Got a low screenwash level warning today on the car, thought it had been filled only last week when the car was serviced but wasn’t sure so filled it up. 

Been out for a drive this evening and parking up at home noticed a damp patch on the ground, with screenwash smell. So topped the system up again, and it took maybe 1/4L or so. 

Checked below the car and shortly after the top-up it started leaking out at the rear of the wheelarch liner. 

Expecting this is the common issue with the seal between the main tank and the secondary tank leaking?

Just curious why it would only start leaking again after I’d topped it up with a small amount of fluid. 

Know there’s also cases where the tank can syphon itself out of the overflow if overfilled but I did a mod many years ago to add extra pipe to this and it’s been fine ever since. Always fill the system till there is fluid visible in the filler neck. 

Anyone got thoughts on this?

Thanks

Got this sorted but not the way I’d expected. 
 

Bought a new seal for the auxiliary tank connection to the main reservoir and fitted it this afternoon. Fiddly getting wheelarch liner off due to my mudflaps getting in the way. Could see some residue around the joint so reckoned that was the problem. Though when I disconnected the aux tank a load of screenwash came out 🤔

Got the old seal out anyhow and it looks different than the replacement even though they both have the same part number on them. 
 

 

vs

Can only guess the original has swelled over time?

Anyhow got seal fitted, aux tank reconnected, filled with fluid and after a minute or 2 it started leaking. From the aux tank 😳

So had to remove the leafscreen to have a look at the breather etc and more screenwash leaked out as I took the breather out of the aux tank. Seemed that the neck of the tank was off centre possibly partially dislodging the breather bung and letting the tank leak when the level was high enough to rise into the breather (which isn’t the highest part of the system). Managed to slacken off the tank and get the neck more central - one bolt not mega tight in the wheel arch area might have allowed the tank to move slightly. 
 

All seemed ok once I refilled everything so hopefully sorted now.