we have a Ranger too our 2nd one actually,we never had it with the 1st one but did with this one on the last trip in severe rain. I have asked a caravan engineer about this he said that vans with the larger front window can sometimes suffer this, as the window can flex a bit in travel. I have inspected ours since and no problems at all, I checked it yesterday after a downfall and all is good.
If you open the window fully and give the inside a good clean with soapy water then dry off, and apply some silicone rubber lube round the seal it should help, the lube that is used on the seals of the toilet will do it or you could try rubbing cooking oil into the rubber that's what I used which seems to have worked. Also you may be able to move the window latches inwards a little to make the window fit tighter, I have not done this but the engineer advised it. I wouldn't worry about it too much but keep an eye on it if it gets worse you may need to change the window rubber but at around a tenner a metre and around 6 metres needed from Seals Direct if you choose to do this you require the 30mm rubber with the larger 13mm bubble.
Pixie Hex the reason you have not had this issue is likely to be because a challenger has 3 windows so don't flex in transit
------------- its our imperfections that makes us perfect
You could see just how well the window is sealing onto the rubber seals by inserting a little strip of paper between them and closing it, now pull on the strip gently and see if it's tight or not.
Try this at various intervals around the leaking window to see if there is indeed a gap somewhere.
Also:-
Spray seal with silcone lubricant then plump up seal with fingers where it is leaking & try again.
I find it good to open all windows twice a year & spray seal all round with silicone spray. You will find silicone spray in Halfords etc with all the other spray lubricants.
Use only silicone because it is not oil based so ok on rubber.
Regards James
------------- In the beginning there was darkness.
Then I bought a tent.
I'm not destitute, I'm just poor.
Thanks for the responses on a closer inspection it looks like the seal on along the top of the window is not fully in contact with the window. I only brought this caravan 2 weeks ago from a dealer so will be in touch with them tomorrow and see about getting it sorted.
Is it a Swift, by any chance? we bought a Swift about 18 month ago it was used and from a dealer, it was still under the manufacturers water ingress warrantee, while onsite I was sat at the window and a gust of wind blew in through a gap around the closed front middle window, I took it back to the dealer and they said it was a common occurrence for the window to bow, it was replaced under warrantee.