Kinda weird issue. My rear wiper reservoir seems to be partially clogged. I pour about 2-3 ounces of fluid in and in starts to overflow. After about 30 minutes I can use the fluid but if I activate the spray prior to that, I hear pump noise but nothing comes out. 

 

Anyone experienced this before? Any solutions (pun intended) out there?

Pull the reservoir, remove pump, half fill with course sand, shake vigorously until the tank is clean of any scale. 

Flush out sand ensuring there’s no remaining particles in there. 

Check pump to make sure it’s not clogged. 

Replace, test. 

Cheers 

Bennie

not sure about the overflowing....

 

I have used ice cubes , shaken vigorously, to clean the radiator overflow.