coolant flange leak == car takes forever to heat up?

[a4wd]

Hey guys, so Ive been having a rear flange leak for a while now. On the cold morning during start ups, the car idles at 1K RPM rather than the 1.5K it should. This has happened when the coolant got low, and whenever I filled her back up, it would have a normal cold startup idle.

Now, I just hear the fan going crazy, and the car takes forever to warm up. Someone told me this could be due to my temp sensor going out. I have plans of taking to my mechanic, but I wanted to have all parts ready to go before I make my 45 min trak there. If anyone eles can chime in, it would be awesome

[lookaught]

I would try bleeding the air out of the top pipe. IIRC the temp sensor is in the coolant flange and is cheap, so it will be an easy fix once the mechanic gets the flange out.

[TheMadDutchman]

On the 1.8t I usually replace the coolant flange with the two hoses that are connected to it, the coolant temperature sensor, o-ring, and retainer clip. I would address those items before attempting to diagnose a cold start/driveability issue. Good luck!

[AudiA4_20T]

On the 1.8t I usually replace the coolant flange with the two hoses that are connected to it, the coolant temperature sensor, o-ring, and retainer clip. I would address those items before attempting to diagnose a cold start/driveability issue. Good luck!

good advice, if you do them all it should cover all the bases

[Audi Skate Snow]

cold start prolly isnt from a leaky flange...but for sure get that fix if its leaking.

Coolant temp sensor. (15 bucks from ESCtuning.com)

Or

Thermostat (110 bucks from ESCtuning.com)

those are prolly your two culprits for your cold start.