Mysterious Coolant Loss on A4 2.4 Se

[abcon1]

Wondered if anyone had an idea where coolant is going!

My car has done 180,000 miles now and still running fine, however over past few years had to top up coolant every 3 -4 months (4-6,000 miles).

But in past few months it's quickly gone down to every 200-300 miles or so and getting irritating. I put leak dye in and used UV lamp under engine on ramp and above and no signs of where leak is.

Then I used co2 gas checker to test if any coming through engine into expansion tank, but no co2 present. Does anyone have an idea where it's going and how I can test?

[cookie1979]

check the passenger footwell.

[abcon1]

no signs of leakage coming into car, just can't understand where the coolant is going!

[LozW]

I'm not a mechanic so this might be completely wrong. My brother had a coolant loss problem. It turned out to be a cracked cylinder head. Basically, coolant was seeping into the cylinder and would steam out through the exhaust. A blown head gasket could do the same thing (I think). The giveaway was that (particularly noticeably on cold days), a lot of steam would come out of the exhaust on starting up - but it would quickly clear and the car then ran fine. I hope it's not that though, neither is a cheap repair!