Coolant Leak

[CornersWell]

Looked around online, but I thought I'd throw this up for our learned community.

Noticed a leak the other day in the garage. Didn't think anything of it, because I have a leak from the ceiling. That's being repaired, of course, but the RS6 started throwing low coolant level warnings. So, parked the car and started digging a bit. Definitely a coolant leak from the car (and not water from the ceiling). Haven't pulled the under tray, so I can't see the origin, but source is at the right front of the engine compartment (and not the coolant tank).

My internet sleuthing is inconclusive. So, any suggestions are welcome. The good news is that I have a service slot at my Indy scheduled a couple of weeks out. This was for a basic annual checkup and oil change, but it looks like they'll have more work to do. The bad news is that at least one of the accounts I read said, "engine out" required to repair coolant leak. I suppose I'll have to bite the bullet and get it done, but I can add a few things to the list (valve cover gasket replacement, Wagner intercooler install, new headlight assemblies from Spitfire install, etc.). So, maybe not the worst timing.

Anyway, if anyone has any thoughts on causation, I'd be happy to hear them. The Indy is ~50min away (mostly highway driving), but I'm not sure I want to take a chance. I could top the reservoir off and hope for the best, but why overheat and lunch the motor. I suppose I'd have warning bells coming on before it blew up, but it's no better to be stranded on the side of a major highway waiting for a flatbed. My inclination is to have it transported, but if anyone has any thoughts on it, please feel free.

I suppose this seals the deal for me, though. I test drove a CPO'd 2021 Avant and made an offer. That car sold, but it would seem to be time to fix the '03 and get into the '21/'22. Or, maybe wait for a Performance to start coming off lease. That extra 30bhp will be really useful in stop and go traffic...

CW

[hahnmgh63]

Did you ever replace the cheap OEM small Coolant pipe between the Coolant to Oil exchanger with an Aluminum Bufkin pipe? If that is leaking it is an engine pull or at least an engine drop of almost 12" to get to it. I think the right engine mount has to be removed to get to it, been a while since I've looked into that area.

[hahnmgh63]

https://www.gruvenparts.com/4-2l-audi-vw-billet-oil-cooler-tube/
The plastic pipe just disintigrates after years of use, it's only about 2" long. There are of course the hoses that go to that cooler, and the Turbo on the right has an upper and lower cooling hose. But that Oil cooler pipe is one of the most common culprits.

[CornersWell]

Thank you. Very helpful. I'm not aware that it has been done. I certainly never specified that it was to be done at any point, but if it's a part of a service kit, possibly it was, and I wouldn't know it. But, importantly, even if it's not the cause of the leak, once they're in there, I'll have them do it, regardless.

CW

[strlgag]

I would agree with the previous poster - oil cooler pipe. I never had the engine out to do mine on the RS6 before I sold it, but I did replace it in my 2000 A6 when it went out on me at about 137K miles. Seems to be a common problem with the 4.2 V8 around 125K+ miles.

[CornersWell]

Thanks.

Part is ordered and on the way.

While the car is now 20 years old, I'm at only 80K. So, timed out, I suppose! Which is why I'll likely move to the new RS6 Avant after fixing this. There's just a LOT that could possibly also time out/go bad, and, while the RS6 isn't the daily driver, per se, I don't want it stranding us on the side of the road anytime/anywhere.

CW

[SteveKen]

My only other thought is that the leak could be one of the hoses to/from the aux radiator behind the intercooler.

[CornersWell]

Possibly, for sure. I had wanted to do the Venairs years ago, but couldn't find them at a reasonable price, and, then, I bought the Wagner Intercooler kit (which includes them) and have been waiting on that. In fact, I'm now thinking I may not do the Intercooler kit upgrade, buy the RS6 avant, sell the '03 and offer the Wagner kit back to the community. That said, until I have a diagnosis, I'm just loading up the car with new parts for the Indy to install!

Keep 'em coming, everyone.

Thank you,

CW

[CornersWell]

Car was transported to Indy. While I haven't seen any photos, yet, they've diagnosed it as a, "...steel braided line rubbing against an aluminum tube." To repair, they must put the car into service position. So, I approved, and front end comes off. While I'm in there, I'll have them look around and consider what else we might do.

Thanks, again, for all the suggestions.

CW

[SteveKen]

One of the oil cooler lines has abraded on of the aux radiators hard lines.

You can simply disconnect the aux radiators without putting in service position. You just have two block off two hoses.

[CornersWell]

Interesting. i will follow this up.

Thanks,

CW