My car has recently started making a groaning noise, but only when it's cold. If I step on the gas pedal, the groaning gets much loader. Once the car warms up (not necesarily completely warm, actually just enough for the coolant gauge to begin to move) the groaning stops. I have no clue what this could be.

Any ideas? Thanks!

The Groaning you speak of I also have with C70 and have not defined it yet however
I have eliminated some things.
Acc Belt Removed same groan, Timing cover remove bearings/water pump seem ok.
Very hard to define location of the noise still investigating.
Thoughts are Oil Pump,Trans or Main Bearing (least likely) possiable serious problem.

Any other ideas out there?

Thanks!

I had the exact same problem. My mechanic discovered it was the serpentine belt tensioner. After replacing the tensioner, things are nice and quiet under the hood now on a cold winter morning.

Sounds like the air pump. It runs for a couple of minutes when the car is cold. It will need to be replaced.

http://www.volvospeed.com/Repair/airpump1.htm

Sounds like me in the morning, before my first cup of coffee :)
--
98 V70Rawd(101Kmi), 95 854T(85K mi), 75 164E(173K mi)

thank you, i'll check that out

Mine always does that when its really cold too. It does it every winter. My guess is it has something to do with the power steering, as if I move the steering wheel the noise gets louder. I don't think anything is wrong, its just cold. The noise always goes away after a few mins. Unless your getting check engine light codes, I wouldn't worry about it.

Its been in the single digits and teens here in Chgo lately.

Oak