Mister Bally

I wondered how long it was going to take for you to reply. My outrageous suggestion was mainly in response to Mishar's comment how people should be fired for PPD (Pi$$ Poor Design) related to the service aspect of these vehicles. Just because the price of admission is so high should not mean the cost of ongoing ownership should be so high. Even the sales publications/website/other marketing stuff emphasizes how reliable and durable these overpriced sewing machines (a line from the movie Hollywood Knights) are. I've taken that to heart with my previous Audi's ('81 4000 5+5 and '87 5000CS quattro) which I had until they had 225,000 and 286,000 miles on the clock before donating them to a charity motors organization.

I never had to remove the engine on either of them and I replaced all sorts of sensors and assemblies. Ditto for the six different VW's with the exception of my first Beetle where the engine came out (30 minute job Removal and replacement) for a clutch job. Both other Audi's required clutch work which required tranny removal which wasn't so bad as I did it with two floor jacks.

As for the OP asking about a reliable Detroit area independent; Adolf & Gunther's Senger Motors on Tireman just East of Wyoming on the Dearborn-Detroit border is the most honest & comprehensive shop in the area. That said, they started out exclusively repairing VW's. Not sure if they do Audi repairs but I moved out of the ghetto nearby 30 years ago. They are still in business. Probably 2nd generation now but it can't hurt to give them a call. If you need to go to the dealer route; Howard Cooper VW/Porsche/Audi/Honda has the most honest dealer service department I have ever enCOuNterd. They even disCOuNt parts which is unusual.

Kpj

Thanks again for the recommendations. I just heard back from the dealer & they are quoting me $2K for the fix. They said that the part is not expensive, but the job is labor intensive.

This is 'less' than what I imagined, but still a crazy amount just to replace a coolant/temp sensor. I'm trying to find a reputable place to buy the Bentley Publisher A8 repair guilde/manual to see if it's something a DIYer can tackle.

Mr. Bally: I will give those places a call now to see if they can help me with my problem.

MP4.2 + 6.0: Is there any way you can send me those diagrams/pics of the area that would have to be accessed? It would be greatly appreciated.

Thanks again guys, it's nice to have a great community to correspond with.

Jeff-AudiUSAParts

I'm sure you've thought of this already, but I'd ask them to replace other sensors and/or o rings to sensors so long as they have the engine out. Pay a little extra now and possibly save a lot later kind of thing.

mishar

It looks like it is just behind a cylinder head, probably on both sides. If there is same space as with V8 engine it can be done without removing engine. No drilling of the firewall either.

MP4.2+6.0

are the O2 sensors. From old RS6 postings, I know that was a big gripe w/ that specific motor set up. I think some of them are engine removal access only; would have to look at the manual. Trouble is on a W12 there are lots of them (8 total?, though four would be post cats).

MP4.2+6.0

the key diagram looks like mishar's post. What is down in the lower right appears to be the tranny area bolt up. Should be only one sensor; that's the C5 4.2 set up (with two heads) I have dealt with before, the norm, and the electrical schematic is only indicating one.

As I mentioned before, if you want to try this w/out engine removal, I would get the part, find it by comparison and actual visual confirmation on the motor, and then assess realistically if by taking off the intake manifold (both the outer parts but also the part at the center of the "V" (W)), you could likely get at it--I think it will come down to clamp access, the wire connector access, and the ability to pull off the hoses attached. I suspect removing the intake manifold will give you much cleaner access to that rear head area from what I can see. I see no way to reach it from the fender side--just no clearance and then the exhaust and cats are lower down which will make it a big no go from underneath--or from the top--a bunch of what are probably AC (and other) lines right at the top for starters, and it's already tight. That manifold is really bulky too and really goes far back toward the firewall.

mishar

I think it must be accessible from the left fender side.

MP4.2+6.0

it doesn't show the issue in that case. Notice how on the more obviously visible side they show the motor with the exhaust manifold completely removed--you just see the head studs protruding. Thus imagine same thing on the side with the sensor. What is really there is a very large exhaust manifold toward the rear just barely clearing the motor mount, and then with the whole second exhaust (from the front three cylinders--there are really two exhaust manifolds per side) passing under the first and with its forward converter up in there too. You really can't even see it from above since there is no real working room. Again, removing the outer portion of the intake might help--W12's use a multipiece intake (the dual sides, the merging area joining from the outer runners, and then a riser under that attaching to the heads). The W motor is very shallow front to back, but it is hugely wide, so its really jammed on the sides once you get back to the wheel well area--air boxes are forward of that. I know from looking at mine there is no room up high to get in there--aluminum lines are between the motor and the firewall up high, which are likely freon; certainly totally inflexible. There is also an aluminum honeycomb heat shield about half way from the motor to the firewall--call it about 1" in a space just over 2 inches total, but full of hoses and wires and such. The heat shield looks huge and wraps around the back and sides of the motor. I bet it only comes out after the motor is out, ...unless we take Mister Bally's demo saw to it...

FWIW, here is an illustration of the W12 exhaust. And, because the illustration doesn't show the heads, it also doesn't show the chain cam drive, all of which is back there and puts the work area probably right about where the converter for the rear left exhaust manifold broadens out to full width

MP4.2+6.0

of the gawd awful situation the OP is contending with--first one below is from pretty much directly above. The straight edge is resting on the top of the intake manifold; about 2 1/2 total inches before contending with any of the gazillion obstructions.

All the crap on top behind the manifold looks about unremovium just for starters--not just simple vapor or water lines in general. Then notice on the far right you can just kind of extend the line forward where you see the plenum area gasket making its sweep forward; that's the shock tower sheet metal area (hmmm...another Bally demo saw "access" opportunity??). Down in the shadows you can just make out the back edge of the cylinder head valve cover--the aluminum looking piece partially shadowed by a black breather looking hose running side to side. The valve cover (and head below it) protrudes even more to the rear than the intake manifold does, and it is way below the top surface of the manifold--and that sensor in question is even lower down from the diagram.

Thus, the one place I can see to open up a little more access is from the center of the V (W), which nets to pulling the whole intake. See the second picture where all I did was take off the plastic trim piece in the center of the intake (which is what you see in my auto sig picture); you see the center of the V down low, so imagine that coming out to open up access from that side of the head. Then the next (and final) piece that might help removing if needed is the valve cover itself. Also way easier than pulling an exhaust manifold, which at least on my C5 4.2 seemed to only be removable by pulling the head after dropping the head pipe (BTDT). Could be more space for a 4.2 under the wide D3 body, but the W12 motor is a lot wider overall than the 4.2.

mishar

Now tell me that chief engineer shouldn't be fired. Hi is one who should coordinate engine and body design. That sensor could be at ten different spots, body could be 5" further. There is nothing right behind that wall.

I think that exhaust manifold won't be problem. Sensor should be above it (first picture). Can you peak from little bit closer to the left fender. Use mirror if possible. If there is enough room for one hand there is hope. Alternative is bad. It is not only $2000. I would be scared to let those guys to take engine and transmission out and put it back. Instruction for that job took me a minute just to scroll it. You have to take everything apart. Even vipers. I bet they do not have all plastic parts they are going to brake. It can last months to get all that.

May be Mister Bally has some idea involving those pipes, hoses and jig saw.