awdinut

My W12 blew a coolant hose 3 wks ago while I was sitting in a parking lot (fortunately) in single digit weather. I told the shop to also change out any other coolant lines or hoses that have not already been changed because I never want to get towed in for a coolant issue again. The hoses had to come from Germany and got here this week finally. The one you see cost $300 and there is another hose not quite as complex that is $200. The labor est is $800. Expensive hoses, but I am just thankful that they are still available...I dont think that what you see here could be replaced by straight hose stock. The rarity of the W12 A8 gives a scary side to ownership.

TSHong

I still like driving may car as a DD but this is why I'm starting investigate my next car. I had a hose that has some scaling so I replaced it on my timeline. $700+ for a wiper motor and I'm glad I was able to get one.

MP4.2+6.0

I just changed that hose on what is now my brother in law's W12 when we did the thermostat. Just got it back on road. My old W12 is pre- a mysterious VIN split during the 2006 MY--it was built way back in April 2005. Changes are apparently in some of cooling system layout and maybe in the fuel rail--which came up when we pulled it to get at thermostat and then found fuel injector fiber tips were all rotting away. Those all got replaced too, along with the clearly arcing coil packs that were not throwing codes. 173K+ miles, with prior recall change on coil packs BTW. Injectors original.

For mine that hose shows as no longer available--assuming the big end goes to upper main radiator. My part # is 4E0121101AM. We managed to get it shipped from Lithuania as NOS for about $100. Took three + weeks, though frankly it got here quicker than stuff I ordered from audiusaparts, who are now on the outs with me from several recent disappointments. Also found audioemparts.com, aka Audi Henderson NV, is cheaper from parts bought in just last day after audiusaparts muffed it yet again. No more audiusaparts for me until they get their act together--and also clean up small part pricing, ship miscues and general web/email lackadaisical approach I saw a bunch of times over last 45 days.

FWIW, likewise we changed anything that was older that we could get that looked swollen. That particular one is also problematic because it has those various plastic bits in it that seem to rot in smaller sizes after about a dozen years. I had previously replaced a smaller section of that assembly when the Y fell apart. On latest round, I also did the main thermostat upper hose, which is still available. It was somewhat swollen. It might look inaccessible under upper intake manifold, but it uses a metal clip (just like radiator side of the upper hose we both did does) so can be pulled and replaced. I also found the modest sized hose to its right that goes laterally to a metal pipe is not longer available for pre-VIN split like mine. Six months ago (summer heat) it also blew one of the hoses back at the heater valve block under the cowl. That was original too and still available. Had been patched with heater hose length in meantime. We put new one in. From our work winter heat is now strong...when motor is revved up on road. Why we did all the thermostats, including cartridge one back in coolant line by the tranny and gear oil coolers. Heat still goes lukewarm at idle--but cooks shoe leather on highway--so I am busy getting a used valve block. At < = $150 from Europe shipped, I will take my chances compared to the $1800 "discounted" dealer replacement. For trivia there, my car has the "A" block, while current interchangeable one is a "C". Side note on new main thermostat we used: took a chance on rockauto's listing of all things...for a W12!... Figured we could return up front if it looked subpar, but it appears to be OES including markings--I knew appearance and construction close up from a prior change. Hundreds less than discounted Audi dealer.

The one interesting new (for me) cooling system discovery during our work and hose odyssey is a third thermostat I never really realized was there. It is down with the lower auxiliary radiator--just looks like a non descript small can in a T intersection of a hose assembly. It then isolates that cooler if cold, or brings it on line for high temps. Many times I thought it was just some smog air line with a muffler until I realized where it went when I looked at hose ends. First time I ever changed that, and I only found it because a body shop doing modest work from a parking block incident missed the mispositioned cooler and likely stressed a related hose at clamp point to where it slightly tore. Those hoses had some swelling at some ends too.

