I got to my friends house last night and a lovly green stream of colant started to flow from under my car.

It was the coolant fill system cap.
I had just replaced the cap and the o-ring, and it started to leak again 2 weeks later.

Do you think I need to replace the black peice that the cap fits onto?

 

Check nad see if you dont have a blown coolant seal.

 

Are you sure it is the cap and not flow from the over flow tube? The resevoir should only fill about 1/2, there is a mark on the side of the tank.

Over flow suggest it is overheating. Check thermostat, flush radiator and don't discount a blown seal.

 

When you say coolant fill cap are you talking about the pressure cap?

If thats what you're talking about, what did you replace it with? Don't use a Stant or some other wal-mart brand cap, get one from Mazda.

 

Im sure its the cap, its leaking out from it..... big puddle of antifreeze was sitting on the air pump.

And the cap is the upper one, right above the air pump comming from the water pump (or back?).

I just replaced it with one from autozone and it worked great for 2 wks. Dunno whats with it?