Avantadrive_Original

2012 3.0 81k miles.

Car had developed a slow coolant leak. Took it to a reputable Indy shop 2 weeks ago. Diagnosed bad water pump and replaced it (also did VCG and engine mounts).

Car ran fine after that but wife was driving tonight and got a critical low coolant warning. Fortunately she was almost at our house so she was able to get back before it started running warm.

Quick Look in the bay and there’s coolant everywhere. Seems to be dripping from somewhere near the pump but I’m not really sure.

Just had it flat bedded back to the same shop.

What could be causing it? How ticked off at the shop should I be? Because I’m pretty dang annoyed to be dealing with this a week after they supposedly fixed the issue.

kronikfumes

I had a slight coolant leak post water pump service. Ended up being a leak in bleeder valve if I remember right. Indy shop that did the service was able to diagnose the leak and fixed it free of charge. I would just go in, tell them how it started after the service. And they should take care of it.

Audi Logic

When my pump failed I found that the pipe that goes into the thermostat housing was broken. It actually wasn't leaking which was strange, because the section with the oring was severed. The pipe was literally held in by friction and I'm sure if I hadn't caught it I would have had a major leak down the road.

Avantadrive_Original

so not sure if this is the same thing but the shop is telling me the heater core pipe under the supercharger is broken. They claim this to be completely unrelated to the original problem or repair (ie the water pump). Seems far fetched to me that the car had a coolant leak, they replaced the water pump and now it has a completely random unrelated coolant leak. What do you all think?

Quoting me $800+ because they have to remove the super charger and I guess the intake manifolds.

GDawgA4

It's not out of the question given the age of the car and could be an unfortunate coincidence. It sounds like they removed the SC to do the water pump. If they did, it's possible they could have unintentionally disturbed the pipe in the process. The coolant pipes are plastic and connections made with o rings. Over time they can harden/deteriorate so any slight disturbance can cause things to start leaking.

Avantadrive_Original

Thanks, I went and took a look at it at the shop this AM. I agree it’s too coincidental that they had all of that taken apart and then randomly the hose failed. More likely is what you said, the hose was already in rough shape and by moving it around and also pressure and vacuum testing the system, they hastened its demise. Regardless, they’re not going to be on the hook for it which I guess makes sense.

Going to have them fix it and also probably do the PCV and the thermostat while it’s apart again.

GDawgA4

Yeah, it's one of those risks as our cars get older and things get disturbed while doing repairs.

Good call on doing the PCV and thermostat while they're already in there. Those, if not having been replaced already, will need to be replaced at some point. Now you know you'll be good for a long while. I would suggest doing the coolant cross pipe too if that hasn't been done since it's right there and something else they have to touch. It's another point of potential leaks as it ages.

wjsong

Most likely the shop would not have removed the supercharger if they just replaced the water pump only? So, if the plastic pipe underneath the supercharger, that takes the coolant from the thermostat to heater core, is now broken, they are probably not related.

Yes, the coolant crossover pipe probably needs to be replaced sooner or later. I just did mine on 2021 A6. The plastic pipe was more expensive than the water pump! pho

Avantadrive_Original

I'll ask about the coolant crossover pipe too... is that relatively easy to get to if it leaks in the future? Why does this coolant system seem like it was made of tissue paper?

I went over the car with him today and he showed me some videos the tech took... I see what they're talking about. The pipe really isn't accessible with the supercharger on, and it wasn't removed previously as mentioned. No choice but to have them do the work at this point.

wjsong

I think you can change the crossover coolant without taking off the supercharger and intake. I just did this so trying to imagine it in my head, but I think you need to take off the two serpentine belts, and the water pump cover to get to the crossover main pipe. There are a few hoses/brackets (leading to supercharger intercooler crossover pipes) and plugs and brackets you need to also take off around it, so you can get to the 2 bolts on each side that is holding up the coolant crossover pipe.

But it will be a pain to try to do all of those later. While the supercharger is out this can be easily replaced.

Red circled item is the crossover pipe