Motor wise Do a comp test and a leak down test. Expect with the cold motor to get not great leak down but the comp test can be ran by hot jumping the starter. I’d do this post the numbers and then lean on that data to move forward.
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I agree with Justin in doing a Compression and leakdown test. Also, if you don’t have a video borescope then buy a cheap Amazon one that hooks to your Iphone or Android, they have pretty good pictures now and you can inspect the bores, they even come with the reflection mirror attachment so you can see the head of the valves. Just make sure the head is small enough to fit through the Sparkplug hole.
Personally I wouldn’t do anything to the engine until you have had it swapped over and running. A running project will get worked on, a project that becomes a rabbit hole will end up unfinished
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I appreciate your thoughts guys! I’ll go as deep as taking the cam plates off to replace the weepy spark plug wells, and leave anything deeper for later, or never.
Just get the damn motor in the damn car
That’s a lot of work getting it all in the car just to find out something with the motor is wrong, At least inspect the cylinders. Take a look at the S6 engine post just above yours. Better to find out now than later.
I think my biggest hurdle ahead is fab work fitting powertrain and exhaust into the B5. To Kaclaytor’s point the sooner I get to that the better which makes sense to me to avoid project creep. However I’ll take some precautions to check health. I have a borescope I’ll do some investigating with and leak down test. Not sure if a compression test is feasible in the engine’s current state.
You have never done a project like this have you? Pulling the engine in and out isn’t a big deal. Getting the engine swapped and running is the hurdle. Pulling the motor once that is all taken care of is nothing.
Well, between my 8 vehicles I’ll narrow it down to the two most recent swaps, a C5 RS6 and a B8.5 RS5 that I’ve had and engine out and in each twice. I know exactly what kind of work it is. But just bolting it in isn’t the same as getting a driveline, electrical, cooling, ECU, etc… all hooked up just to find out that the cylinders are scored or it needs Rod or Main bearings. Why wait until it is in and have to do the work twice?? The post above with the guy who’s on his second engine (V10) which looks like it has issues and with similar mileage to the poster. Following Audi’s factory Mx intervals doesn’t leave a healthy engine at 150k miles. I’ll just see what happens from here on out, but I’d at least throw a set of fresh Rod bearings in since the V10 has been known to occasioanlly eat Rod bearings.
You have never done a project like this have you?
Guilty. I’ve pulled and dropped in motors before but this is my first cross-platform swap I’ve taken on.
hahnmgh63 thank you its a valid point. Why put a motor in that’s not healthy? However, if for some reason this motor is toast I would just replace it with the exact same thing, still leaving driveline, electrical, cooling, ECU, etc… still to do. I know its running, but more thinking of the motor as a mock up piece for the project at this point.
Nevertheless, cylinder photos and leak down results incoming this weekend.
That comment wasnt meant for you. It was for Hahn. Keeping momentum on a large project is going to be key to getting it done. Taking on a full engine rebuild before even diving in is just going to empty your bank account and motivation. I can all but guarantee the engine will need to come back out for one reason or another before it is a fully running and driving car. For the first start the car isn’t going to be fully buttoned up. It will be no core support minimum components hooked up and you’d be able to pull it back out in under an hour. This is all just my opinion and based on taking on projects as a husband, father, with a full time job and side work. If you have nothing but free time and money obviously your path would be extremely different
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Agree with above. Get the engine and transmission situated. Martin Harp can get your immobilizer coded out and I can sent a pinout of the 8 or so wires that need to be connected for a first start.
Eventually get some coolant in it so you can run it long enough to see if there’s any abnormal smoking, or misfires. Then go from there. 
You got this bud!
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@Nordy1865 put together a great shopping list in a post on here for rebuilding the BXA V10. I present to you, my essentials list, based on what I think is worth replacing while the engine is out, but not trying to overhaul the motor. Call it a motor freshener.
Posting for others in the future who may end up where I am. I’ll probably make a google sheet link with copyable text and links later on in this thread, after more is compiled. Not a bad price tag for so many gaskets.
UPDATED SCREENSHOT: LINK TO SHEET
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This as about as deep as I plan on going with the motor. Currently cleaning out the heads. Rockers go in the ultrasonic cleaner. Tedius!
I’ve been jokingly calling work on this project “garage therapy” but man is it true. I had to take a month off to remedy my ‘85 Benz, and coming back to this felt so good. Ball is rolling again.
After ultrasonic cleaning rockers and hand cleaning heads, it was time to put the cam plates back on. I locked the cams in place with the tool, and used the zip tie method to hold cams onto the plate. Then nervously laid 2.5mm beads of VAG sealant in the 3 specc’d locations. I used 2 large phillips screwdrivers in the alignment holes for placement to the head. Shimmied down and then added the new hardware, hand tightening then waiting 30 minutes, and finally the 4 stage torquing sequence to 8nm+90. That was fun.
Next up, reassembling the rear of the motor, timing.
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Nice! That actually does look fun!
Super fun thread. Great work. Looking forward to watching this develop
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Inspiring!
I have started to tear into my S6 and preparing for the engine drop in my gravel driveway!
The Erwin manuals are a must!
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Awesome. It is a lot of time and patience, but it will be a joy to drive once you are done.
My engine has been great and has not developed any leaks.
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Crazy how a little bit of grinding and acetone make these rear timing covers weld up so nice and easy… thank God it’s not magnesium!!
I like how you used a slug vs me sitting there for 5 minutes filling it in with wire LOL.
Came out great dude!
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