger side that breather joint is further round the breather system, after the loop in the air vent, so it does not leak fuel if it breaks.
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Ancient vehicles and vessels

1974 VW T2 : Devon Eurovette camper with 1641 DP T1 engine, Progressive carb, full flow oil cooler, EDIS crank timed ignition.
Engine 1: 40k miles (rocker shaft clip fell off), Engine 2: 30k miles (rebuild, dropped valve). Engine 3: a JK Preservation Parts "new" engine, aluminium case: 26k miles: new top end.
Gearbox rebuild 2021 by Bears.

1979 Westerly GK24 24 foot racer/cruiser yacht Forethought of Gosport.
1973 wooden Pacer sailing dinghy

[ALLWAGONS]

After a year of dealing with light gas smell, I finally found the culprit.

While installing my stereo, I has access to the gas tank.

NO LEAKS! WTF?

Turned out to be my NOS Gas Cap. Even though the cork seal was good, The inner rubber seal had fallen apart. As the gas splashed around while driving, the smell would travel out the cap, into the air intake vents back to inside the bus.
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Thanks to my Tesla driving neighbors, I feel more relaxed driving my SUBURBAN and old VW's.

Everything sounds good on paper!

[SGKent]

glad you found it. No more where the heck is this coming from.
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"Most people don't know what they're doing, and a lot of them are really good at it." - George Carlin

[orwell84]

Glad you found it and thanks for sharing. I get the occasional whiff of gas in my bus in spite of everything being checked over. It used to be way worse but I thought it was normal. Since that time, I now have a boroscope camera for my phone. Will make checking the filler neck much easier. Happy trails!