2000 A6 2.7T 6spd

I am losing coolant gradually, and from time to time, you can smell coolant when the car is up to temp. i do not have a problem with overheating. i do not see evidence of coolant in the exhaust, oil, nor does it leave puddles when parked. so i previously stated, i drive hard, and the car has 137000+ miles on it. the timing belt and waterpump were done by a family member of the previous owner, who is an audi tech. i don't know at what mileage. i do know the k03's were replaced with oem k03's at 120k'ish. i bought it with 125k'ish.

here are my symptoms. the car doesn't have the power it did. it doesn't seem to be dying off, as there has been no degredation in power over the last 5-7 thousand miles. part of me thinks i have become accustomed to the car and it doesn't feel as extreme as when i bought it. but occasionally under hard boost, i'll get a surging. i don't have a boost gauge so i don't know if the boost is surging, but that's what it feels like. i have examined the tbb, and it doesn't appear to be torn. but i can't help but feel like i'm losing boost.

this might be related to the loss of power, but the car has picked up what sounds like a valve rattle or the sound i'd expect from a deisel engine. it goes away for a short period of time after you change the oil, but for the most part it will rattle once it has warmed up. I seem to remember reading somewhere that this rattle is the hydraulic cam chain tensioners. I have also read about that sound being caused by a secondary air valve of some sort? occasionally it will idle roughly when it's warm as well.

so, do you guys think i have a blown head gasket? and if i do, what are some of the other items that should be replaced along the way? the coolant, the surge and the rattle combined have me a little stumped. i'm not an ASE tech, but i am very familiar with auto repair.

 

Check your coolant resevoir for cracks. Open the cap after a few hours and see if hear an air rush.
Check your hoses for coolant residue if it leaks slowly you won't have a puddle but white or pinkish residue where it's leaking from.
check the crossover pipes.
Do a compression test on each cylinder.

 

I have the same problem on the same car. Except no noticable performance issues. Just gradually loses coolant. No smell. No drip. No water in oil. Hmmm.

 

One of the places that these cars (2.7t) are known to leak coolant is at the aux water pump. It is an electrically driven pump that is mounted UNDER the intake manifold. A PITA to get to. With a small leak, the pink coolant used in Audi's will turn to a crusty powder, and NOT drip on the ground.

Is there a procedure to pressure check an Audi's coolant system? (I have seen such for American iron.)

OBTW: I have seen a kit to pressure check the air intake system. Might be an idea if you find your boost is low.

 

Ditto on the aux cooling pump. I experienced the same fluid loss and we found the dried coolant all over the transmission housing.

Yes - you can get used to the power, even when chipped, after a while. Not sure what you mean by surging.....does it surge under steady throttle or when accelerating hard? If the latter, my guess is that your clutch is starting to slip. When it happened to me, it felt like the car would surge forward when the clutch grabbed. It typically slipped under medium-heavy acceleration, e.g., when merging into freeway traffic. Eventually it degraded to the engine revving towards the red line with no corresponding power. BTW, I've got 144k on mine with stock everything except what's noted below (and a replacement alternator at 75k).