E39 fuel flap water collection.

[Tazar]

I’m sure many suffer this problem but every time it rains or I wash the car water collects underneath the fuel cap and I have to dry it with a cloth. I believe it’s supposed to drain away but it doesn’t. Any suggestions?

[d_a_n1979]

Nope; the E39s (for some daft reason); never had the drain fitted.

So as you said; it sits and gathers and a well known rust spot...

Clean it throughly; dry it thoroughly and then ceramic coat it and that should keep any issues at bay. You'd have to maintain this

You could use a clear underseal maybe or something like Lanoguard; but you'd need to keep on top of it also

[Pica-Pica]

Tazar said:

I’m sure many suffer this problem but every time it rains or I wash the car water collects underneath the fuel cap and I have to dry it with a cloth. I believe it’s supposed to drain away but it doesn’t. Any suggestions?

Do you mean fuel filler cap, or fuel filler flap?

[Tazar]

It’s frustrating but something to live with. I knew about the problem before I bought the car and it was one of the things I checked out. As soon as I arrived home I applied some Bilt Hammer under seal and that’s kept it but I just wondered if anyone had some tips other than regular drying.
Has anyone drilled to make a DIY drain away?

[d_a_n1979]

Tazar said:

It’s frustrating but something to live with. I knew about the problem before I bought the car and it was one of the things I checked out. As soon as I arrived home I applied some Bilt Hammer under seal and that’s kept it but I just wondered if anyone had some tips other than regular drying.
Has anyone drilled to make a DIY drain away?

Folk have tried by lifting the metal where the seam is; but not advisable as it'll just cause more issues

Leave it be and keep on top of it being dried and treated - that's the best way

[Tazar]

Okay, will do.

[RichardM5]

Tazar said:

It’s frustrating but something to live with. I knew about the problem before I bought the car and it was one of the things I checked out. As soon as I arrived home I applied some Bilt Hammer under seal and that’s kept it but I just wondered if anyone had some tips other than regular drying.
Has anyone drilled to make a DIY drain away?

If you drill a hole the water will just drain in between the inner and outer wing, which will make it rust like hell internally as there is very little protection in there. I've seen people literally fill it so it's level with silicone, but I just make sure it's well protected and as dry as possible.