I know everyone raves about inbuilt swimming pools but having one in my car is just not for me.
A number of years back I started to notice that it was taking longer and longer to clear my windows (on the inside) during the winter months and that it wasn’t just the “normal fog” you get but full blown condensation that had to be wiped away. Well, it turns out that Ford decided to give everyone who owns a MK3 Ford Focus the non-optional extra of having a swimming pool build up in the spare wheel well whenever it rains, I know right?! How nice of them! After some digging online it seems that the rear vents behind the bumper that allow air to escape the cabin also allow water in. Water would build up in the cavity behind them and then overflow into the rear of the car and if you were really unlucky it would overflow from the boot and down under the rear seats and under the floor. Luckily for me mine never got quite that far!
If you crawl up under the rear of the car, there are two bungs (one on each side), pull those out and they basically act like drain plugs. The first couple of times I did mine water poured everywhere, I eventually found that until I could permanently solve the issue I was best just leaving them undone (or I would duck tape over them if I was expecting to drive a lot in the rain) allowing the water that flowed in to flow right back out again.
After the latest round of winter I decided it was finally time to whip the rear bumper off and seal these vents once and for all (or at least I hope so). Getting the bumper off was rather easy, the biggest issue was the wiring harness for the rear parking sensors as it was brittle/stuck solid! Once the bumper was off it was just a case of removing the 4 vents (not the easiest of tasks but taking the smaller rear ones off first will allow you to get your hand in and release the larger ones from the inside). Cleaned up any left over water inside, filled it with some cavity wax and then applied some water proof silicone all around the vents essentially glueing them back on. Let’s hope it holds!
The problem seemed to be the poor seal these vents have with the bodywork of the car, they move/rattle around. It looks like the plastic/rubber seal may have once held tight against the car but overtime, as it dries out, less so. With this poor seal, the water that runs around the boot, behind the rear lights and down over these vents ends up just running inside.
Moral of the story? If you own a MK3 Ford Focus and you find the inside of the car is oddly damp during the rainy season, take a look in your spare wheel well and see if you have any water build up.