When I fill up my windscreen washer bottle I get water pouring out the bottom of the car. I assumed this was a fault so I've removed the inner arch splash guard, the water is coming out of a 'cap' on the top of the bottle. It looks like its intended to this, am I missing something?

 

Has your car got headlight wipers/washers? If no, that is where the pump sits (IIRC).

 

No, it may have had at one time though. Is there another cap to seal that off?

 

That is a breather device to allow air to replace the pumped water. It should be a one-way valve that does not allow water out, but does allow air in. It is still available from Jaguar, see parts 7 and 8: https://www.jaguarclassicparts.com/u...sher-reservoir
By the way, you have the pump for the headlight washers, even if no washers!

 

Thanks. Chances are the valve is just stuck, I will pull it out at the weekend and examine it. The car may have had washers at one time, my understanding is that those parts are very hard to come by so they may have been removed if there was a f​​​ault.

 

The headlight washer pump mounts in the moulded depression down next to the other pump (hard to tell from pic on a mobile phone but it seems to be there). I think the air bleed valve mounts via a rubber grommet so it may just be perished to the point of not sealing.