coolant/ fan issue! please help.

[a1rh3adSz]

Hi, guys i need some help going to try to explain this the best i can. car is an 02 b6 a4 1.8t 5sp quattro 98k miles. Timing belt water pump t-stat was done between 85 to 95k miles ago by previous owner.
this sound like an on and off thing. I am not losing coolant like a leak or anything that i know of, but when i start to drive cold start it takes a while for the temp gauge to reach middle. It would rise and drop depending if i am idling or driving, it mostly stay half way between cold and middle. But if i drive for a while and then let it idle it would reach middle needle position and i can smell coolant and when i open the hood coolant tank would be boiling or bubbling. Then you would see a steam of white smoke coming out, that is when i lose coolant from the overflow area. once it cools down then its fine. when it hits the middle position it does take a while before the problem starts. Sometimes before the issue i can see a little white vapor steam from the drive headlights area.

what can it be? need a new water pump/ t stat/ Cts/ ??

Oh and this happen just yesterday never happen before. cold start both fans come on for like maybe 3 to 5mins then goes off. and if i shut the car off right away fan goes off too..

please help. thanks.

[old guy]

The fans running on a cold start are the result of a cooling system malfunction. The ECM knows something is wrong so the default position is to provide maximum cooling to prevent engine damage.

Read through this thread Clicky click® It contains a lot of diagnostic information that you can use to help determine your problem and also to learn a little about how a mapped cooling system functions.