Qx4 starting and humming sound

[JPK Omaha]

I have a 2003 Qx4 with 99k miles. I have 2 questions, 1) usually the engine spins normally when I turn the key and starts right away. However a couple times a week the engine will turn real slowly a couple times, then it starts. I took it to the dealer and they say the battery and everything checks out fine. Any ideas? 2) Every so often when I shut off the engine, there is a mystery humming sound coming from somewhere, it sounds like maybe from towards the rear of the car but I can't pinpoint it. If I slam the door it will stop for a couple seconds then start humming again. When I go back 30 minutes later it has stopped humming - Any ideas? I don't think the two issues are related, they both seem to occur randomly. Thanks

[fueler]

The faint humming sound is normal, all R50's do it. Mine does it. It is a faint noise but you can hear it in a quiet garage. Never figured out what it was, though.


Slow starter is the sign of a weak battery.

[Towncivilian]

Open the hood and see if the ABS pump is constantly on, if so it will be making some whining noise constantly. If it's not that, try to pinpoint the location as best you can, perhaps park in a garage to help isolate the noise somewhat.

As for the starting issue, ensure both ends of both battery terminals are tight and free of corrosion. Just don't overtorque them to some crazy amount otherwise you'll crack the terminal and acid will leak, causing significant corrosion.

EDIT: I don't think my Pathfinder makes any sort of noise when it's off, but I almost always park outside so I probably never noticed it.