If coolant is actually blowing out the reserve tank, it's being pressurized by compression from the engine. You probably have a blown head gasket or a crack/leak in the head. Have a compression test done to find out what the exact problem is.
Head gaskets seem to be a common problem with the PT.
Have a chemical block test done to see if you are getting exhaust fumes in the cooling system. You should not be using just water in the cooling system
Looking for a Used PT Cruiser in your area?
CarGurus has 1,376 nationwide PT Cruiser listings starting at $1,595.
Search Chrysler PT Cruiser Questions
Chrysler PT Cruiser Experts
#1Kelly Little AshfordReputation2,640
Find great deals from top-rated dealersTMSearch
Related Models For Sale
Used Cars for Sale