Hey guys,

My wife noticed a noise in the Xterra after it was shut off and the key was out. I left her in the truck when I ran in to a store for something quick.

I didn't believe her, until she insisted I sit in the garage until it happened. We had to sit in the Xterra for around 5 minutes after the truck was turned off. I almost left, but I did hear it.

It sounded like a pump unloading under the hood. My guess is the windshield wiper lines are pressurized or pre-pumped because when I hit the sprayer for the rear window, I get liquid right away. My old 2001 Xterra would take a while to pump the liquid to the back window.

Has anyone else heard this noise? Is my guess correct?

Thanks,

I have heard the noise, but I sometimes hear voices too...

I like your explaination. No idea if it is right but I also noticed immediate water on the rear window unlike my 01

I heard the noise once. But I don't know what it is.
Also, after I shut down the engine for 3-5 mins, my speed gauge and RPM gauge will drop to below 0 and return to 0 in a second (looks like some kind of reset)

haven't heard it.. but bear in mind that modern cars still use vacuum for a couple of tasks.

might have been the hvac vac tank purging (assuming the heater contols aren't all elctric).

bear in mind the fuel tank vapor recovery has a self testing pump that pressurizes the tank and vent system to 1 psi as a self check to make sure it doesn't leak. there is a small pump for this- it is part of the emissions system. recall all the check engine lights for lost or removed gas caps before they made the filler tube sealable?

maybe you have a mouse?

just thinking out loud.

What kind of noise is it? I've noticed that the vents reset/close when I turn off my X. Just a light hissing/whirring noise. Just my 2 cents...

Is this the same noise that you hear when the key is turned to the on position with the engine not running? I have noticed the sound of vacuums or something else, if you turn the key back one it turns it off.

I am sure you are talking about something else since your key was removed but try this out and let us know. If you are working under the X in a quite place you will hear something churning.

My 300zx used to have a buzzing sound when you turned it off occasionally. It was caused by the fuel pump. I haven't heard anything from my X, so that's my best guess.

I have the same noise almost like the fuel pump priming, except the truck is shut off. The noise is really simialr to the fuel pump noise on my 98 Chev 3/4ton, which by the way has to be the loudest fuel pump on earth.

Pressure in the gas tank? Try removing the gas cap next time you hear it, does it stop then? That is with the ingnition turned off.

HVAC system. The air diverter "rests" in a given alignment which it returns to.

This makes sense to me.

just thought i'd bump this up now that i'm experiencing something strange.

The problem isn't the noise itself (I know what it is, where it comes from, and why it happens). My problem is that when the air-diverter 'repositions' itself, it starts to go haywire. It's almost as if someone was playing with a switch moving it back and forth. Most of the time it'll stop on it's own. Other times it won't, and the only way to stop it is to turn the ignition and start up the fans, then turn off. What sucks is that I can't duplicate the problem to show the dealer. I also notice it more frequently now that the winter weather is coming.

any ideas on what it could be?