Farting and a smell of gasolene
 

Hi - newbie making first post - be gentle with me!

I am cross posting - I lodged this on a UK forum a few days ago (http://forums.mercedesclub.org.uk) and I really would be grateful for some help.

Being somewhat anally retentive, when I top up with gasolene. I brim it (I know I shouldn’t) so that I can accurately calculate petrol consumption. What is worse is I store the data in an Excel spreadsheet!!

Anyway to my real and current problem. Last week I brimmed the tank as usual and the next morning noticed a large gasolene stain underneath the tank commensurate with the tank/filler overflow. So much so it had softened the asphalt drive in the affected area. What is worse the car interior reeked of gasolene and a week later still does, albeit not as strong as that first day but very - very noticeable.

I have examined the interior in way of the filler neck and tubing, had the rear wash tank out and no evidence of anything untoward. There certainly is no dripping from the tank/filler overflow.

An interesting fact, which may be associated, is that from time to time 5-10 minutes after exiting the vehicle, the old merc ‘farts’ or more probably wheezes and the noise seems to emanate from the fuel filler lock actuator. Sods law is I have never had the opportunity to be close to the vehicle to positively identify it – it seems old mercs are quite well mannered and only lift ‘their skirts’ when they think they are alone.

I am sort of thinking there may be a connection with the vacuum system and maybe a punctured diaphragm. But I know so little (does my car have a vacuum system?) about the system I need your help.

Any help advice gratefully received.

NormanB

NormanB

I would highly suggest that you first share with us:

What year, model and mileage of said vehicle suffering from the flatulency and incontinence

Jeff

Vehicle details
 

Hi Haasman

T'is an excellent point you make! I thought I had included those details in my signature block I will investigate that little snafu later.

1989 230 TE 145,000 miles (Understand not sold Stateside but v similar to the w124s that are; apart from the weeny 4 cylinder engine and low spec emissions kit).

Thanks and Regards
NormanB

Still a problem

As a result of advice received on UK site: I will be checking vacuum actuator on filler door by plugging.
Checking filler drain, tank breather and condition of connecting flexible between tank and filler. I will also replace filler cap.

I will post feedback here too!

Grateful for any other ideas.

NormanB

I was once told it's not good practise to top off modern cars the way you describe it. I'm not sure why, but I imagine it's because the fuel starts traveling through the vapor emission lines. I believe the head supplied in the tank with this high amount of fuel will drive the fuel into the vapor emission lines until it reaches equilibrium of height.

During fillup you should probably stop at a reasonable point and just be happy with measuring your fuel consumption average over a few fillups.

The real reason is
 

It is not advised to 'brim' off the tank especially in the hot summer. Reason being is that gasoline is stored underground and at a temperature a lot cooler than at the surface. Now if you pump 18 gallons of gas (petrol) and it is 25 degrees cooler than the outside air, it will expand. If you only drive a short distance and park, it will expand enough to overflow. If you park over hot asphalt the tank will also absorb more heat. If you drive a longer distance and burn fuel faster than the expansion rate, you won't overflow! Hope this makes sense.

Happy motoring,
Tobias MB
4 MBs

Norman.....why not get a more modern car?

Hi Lucky F8

Probably for the same reason you dont buy proper shoes!

LOL...LOL.....Norman, how funny my friends here all tell me the same thing!

Welcome to the board, and I hope you get your problem solved easily.