Plastic Coolant Tank! on 1998 Ford Ranger

my coolant only lasts a week or so before it needs to be filled again, How much would it cost to replace the Plastic tank!

Asked by for the 1998 Ford Ranger
Is the tank leaking? If the tank itself is not leaking, and the engine is consuming coolant, you've got a bigger problem and should take the car in to have the coolant loss diagnosed.