Coolant Leak. Radiator?

[ShamShield]

Hey everyone, new to the forums (and to Audi's as well). Need some help identifying a coolant leak coming from the front of my 03 Audi A4 1.8T (B6). I first noticed it a few days ago when I saw white smoke coming out of the engine compartment that had the smell of coolant to it. Checked the coolant level and it looked fine. The next day, I left the car running in my driveway for a little while, about 10-15 minutes or so, and noticed a small puddle of coolant under the front bumper. Coolant level was very low. Put the car up on ramps today and noticed that the coolant is dripping off the lip of the bumper under the radiator. I have a feeling it's from the radiator but I'm not too familiar with these cars yet so I thought I'd get some second opinions before I go replacing the thing. Thanks!

[KHARDa4]

Could be the rad or supply and return coolant hoses. I never played the guessing game, put a coolant pressure tester on it and see exactly where it's leaking from. Could possibly be the water pump. Pull the upper timing cover off and see if it is. Good luck!

[refueler]

I agree make sure its not the coolant pump before driving any more because if it is the pump that's leaking your not far from failure and that can have very bad consequences.

[ShamShield]

So I determined that the leak was in fact a crack in the radiator. Put in a new one, flushed out the old coolant, no more leak. But now I don't have heat. I bled the system of air pockets, so I'm assuming it's the heater core.

[refueler]

Did you have heat before you drained the coolant to replace the radiator.

[diagnosticator]

Not enough time was allowed for the cooling system and heater to completely fill naturally. The cooling system and heater will slowly fill with coolant from the expansion tank, but it takes about one hour to happen. Just let the car sit with the tank full, and refill the tank as the coolant slowly drains into the engine. Eventually, the coolant level in the tank will stop falling. At that point, replace the tank cap and run the engine at ~2000 RPM for several minutes. Next, turn the engine OFF and allow the engine to cool down to about ambient temp. Do Not loosen or remove the tank cap until the engine and coolant have cooled down to ambient temperature. Then top up the expansion tank with coolant as needed. Replace and tighten the tank cap, then test drive the car.

It can't hurt to open the bleeder screw in the hard pipe and bleed any air from the heater hose/pipe, but I have never needed to do this when allowing an hour for the system to slowly fill naturally. I have never had the heater trap air and not work after refilling the cooling system using the procedure described.

[ShamShield]

Not enough time was allowed for the cooling system and heater to completely fill naturally. The cooling system and heater will slowly fill with coolant from the expansion tank, but it takes about one hour to happen. Just let the car sit with the tank full, and refill the tank as the coolant slowly drains into the engine. Eventually, the coolant level in the tank will stop falling. At that point, replace the tank cap and run the engine at ~2000 RPM for several minutes. Next, turn the engine OFF and allow the engine to cool down to about ambient temp. Do Not loosen or remove the tank cap until the engine and coolant have cooled down to ambient temperature. Then top up the expansion tank with coolant as needed. Replace and tighten the tank cap, then test drive the car.

It can't hurt to open the bleeder screw in the hard pipe and bleed any air from the heater hose/pipe, but I have never needed to do this when allowing an hour for the system to slowly fill naturally. I have never had the heater trap air and not work after refilling the cooling system using the procedure described.

Did this, also read that bleeding air from the heater core outlet hose may help, but I haven't made much progress. Now it seems that the heat starts to work around 2000 rpms, but once I go back to idle it goes away. I'll give this another shot later this week when I have more time; it might just be that I'm frustrated and rushing through the process so it's not being done properly. I appreciate the help guys.