Talk to someone who knows about the chemistry of metals. You have a cooling system that is a bi/tri-metal environment immersed in a water based solution. I'm quite sure that Audi knows this and has done their homework. It is MHO that the issues with the cooling systems on these cars are probably due to the use of non-G12 coolant.

 

...I am VERY interested in how LONG your current heating capacity lasts. We may just be able to establish a set of symptoms verifiable by several users in order to predict the REAL cause of our problems to future sufferers.

My heat "came back" to some extent after I, and then the shop, flushed my core. I myself collected TONS of sandy and flaky crap into my flush bucket, and the shop soaked it for a while in cleaning solution before their final flush.

Heat came back (only when swapping heater hoses at the core), but that was a couple of months ago, and now at 20 deg outside, I can't tell if it's diminished again, or just wasn't really up to the task after all that work to begin with.

You took the first obvious step and I hope it works out for you!

 

Is is possible to snake the heater core? Or at least part of it? Would a radiator shop be able to do something? Pressure washer maybe? Just shooting wildly at ideas.

No one has gone so far as to swap the core yet, have they???

 

I think the C5 A6 forum has a bit "better" info on the heater woes, and there's a guy there who HAS swapped cores, and says it's not the end of the world, very do-able, just a bit involved, and most of us get scared away when we have to deal with interior panels and such, plastic breaking, clips lost, forgetting where plugs go, etc. But I'm going to suck it up and do it this summer.

 

Absolutely not....flat, very close tolerance passages, for maximum heat transfer efficiency...the same thing that lets em clog so easily IF something really stupid is done, like ever using stop-leak or ever mixing ANYTHING (no matter what the label claims) with G-12.

 

the heat has been working good enough to keep me satisfied. It's still no where near as hot as my A4 1.8T & my A6 3.0 were, but I'll get by.

Anyhow, this is off the subject, but I did get the torque converter replaced... I bought one from 517 Transmissions. They had very fast shipping & a reasonable price. I sent the core in today so that I could get my $300 back. I am happy so far since the dealers quote was $3600!!!! I had the new one put in by a local shop who specializes in after market upgrades to VW products. I was only charged $600 labor + $48 for fluids! So, I'm looking at a grand total of about $1252 for the total cost! I'm very happy with that. My normal mechanic, who is very good wanted about $1700 for the labor(he was quoting rack rate + what the book says as far as how long it will take). Anyhow, if you are in the northern Illinois area, go to Autohaus in Machesney Park. Tim is very fair & knowledgable about Audi/VW cars. He knew about how long it would take him & quoted me $600 labor before doing the job. When I picked up the car, he stuck with that price. Nice guy! Highly recommended!

I'm likely going to be doing airbags next... I've talked with him & again, he quoted me an awesome price & also offered to change the ride height if I wished for that. I'll do some research before I decide on that change... I don't want to drastically change the comfort of the ride.

 

The heaters in these cars will get clogged up IF its had coolant issues, like mixed coolant, hard water mixed in the coolant or any other debris from major service work performed in the past. These cars need to use G12 or G12+ coolant mixed with distilled water for long term performance and to prevent any build up. Also, if you have a clogged heater core, the heater hoses need to be bypassed and the system ran with the heater core to allow any debris to bypass the heater circuit. I would then pull the thermostat out and the radiator hoses and back flush the entire cooling system and lines with tap water to remove any debris or crude in the system. I have seen new heater cores get clogged within days of installation because there's crude trapped in heater coolant circuit. Once the flow diminishes through the heater core, the remaining crude stays in the lines. If you install a new heater core, the remaining crude in the system flows right into a free flowing heater core and clogs is shortly after. Some have had success also by using a bucket, pump and some hoses and running CLR backwards through the original heater core for an hour or so to clean up the heater core. This should remove a mineral deposits in the core and bring the heat back where it should be. All in all, when adding or replacing coolant, use the correct coolant and get some distilled water. You will appreciate it in the long run.

 

[QUOTE=ezveedub;24262982] Also, if you have a clogged heater core, the heater hoses need to be bypassed and the system ran with the heater core to allow any debris to bypass the heater circuit. I would then pull the thermostat out and the radiator hoses and back flush the entire cooling system and lines with tap water to remove any debris or crude in the system. QUOTE]

This sounds rational, and is the general idea to attach a garden hose (using one of those Prestone hose-attach couplings, somehow)to the system and flush everything out thru a low point, like the bottom of the radiator?

 

Ezeedub,

I am running only G12 & distilled water. I bought the car with 81,000 miles, so I can't speak for what was put in it before I bought it. I didn't run CLR through it, but I will when winter goes away & I have the patience. As for now, it's keeping my windshield clear & me warm.

 

[QUOTE=brider;24263352]I would say to just disconnect the hoses at the heater core and put a garden hose into heater hose that has the bleeder hole. No need to install a flush kit. No need to modify your heater hoses for a simple flush out. I would also remove the lower radiator hose or better, remove the thermostat and flush the block with running water. Remove the top radiator hose and also flush the block from the top hose also and also the radiator.

As for the heater core, you could get some extra regular heater hose and connect it to the heater core and fill it with CLR and let it soak. Just make sure its filled, so attach two hoses to it and hold them upwards higher than the heater core ports so you can allow the CLR to completely fill the core and let it soak. Then flush it out in reverse flow with a garden hose. If you have access to compressed air, I would give it a few blasts in reverse flow also before reconnecting it back to the cooling system. Then see if the heater core performance is improved. Just make sure you flush out all of the CLR before hooking it back up. You don't want that stuff flowing through your coolant system.