I have a 2005 C230 K that is great. Have no problems other than wearing out back tires frequently (my fault). There is something interesting though. It has happened from brand new. The mechanics that I use think I'm crazy but every time I drive my car in the rain I get the same result. After driving in the rain for the day or whatever amount of time I park it over night. When I get in it the next morning, there is a very prominent gas odor of some sort. After I drive it again it goes away until the next time it rains. The car itself never shows any kind of problem, it just has a weird smell. Does anybody have this same occurrance? What in the world is it?

 

That's a good one! I'm trying to link rain or water to a gas smell from that, and I just can't come up with anything for you.
The only thing I can think of is that it's not really "gasoline" that you're smelling after the rain. I'm not saying you don't know
what gas smells like, it's just that there is almost (I said ALMOST) no way rain could make a gas smell. How would water
possibly access the fuel? There's the tank, the filter, a steel line, and the injectors. All not exposed to water. Beats me!
Now, if you had a fuel LEAK somewhere, that would be different. But that would be fairly obvious and you'd smell it all the time
I'm guessing. My guess again is that it may not be fuel you're smelling after the rain. Be sure not to "top off" your gas tank too.
Just let the nozzle click itself when you fill, and remove it. Overfilling or topping off is a no-no. Sorry, I'm lost on this one.
And that's probably why your dealer/mechanic has no clue....it just doesn't make sense.

 

Could this be related to barometric pressure? and perhaps a weak seal on your gas cap? i know the barometer falls when storms come in...less pressure in the outside air...meaning the pressure on the inside of your gas tank can perhaps overwhelm the vapor seal of your gas cap. like having less resistance from the outside air pressure pushing 'in' on it. just a thought.

 

I wonder if what you are smelling is mildew! Is there any leak in the trunk that dampens the material lining the sides or floor? I had an issue in a 1998 C230 where water was leaking by the left rear lamp cluster, under the trunk floor liner and filling up a small metal pocket. It did not fill it up completely unless there was days of rain - which is how I located the problem. However, it caused a smell of dampness, stinkiness, a pong which was not so dissimilar to gasoline. It would fade away after a while and then return the next time it rained.

Just a thought!

Lawrence

 

Date: June 28, 2007 Order No.: P-B-94.20/05c Supersedes: P-B-94.20/05b dated August 15, 2006

Found this:

Odor in the Interior If you receive customer reports in the above model vehicles regarding an odor in the interior is either a strong oily (putty) or acidic (vinegar) or butyric acid (rancid butter) smell and other potential sources have been ruled out, the source of the odor may be the soundproofing mat on the interior side of the transmission tunnel. This odor will be present even with the engine and HVAC turned off and becomes more intense after the vehicle is parked for an extended period of time with the windows and sliding roof closed. 1. Pull back the carpeting on the side of the transmission tunnel. 2. Smell the exposed tunnel soundproofing mat, if there is an odor similar to the customer complaint, proceed to step 3. 3. Flex the exposed tunnel soundproofing mat, if the mat breaks when bent back and forth proceed to step 4. 4. If there is a strong odor and/or the mat breaks after a few bending movements, the tunnel soundproofing mat material must be replaced. It is necessary to remove the AC housing. Refer to the following applicable WIS documents: Model 203 AR83.30-P-5200P

 

this is a weird problem

 

So far the gas cap scenario has me intrigued. As far as leaks go, there are none. Bought brand new and never wrecked. Garage kept, 35,000 miles, no door or trunk trim problems. Will look into the gas cap area futher.

 

Also, the odor is only after driving in the rain. If the car has been sitting and I get in while it is raining it is not there. It may not be gas but it smells like fumes of some sort.

 

I just had a thought. It's probably a long shot, but.......since you say it may NOT be gas fumes but something like that, you might
try this: Do you know where the cabin filter is? Have you replaced it yet? The one under the hood I mean. It's UNDER the black plastic
"tray" over your battery. It's held on by three metal clips. Flip it over and look at the filter there. Is it white? Or is it mildewed?
This thing filter the air coming in your car/blower area. Just a thought. Take a look anyway. It only takes about a minute to pop it off.

 

You know, I have thought of that before. I have had it replaced twice so far. It seems to get dirty fast whereas the air filter does not. Both times I replaced it the mechanic said it was really dirty. I will check into that department again.