Mister Bally

Component protection is best removed by a dealer. Quick, simple and guaranteed.

There is someone who posts on here in Poland who can do it remotely if you have a proper diagnostic interface and PC connected to the internet. His fee is less than a dealer. Use google to find with AudiWorld as the first word in your search.

volvopentaman

So now I have come to the conclusion that it has to be the heater cores themselves clogging up. The problem only occurs at WOT kickdown. Cruising (who the hell just cruises a W12???) works for very long times.

I unclogged both heater cores 11.11.2018 at 271270km, and today 1.12.2018 at 271870km they were clogged again. In between a few (3-4) kickdowns and full accelerations from 70->140km/h.

The original part number is 4D0898030B (2008), there is a 4D0898030A number for older D3 (2004-2006) and D2facelift (1999-2003).

Most car spare part sellers want to sell a number 4D0819030 that just does not fit our cars at all. It fits D2 PRE-facelift cars 1995-1998. These are stupid cheap 22-60€/pc!!!

There is a brass/copper aftermarket version available for a reasonable 125€ in england
https://www.ebay.de/itm/Audi-A8-heater-matrix-2001-onwards-Quattro-sport-New-made-in-uk/292822566264?hash=item442d95c578:g:dGsAAOSw4Npayxl F:rk:13f:0

I'm at the moment thinking if i should get the aftermarket brass/copper for a direct bolt-on fit or a D2 aftermarket aluminium one and mod the hoses to fit (if the exchanger fits). The original ones at arund 400€/pc is just way too much when i'm not 100% sure the problem will be completely removed with this part.

volvopentaman

SOLVED.

Replaced heater cores a few weeks ago. Both clogged. Was a hard time blowing air through them by mouth. New exchangers from Motoradsonline Car Radiators | Car Heater matrix | Car Air Conditioning Condensers 125€/pc + shipping.

They are brass/copper and excellent quality. Instant heat and doesn't fade like the old ones always faded 2-4 weeks after cleaning or on first kickdown.

Installing was relatively easy, drop glovebox, move fan motor cable and air suspension ECU out of way, loosen 2 clamps and a securing screw and drain coolant.

Driver side remove trim below dash (the one with ignition lock and light switch), remove clamps and securing screw from heater core AND remove BRAKE PEDAL!

Be sure to install new hose clamps, as the old ones don't fit the new heater cores, and be sure to triple check the clamps are seated properly!

awdinut

Yea-a-a-a !! Glad to know you finally solved the mystery. There will no doubt be other AW members who will benefit from your R&D. My previous A8L (4.2) developed a low heat problem I never knew how to cure; maybe it was the heater cores. Flushing didnt help.

Now I have an 06 W12 with proper heat, but if that changes I will come back to this post.

dvs_dave

Glad you fixed it. But how did the heater cores keep getting blocked up? Where was the material that was blocking them coming from, and what’s to stop it happening again?

volvopentaman

The heater cores were fallng apart internally, and the corroding metal inside the heater cores was the one responsible for the clogging.

Had one of the cores out and rinsed it thoroughly with acid, but it only worked for a week or two.

I suspect the aluminium from the gasoline engine blocks is the one that is responsible for this corrosion along with neglecting coolant replacements. I suspect my coolant hadn't been replaced ever at the dealer Service before I bought the car.

Friends A8 2005 4,0TDI has no such issue as it has an iron block and we replaced the coolant in 2014.

ltooz_a6_a8_q7

I don't believe in corrosion since the core is always filled with anti freeze, unless the chemical does that. It doesn't matter how long or how many miles I've had on my Audi's, never once I had to fix the heater core, may be California cars are immune to corrosion.
Cheers,
Louis

Julian Allan

check out the pumps if the problem still there its better to check it by car mechanic GJ Drivelines is my go to shop from for parts or car service they are great