slicksic

Hey guys, a little help would be really appreciated here.
Started losing coolant a little while ago, sometimes up to about a half gallon in less than a day of driving. No leaks anywhere whatsoever, checked and rechecked. Don't think I'm burning either but didn't rule it out, just the worst case scenario.
Here's the weird part: I can lose 3/4 of the reservoir tank in a few hours of driving (and sometimes may take a few weeks), but once the coolant low light comes on, I can drive it like that forever and It seems I don't lose another drop of coolant. No coolant smell from exhaust, no leaking from heater core overflow (undercar transmission tunnel). Pressurized system to about 15 PSI, no leaks. What could be the problem? Coolant reservoir has internal leak? Intake manifold was replaced not long before this problem started, maybe the system wasn't bled properly? Would this cause the loss of coolant? Thanks in advance guys

chuckee98

Check your coolant reservoir. Mine suffered from stress cracks.

Some additional info:

http://www.audizine.com/forum/showth...lant+reservoir

bdubs

I'd bet on the coolant reservoir too. Mine went at about 55k miles. Total cost to fix was around $160.

daredevil1

The coolant reservoir costs $32.55 at genuineaudiparts.com
It's held on by 1 screw (at least on the A6) that you can do yourself. Think you got ripped off.

2008A6

I had similar symptoms..pressure test was fine, so they simply replaced the cap on the coolant reservoir as a precaution and it seems to be better now.
Not 100% sure if that was the issue.

bdubs

I had the dealer do the repair as I didn't know what was the issue at the time. Plus, I have an extended warranty so it only cost me $100 out of pocket. Given I didn't know what the issue was and didn't have to spend any of my own time figuring out what was wrong or replacing the part, $100 was a pretty good deal I'd say.

The part cost $60 through Audi, so they definitely have some nice margins.

hsp

Had same issue and fixed via new coolant reservoir. Starts developing hairline fractures at around 50k miles. I would not drive vehicle until fixed. Taking huge risk with expensive engine.

slicksic

Thanks for all the replies guys. Will try swappping out reservoirs.

2008A6

Did that fix the problem? I'm noticing slow coolant loss in my reservoir on the S6. Reservoir has been changed before, as well as the cap. No fluid or smell anywhere. It pressure-tested OK last time i complained about this during last oil change and they said everything's fine.. Coolant now is about an inch below MIN level mark. That can't be normal.
Any other ideas?

slicksic

Have not done anything to the car yet, it has been parked for a while due to this and other trans problems. please do let me know if you ever figure it out, it would be a great help. if i get around to figuring it out before you, i will make sure to let you know as well.