Water Ingress by Filler cap

[Friday]

I've got a water ingress issue by my petrol cap. After days with the hose I've found where the rain is coming in - by the seal of the filler cap (highlighted in red). I've siliconed it as a quick fix but I was surprised that water was finding its way into the boot and gathering by the wheel arch under the rear light. Anybody had anything similar? Is the fix buying a new cap with a fresh seal or something else?

 

[Pedro]

There are drain holes around the filler pipe flange that need to be cleaned same on the boot valance if any of these get blocked then you will have water inside

 

[Friday]

Thanks for your reply.
The drain holes around the filler pipe work fine. It’s the rubber seal at the bottom of the filler surround: where the rubber seal meets the painted body work. I can slowly pour water on that seal and I can see the water disappearing into the body - and it reappears inside the boot by the wheel arch (under the rear light cluster.)
It’s an odd design there as the rain pools on that seal as it’s a local minimum - a small well.

 

[Friday]

Here's picture of what DOESN'T happen to mine. If you look at the bottom you can see the pooling of water - on mine the water just seeps under the seal.

Is there any adjustment in that seal - can you tighten anything up? Looking at the schematics there doesn't seem to be anything that will force that seal tighter. Or, does that require a new fuel cap/sealant?

 

[Friday]

An update in case this helps anyone:
Original symptom was a wet drivers footwell. After days with the hose it came down to water ingress by the filler cap. Water came in and pooled behind the wheel arch (take the boot trim off and there it is - under the rear lights)
Water pools by the wheel arch then trickles under the back of the rear bench seat. It comes out by a hole in the bodywork, under the back seat by the door sill and into the drivers footwell (under the carpet)
Solution has been a bead of silicone at the bottom of the filler cap unit - might replace at some point. Simple way to see if it’s leaking is to see whether the rain pools by the closed cap. If it doesn’t then the seal is letting the rain into the bodywork. It’s a bad design that rain doesn’t run off but pools in a small well at the bottom of the cap unit. Just to be clear, I’m referring to the seal to the painted bodywork you can see when the fuel flap is closed - nothing to do with drainage holes inside the unit.