jesseusmc

Okay guys I have a 2001 audi a8 4.2 now I did a full flush on my coolant system and also got all the air out of it. Now the car ran below the half mark on the temp gauge. So I thought all was good. We'll it started heating up and got over the half mark and my low coolant light came on I stopped let it cool down and checked the coolant and it was very very low. I saw no visible leaks. So I fIlled it back up and it ran under half mark and then it did the same thing. I see no leaks on the ground other than the ac drain tube. Now here's the thing I noticed a puddle of liquid on my passenger floorboard. I don't know what it is. Could this be my missing coolant?

twentysevenlitres

Smell it - coolant has a distinct sweet smell.
Also, get some white paper towelling and let some of the liquid absorb in. See if it's pink.
If you get an affirmative to both these 'tests', then you've got a leaking heater core.

There's two cores in an A8, left and right, so potentially you could bypass one. Access is from either side of the large fresh air inlet in the plenum area between the bottom of the windscreen and the firewall. It's very restricted though.
I'd have to take a look through Bentley, but I think the heater cores are removable from the plenum area, without having to take the dash out as in most cars. So potentially it's not that huge a job.

Make sure you check that water in the passenger foot well though, as if it's just water it could merely be a blocked drain!