Nice Ride

I posted this thread earlier and I thought some who responded would like to know the mystery is solved. I talked with Service Advisor at local Chevy dealer that sells a lot of Corvettes about the fluid/circulating noise I hear for a few moments at cold start up. He said the evaporator core pressurizes at start up and circulates freon through lines located behind the dash. The sound of circulating fluid can be audible initially while system pressurizes. System pressurizes automatically at start up as part of normal functioning independent of driver settings. Thanks!

f152tall

Gurgle, knock, clicking?

bmxbaddy

Is this a running water sound you're talking about? I always wondered about it and have meant ask for a while now!

Vetteman Jack

Thanks for the update.

Black&White

I hear no such sound.

Rooster OG

Nice follow through, thanks.

Z06 1of38

Z51?

Dry sump oil system.

WelderGuy

" He said the evaporator core pressurizes at start up..."

That's incorrect. The pressure in the evaporator actually drops because it's on the "low" side of the system.

The only noises I've heard from an auto AC system are the click of the clutch and the slight hissing as the pressure in the system equalizes when I turn the engine off on a hot day.

I don't think the noise you're hearing has anything to do with the AC. If it did, you'd hear the same sounds on every start, not just a cold start.

mksz51

No freon either - refrigerant but not freon.

You know how you make BS sound like fact? You just say it with authority.............

AORoads

Agree w. above mksz. The sound you may be hearing is more toward coolant circulating through heater core, but if that's the case something else is going on because imo, you shouldn't be hearing that at all. Which is what the second poster in your other thread, Bob Guzzy said, too. And I would also say, yes, with a/c and fan off, there are fluids circulating but it should be almost inaudible.

Z06 1of38

From a GM Bulletin

The Z51 Performance Package has a high performance dry sump lubrication system. This system operates differently than a standard engine lubrication system. Check the oil level only after the engine has been thoroughly warmed up and then check after a minimum of 5 minutes but no more than 15 minutes of engine shutoff. This ensures that the oil level reading obtained will be accurate.

Some customers may comment on a noise similar to running water that can be heard from the dry sump oil tank area when the engine is cold and started. This is a normal sound caused by the oil returning to the tank.

You would almost swear is was water rushing in the glove box or upper air bag area.

AORoads

May like to publish that bulletin number so OP can go in and show it to his Service Advisor esp. since his car is (from the other thread) "2015 C7 3LT Z51 A8." Guess it's not coolant but oil!

kevincol

I hear it every morning I start the car.