Weird sound when accelerating

[jokas]

TIA guys this forum has helped me tremendously.

Drove the car today. It is a '96 i30, 260k. Still drives like a champ. However noticed a swishing sound when accelerating. Doesn't seem like there is a loss of power, just an air leaking/swishing sound whenever i push down on the accelerator. If I let up, no more sound. Push down, sound. The sound was kind of like the sound of leaves rustling, when dragging a branch. No check engine light, no other indicators anything is wrong except the sound. Any ides's of what's going on and if it's serious? I did check under the car to see if I was dragging a branch or something... didn't see anything.

[audtatious]

Does it only happen when moving or do you hear it when you rev the motor from a stop?

[jokas]

It only happens when I press on the accelerator. Not related to car movement. Exhaust issue maybe??

[MinisterofDOOM]

If you get air in your heater core it can cause a swishing/liquidy noise which becomes more pronounced as throttle increases. To get rid of it you just need to bleed the coolant system by running the car with the radiator cap removed (make sure the radiator cap is the highest point of the car or you won't be able to get all the air pockets out--park angled uphill if you have to).

If it's not liquid-sounding it could be a vacuum leak.