Coolant issue?

[Wah5000]

Hi Guys

When i took my car for a drive and got home, i notice coolant leaking quite abit.
When i popped the hood, i found the reserver overflowing. But after letting the car cool down, it was back to normal

Reserver was only half full b4 i went out 2.

Any1 know what would cause it to overflow like this

[accentstencil]

A new radiator cap will probably fix it.

[fkford]

ur resivour only overflows if ur car is over heating... probably losing pressure somewhere e.g a leak of some sort

[hako]

As accentstencil says, it will probably be the radiator cap - if the seal is dodgy, when the coolant cools down it usuaually is sucked back from the reservoir to the radiator...but if the radiator cap seal is buggered it will allow air to be sucked back into the radiator and next time you run the engine the air will expand at a greater rate than the coolant and displace or force coolant from the overflow tank.