Anti freeze over flowing

make sure you got the proper rotation wp.
is it pulling in air anywhere?
did you burp the cooling system?

Sounds like the thermostat or air in the system

There are different rotations for a Ford water pump, you have standard as well as reverse rotation. Whats the parts number of the water pump you got? I'll second the notion that it sounds like excessive air in the system

There are only two things (aside from overheating) that cause the coolant to pump out of the radiator and into the overflow tank.

1. Head gasket blown between a cylinder and the water jacket.
High cylinder pressure from the compression stroke and combustion over pressurize the cooling system above the rated PSI of the radiator cap.

2. Weak radiator cap.
Normal coolant pressures overcome the spring of the weak radiator cap.

A radiator cap is actually a cap within a cap. The smaller inner gasket seals the system until pressure builds to what the cap is rated at, then the spring compresses and the inner cap lifts then allows expanding coolant to flow past it, down the overflow tube to the overflow tank.... while the larger outer gasket on the cap keeps coolant from leaking from around the top of the radiator neck.

If your car overheats or you have a blown head gasket, pressure in the cooling system will exceed the spring rate of the cap and fill the overflow.

If you have a weak/tired spring in the cap, it will be overcome before the cooling system even reaches the rated PSI indicated on the cap and pump the coolant into the overflow tank.

Drill a small hole in the 12 o'clock position on the tstat. This will help burp the system.

Bryan83taco said:

Drill a small hole in the 12 o'clock position on the tstat. This will help burp the system.

Click to expand...

Or just use a mr. gaskets 180, that's what i always have used and never had a single burping issue.
Just run the car with the cap off for 15 minutes and refill as the air comes out.

Capri also makes a good point with the radiator cap, they are only like $10, so when in doubt, just replace it.

open cap and run heat on high it will help get air out