2nd Gen Non-Engine/Transmission 02' Hissing Sound

[ike]

I recently bought a 2002 4X4 atomatic and when you shut the truck off there is a hissing sound like pressure being released from under the driverside battery. Has any one else experanced this problem or is this a normal pressure release from some system? Help please.



IKE



Bone stock,2002' long bead, 4X4, automatic

 

[JCyrbok]

my 01. 5 does the same, since new. I assume that it is normal as there has been no problems related.



Mine is kind of a pulsating hissing sound.



J-

 

[AKAMAC]

Check for a vacuum leak at the cruise control actuator.

 

[ike]

02'Hissing Sound

I Made a Mastake on my eairler post. This sound is comming from under the passanger side battery.



IKE

 

[AKAMAC]

What is the coolant level in the overflow canister? Is the noise after a long run?

Mike

 

[supersonic]

Ike, I can only guess where your from, but have you been using your A/C? After shut down, the pressure equalizes on both sides of the compressor an makes an air leaking/ hissing sound. Or you are just hearing the turbo slowing down, that makes a shuddering hissing sound.

 

[Cummins Thunder]

I agree with supersonic on the A/C pressure..... BTW, mine does the same thing.

 

[RDyson]

After I swiss cheesed the bottom of my airbox, I started hearing what sounded like a depressuring sound from under the hood. I thought it was the pressure that the turbo builds exiting back through the filter when I shut the truck down. It lasts for about 3-4 seconds after the engine stops. I dont have gauges yet, so I am not sure what pressure we have at idle. I would think that even 1# of pressure in the intercooler and intake piping has to go somewhere. Just a thought.

 

[ntillm01]

As folks have already said, the A/C is equalizing. The highpressure line is on the passenger side and contains an orifice in it. The pressure drop across the orifice is part of what make the R-134 cold. That hiss noise is there anytime the compressor is running, you just can't hear it until the engine is off. It's like spraying the lawn with an open hose and your thumb over the end to make the spray, then someone turns the faucet off. It takes a couple of seconds for the pressure to bleed down.

 

[ntillm01]

p. s... Mine does it too.

 

[RustyJC]

Mine does it, too. It's the A/C bleeding down (equalizing).



Rusty

 

[ike]

Thanks Guys,

I only experance this sound when running the A/C or defrost. I am gald this is normal. Thanks for all the replys.



IKE

 

[WestTN]

If you have been using either the A/C or the defrosters, it will be the pressure in the A/C systen equalizing.

 

[ntillm01]

Thanks Guys,

I only experance this sound when running the A/C or defrost. I am gald this is normal. Thanks for all the replys.



IKE

No problem, you're welcome.

 

[JeffWhite]

Check for a vacuum leak at the cruise control actuator.

does a 02 use vacuum for the cruise? my 02 does the same

I agree with the AC being what you are hearing