Strange noises from 2004 Jetta

[NickC]

We just got a 2004 Jetta GLS (1.8 Turbo). I've noticed a couple of strange noises from the car - these are all with the engine OFF. If anyone could give some insight that would be great!

1. When the driver's door is opened, there is a 2 second motor hum from somewhere in the rear. This is not when it's first unlocked. It happens for example when the car has been sitting unlocked for some time in the garage. You open the door and you hear this motor hum. Then for the next few minutes (haven't timed it), you don't hear that motor. But after sitting a while, it does it again.

2. The other day I wanted to wash it. Rather than turn the engine on only to back it out, I just shifted into neutral and let it roll back from garage to driveway. Naturally, I had to turn the key to release the shifter so I could shift into neutral. When I got out, I noticed a noise from the front (I think right) side of the car - sounded like a pump. But I hadn't started the engine yet - what could that be?

[jettaboy]

That hum is the car being primed I believe, my 2000 does that.

[NickC]

Thanks. Primed in what way? Is the pumpnoise from a water pump or fuel pump?

And what about when the door is opened?

[surferfletch]

Fuel. Builds pressure in the line prior to start.

[jettaboy]

I not sure but, I think it only sets off the fuel pump, when driver side door is opened, This I know, because when my fuel line broke, when I opened my door, fuel sprayed everywhere!

[NickC]

Cool - thanks for clearing that up!

Man, that image of fuel spraying when you opened the door doesn't sound pleasant!

[NickC]

I tried to listen carefully again, and the noise from opening the door is distinctly different then when I just turned the key so I could manually roll the car out of the garage. When I turned the key (but didn't start the car) for a minute, I heard a pump noise from what seemed like the front right side of the car. And it stayed on for a while.

But when I open the door, it sounds more like a motor running somewhere near the back. I hear the motor start and about 2 seconds later it stops. Is that also the fuel pump?

[surferfletch]

That sounds like the motor for the power locks. Mine runs for about 10 seconds on rainy days. A vacuum leak can cause it to stay on longer. It comes from the driver's side of the trunk.

[NickC]

I kinda thought the same thing. My family had this 1977 Mercedes which had locks that moved like they were on a motor. Instead of popping up (or down) immediately, they'd slowly lift or lower as the motor turned. And it made a sound like what I'm hearing.

But then if the car is already unlocked, why would the motor run??