white residue on gas cap and gas insert (corrosion?) - The Unofficial BMW M5 Messageboard (m5board.com)

DIPLOMAT · 10th December 2004, 12:58

Hello,

so I filled up the beast for the first time last night

, (yes I just got her a week or so ago), and I noticed that there is some white residue on the gas cap and also around the rim of the fuel thinggi where the nozzle gets inserted. There is also a little bit of this residue on the flap inside the fuel hole. It looks like it is some white and kinda hard stuff but I can pretty easily get rid of it with some scrathing. It atually looks like limestone, I think it is called in english.
any one of you have that or have any idea what this can be? Bad gas?

thank you
J

TCM · 10th December 2004, 17:07

Maybe residue from the polish or wax used when the last person detailed the car? Residue tends to get in around the gas cap area and leaves a chalky white buildup. Hopefully, that is all this is. Best of luck and please keep us updated.

DIPLOMAT · 10th December 2004, 17:38

Quote:

Originally Posted by TCM

Maybe residue from the polish or wax used when the last person detailed the car? Residue tends to get in around the gas cap area and leaves a chalky white buildup. Hopefully, that is all this is. Best of luck and please keep us updated.

I knwo that the car was detailed regurlarly, but I know that it is not wax buildup, I knwo what that look slike. and also there would not be any wax down inside the fuel hole that goes to the tank on the little flap. gosh it si sso difficult to explain

Philip · 10th December 2004, 21:34

I have no such substance in my fuel fill area, nor have I heard of anyone with this problem. If it's not wax buildup and it's under the fill cap, then perhaps a more serious problem. Any problems with the engine's performance? Maybe you should take a sample of it to keep for future analysis?

canysmc · 10th December 2004, 21:39

Oxidation of the surrounding metal?

BmwNut · 10th December 2004, 22:39

Just a WAG, but hard water residue? Maybe the previous owner didnt try out the fuel filler area after washing it, which if you live in an area with hard water would leave a hard white ring around the area. Dont know how it would get into the filler neck though...

DIPLOMAT · 15th December 2004, 10:39

Quote:

Originally Posted by canysmc

Oxidation of the surrounding metal?

can you explain further please, I know for a fact that it has nothing to do with washing the car.