What is this weird noise?


#1

My friend’s 2018 Nissan Murano is making a weird high pitched intermittent squeal noise. It kind of sounds like an old rusty swing or door blowing in the wind or a train breaking. It happens when the engine has been turned off for 3+ hours. No key in, nothing running, should be cold just sitting in the garage. The car is possessed.
It sounds like it’s coming from the back of the engine. The dealership cannot get the damn engine to make the noise probably because she normally drives over an hour one way to work so they probably are not running it long enough. This has been going on a few weeks and today her forward emergency braking light came on.


#2

If the dealership is unable or unwilling to do the necessary diagnostic work on this fully-warrantied vehicle, then the OP needs to contact Nissan’s corporate customer service staff. Contact info can be found in your Owner’s Manual.


#3

The dealership ran a diagnostic test and of course nothing came up. They are taking it in again today for the new light that just came on.


#4

The part of the brake system that is toward the rear of the engine compartment that could conceivably make a noise like that is the brake power booster. That part has a rubber diaphragm that could spring a leak and make a sound like a balloon very slowly deflating through a small hole. I have to say I’ve never experienced that myself, but it seems like it could happen. There’s a one-way check valve in that area that could be the culprit too. When the sound is occurring try isolating where it is coming from exactly using a length of old garden hose as a stethoscope.