The last few times I've stepped out of the car and I've heard a gurgling sound from the back end of the car. I've looked around the car and nothings obvious or out of place. The only thing I can find is the drain hole underneath the petrol filler cap is blocked. This pulled out easily enough but only so far and tried to clear it, so before I stick an airline down it. A...is this bloked tube likely to cause the noise, and B...will blasting it with an airline be ok? Does anybody know where the other end comes out. Cheers.