Explorer - Water Tank Key

[JohanJvV]

I have lost the key to my Explorer's water tank.
Went to a Jurgens dealer, they gave me 5 keys they had and sadly none fits.
Since there is no numbers on these keys (Jurgens changed the system, the door key does not work on the water tank anymore) what am I to do

[Johan]

My Xplorer is a 2007 model and the water tank key(without any number) is also different from the door key, but they gave me duplicates for both keys, when we bought the caravan.
I think your best bet is to get the help of a locksmith.
Don't know what is the cheapest, the locksmith or a new cap.

[JohanJvV]

I also got a spare key for tank and Caravan, problem is those three keys are lost.

So I will most probably have to break the cap.

[Johan]

My caravan is parked to close to the garage wall(with no one to help me move it) to access the filler cap, to have a look at it's workings, but I think it's a outer and inner housing that got locked together when you unlock it. When it's locked the outer housing is turning free.
So I was thinking if you drill a small hole in the cap through to the inner section, and then screw in a self tapper, then you might be able to remove the cap, without destroying it.
Just a thought.