Recently Flushed Coolant System, Cold / Warm Air Coming from Heater Core

[arjun90]

I recently flushed the coolant system on my Audi. I was under the impression that the vehicle would automatically bleed the coolant system. 200 Miles later, at 74 degrees Fahrenheit set on the control panel, the vents still blow cool air. If I raise the temperature up to 'HI' the air feels very warm, but feels more like how 74 degrees should be. I don't want to have to flush the coolant system again. What would be the way to correct this now? The heater core was working fine prior to the flush. I don't have any fault codes pertaining to the Coolant System.

Audi A6 (C5) Avant, 2004 (3.0T, Quattro) V6

[arjun90]

Do I just keep the reservoir cap off and run the car's engine for a few minutes?

[jcjohnson33]

You need to open the vents to purge all the air out


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[Robsa6]

There should be a bleed screw in the rear coolant crossover tube. Supposed to open this and let the car warm up to open the thermostat and let the cycling antifreeze push the air out. I've had to take the heater hose off my 97 a6 wagon to get heat after cooling system work though. It's very important to get the air pockets out though as a hot spot will do damage in the engine specifically around the combustion chambers

[arjun90]

Is there a bleed hole somewhere in one of the heater core hoses? Perhaps I need to expose the hole to let the bubbles out? What about removing the reservoir cap with the Engine and Heat On?

The Coolant Temperature Gauge is in the Middle at all times, and the Engine Temperature seems acceptable, two notches below 250 Fahrenheit, thus somewhere around 200-210.

There should be a bleed screw in the rear coolant crossover tube. Supposed to open this and let the car warm up to open the thermostat and let the cycling antifreeze push the air out. I've had to take the heater hose off my 97 a6 wagon to get heat after cooling system work though. It's very important to get the air pockets out though as a hot spot will do damage in the engine specifically around the combustion chambers

[Robsa6]

If you can get the reservoir up higher than the heater opening the lid should work as well but it has to be the highest point. Sounds like you've got the engine bled with air in the heater core.

[suth31]

i have a similar problem in my 2.7T. is there a bleeder someplace? a picture would help. thanks

[grmnmusl]

Just run car with heat on high and blower on med. Press ECONOMY button so the little red light is on (AC fan should be off when running) and with bottle cap off for 30 minutes.
Top off and close when heat is nice and hot and AC fan cycled twice. Done.

[Robsa6]

I actually had to drain my coolant last night and as I was putting the bumper back on I let the car run with the lid off and as the thermostat opened and closed the system burped several times and I topped off the reservoir and took it for a ride. I didn't get hot air until I drove it but I didn't have to burp it again but I did let it run 20 minutes or better while it cycled

[arjun90]

I didn't have to bleed the system much, perhaps I got lucky
I left the cap off for about 5-10 minutes, ran the RPM up to 2,500 every 30 seconds or so. Heat is consistent, I probably should let the engine run without the Coolant Reservoir cap for a longer duration but I don't have any more fresh Coolant from the Audi bottle; when the system burps, will I loose significant amount of coolant? How do I prevent coolant from spewing out out of the Coolant Reservoir?

[engineer73]

For the 2.7 guys not sure if the 3.0 is the same or not but if you stand in front of the car with hood opened and front engine cover off. Locate the throttle body and on the (right) drivers side of it at straight down towards the valley of the block you will see a metal black tube with a allen head on it, that is your coolant bleed screw. With engine running open it one turn CCW until coolant starts to spew out. That is the high side vent for the system and that's where the air will be trapped.

[suth31]

For the 2.7 guys not sure if the 3.0 is the same or not but if you stand in front of the car with hood opened and front engine cover off. Locate the throttle body and on the (right) drivers side of it at straight down towards the valley of the block you will see a metal black tube with a allen head on it, that is your coolant bleed screw. With engine running open it one turn CCW until coolant starts to spew out. That is the high side vent for the system and that's where the air will be trapped.

my bleed screw is corroded and looks like it is going to fall apart if I put a tool even near it. any suggestions on replacement?