My 2002 A4 has been without heat so this past weekend I used the tech article procedure and flushed my heater core. I used plain water until it ran clear. Connected everything and still did not have heat.

Doing some more research I found several posts recommending oxyclean and figured I had nothing to use. One of the posters worked at a VW dealer.

Bottom line is that I now have excellent heat.

Here is what I did:
Bought 12' of 3/4" id tubing at Lowes. 3/4" is not a good fit so I used a grinding stone and my drill to increase the ID of the hose. (7/8 tubing is what you need, but lowes didn't have it)I hooked a length to both the inlet and outlet of the heater core at the firewall.

I then boiled 3 gallons of water and ran that backwards through my heater core, adding a spoonful of oxyclean every couple of cups. I then flushed with the hose until it ran clear. I then hooked the hose up to the inlet and flushed in the normal direction of flow and was surprised at how much more gunk I got out. When it ran clear I backflushed again with water and just went back and forth (maybe 6 times) until I didn't get anything but clear water in either direction. I put a G12 mix into the heater core through those hoses(i was concerned about leaving plain water in the core in case I didn't get any flow)

Connected everything, bled the air out of the core and voila....excellent heat. I am a believer now.

 

When you initially did the oxyclean, did you simply gravity feed the "couple of cups" of oxi clean intially?