Finally for both you and TS Hong, last year mine also had another cracked coolant overflow line--the one back behind the intake area close to forward firewall. That was second replacement. In both cases I think some mediocre shop work by guys unfamiliar with it led to it getting stressed and cracked. We also cracked the extension of it up above radiator that heads to the hose in your picture. Using some leftover over hose bits and Audi looking pinch clamps I made up a factory looking splice for now rather than replacing. But it's a head's up to watch that whole overflow hose assembly (two different runs and parts) for even a second round of replacememt. That can lead to on the road issues, though it tends to first show up as a small coolant leak that takes a while to track down.

awdinut

Thanks, as always, for taking the time to recount your W12 experiences at length. Last year the fire wall/heater hose in my car went out as well, along with the attendant plastic bit. And also last year the plastic tube line to the coolant bottle...hence my wanting to replace everything left while they have it at the shop. I hate having my W12 in the hands of others if it can be avoided; not to mention the trauma of loading and unloading on the flat bed.

MP4.2+6.0

Yep, figured I would document the field experience on W12 18 years/175K in, especially since I still know whole history since new. No one at indy shops really knows any of this kind of stuff here in the 8MM resident Bay Area (only know Tesla's it seems now...kinda maybe...but happy to pick up the dollars falling out of owners' pockets), parts sourcing is now harder and increasingly farther afield, etc. Motivated me to get into some other old codes and try to clean up too--motorized rear door shade that won't stay down (bad door controller?), one bad park sensor, the lukewarm heat at idle (seems like valve block now), and recent rear brake wear light even though pads look okay (about to change pads anyway and run park brake motor in and out yet more, check calibration, etc.)

awdinut

No one at the 2 Audi dealerships here in KC know anything about a W12 either; these cars are so rare that almost no shop has seen one. The indy shop I use has 3 former Audi dealer techs and one of them has some experience on Phaeton W12 engines from his days at an Audi/VW dealership but for the most part they are going to school on my car. But I wouldnt be any better-off at the dealer because they would also be going to school and I would be paying twice the hourly tuition for them.

If you ever get stumped sourcing a part, Mr E, I have a connection with the part guy at the Kaiserschlaten Audi dealership in Germany. He will sell me anything available in Germany and personally arrange shipping to me here in the US. I have a great deal of non-US market options in my car and he has also been a great resource of part number knowledge to facilitate my acquisitions.

And BTW my car has 163K, so our two W12s are apples-to-apples in that regard. Like 'your' W12, mine probably needs injectors and coil packs, but what ever they cost...times 12...is more money that I will have. Especially after $4K+ for the hoses and front bushings !

MP4.2+6.0

Thanks. Will keep in mind if ever stumped. FWIW in this latest round, I also found another Euro parts diagram site that has the yet more detailed parts slides than parts.audiusa typically use. A bit cumbersome on interface, but diagrams are a lot better and close to reality instead of the USA schematic style. https://www.lllparts.co.uk/catalogs/audi/USA/A8Q/291. Coolant hose diagrams used in USA sites for example are almost gibberish schematically, and I have learned to try to get a picture off any hose part that is quasi legible still.

FWIW, both coil packs and injectors are easily found in independent channels. FCP, Rock Auto, Autohausaz, ECS (pricier usually), and others. The coil packs are offered in Bosch, NGK, Delphi and some others. Injectors I got are Bosch branded and have the Audi part #'s right on them, just like the OE ones I pulled have the same Bosch # (never updated as a part #). I got both via FCP Euro w/ a year end sale at certain discount steps, but they can be found elsewhere near same sale price. We did it as part of spark plug and thermostat replace; best to combine with a job already needing upper intake pull anyway. Thermostat requires all the way down to an injector and fuel rail pull on the ones like mine where the fuel rail is direclty above some key lower intake riser bolts that come out to get to thermostat under that riser. The clips that hold the injectors to the rail are such that you have to remove it all to then access the metal retainer clips--rail doesn't come out by itself on my motor. Thus, definitely a job to roll in together. The plug and injector wiring harness are also tightly intertwined, and injectors yet another one off unusual lock clip that is not intuitive or well documented.