No heat at idle after some soft of coolant flush/drain/change/treatment? Here is fix

[nimski62]

If you have tried everything, bled the system 2-3 times using the bleed valve located at the bottom of the engine, and are extremely frustrated and want to replace the heater core.. dont do it, its just a finnicky heater core air pocket.

The heater core generally only gets pressure when the car is revved up, because it is a passive system (i think), if there is any sort of air pocket, it wont leave through the hose for some reason, and needs to be bled properly.


There are two coolant hoses on the firewall directly next to the battery for the heater core.




The right hose(outlet) has a bleed hole on it. The hose needs to be pulled part way out, until the bleed hole is exposed.. you can see the tiny hole in the pic, ignore the numbers i borrowed this pic

Once the hose is pulled out to the point of the little hole being exposed to coolant, rev the engine up to 3-4k for 3-5 minutes. There will be coolant loss, and YOU ARE NOT DONE at the first sign of coolant through the little hole.. Keep going. For a while. And have someone push the hose in while the engine is still revved up after 3-5 min. (be careful here, as it can be HOTTT).

IF THIS DOES NOT FIX YOUR PROBLEM, REPEAT.

[Leeer73]

Thanks for the info! so the "hole" would be were the # 2 is in the picture right?

I have a question that maybe you can answer! I changed my timing belt about 2-3 months ago and had to drain some of the coolant in the process. When I refilled it, I did not bleed the system at all and since then my temp guage only works periodically. Do you think a bubbe in the system would make my temp guage act like that?

Thanks for any info you might have!

[nimski62]

Thanks for the info! so the "hole" would be were the # 2 is in the picture right?

I have a question that maybe you can answer! I changed my timing belt about 2-3 months ago and had to drain some of the coolant in the process. When I refilled it, I did not bleed the system at all and since then my temp guage only works periodically. Do you think a bubbe in the system would make my temp guage act like that?

Thanks for any info you might have!

As long as you're not over heating, I don't think you have an air pocket in the cooling system, but if you don't have heat at idle, you may have an air pocket in the heater core. Your temp sensor might also be faulty.

[s42k5b]

Your CTS could be faulty like nimski62 said or it could be a T-stat issue.

[V8weight]

you could still have an air pocket right at the cts. Air likes to rise to the top. start the car and bring it up to full temp, then loosen the cts, allowing any possible air to escape. keep it loose until you have a steady stream of coolant running out of the threads. watch your eyes.

[DoGGRoBBer]

The heater core in our Audi's will clog up over time. With the hoses removed in Pic. use a degreaser, and spray it into the inlet to the heater core. Allow the degreaser to break down the sludge that is built up. then flush with freash water. Repeat 2-3 more times to flush heater core. I know its a vaige description, but you should get the idea.


Sorry again...its late and I'm drunk...
LOL

[Leeer73]

Thanks for the info guys!

@V8weight, where is that CTS located? Is it hard to get to? I got the 2.8.