5

I just noticed a rattle/humming sound when starting my 2015 Toyota Highlander. It happened 3 times, all in the last week or so. It could be cold-related (around freezing temps). It sounds like some electric motor, similar to what a large computer fan would do. From the cabin, it was clearly louder than the rest of the car engine. Car heating and fan was off.

I immediately parked, and it continued for about 5 seconds, when I stopped the car, after cutting the engine. So, I ruled out:

  • rattling object in the car
  • heating/fan

I assume there is some pump or other component that could produce this sound. Pump that maintain oil pressure, maybe ?

I'm wondering what those components could be ? How critical could such a sound be, e.g. how urgently should I go back to the mechanic/dealership ? There are no check-engine lights or anything else indicating a problem.

Edit: regular V6 engine, not hybrid or anything.

Jeffrey
  • 193
  • 8

2 Answers2

1

This is apparently a normal sound. The vacuum pump, according to Toyota, can run at any time. It is required for emission control. And, depending on various conditions, can be much louder or quieter.

My understanding is that this pump is a part of secondary air injection. The injected air location varies with the engine temperature, according to the link above. So, outside temperature could affect operation (and noise).

Jeffrey
  • 193
  • 8
-4

Take it to the dealership ASAP. Not the kind of noise you want to ignore or even try to diagnose on here. Leave it overnight for them to check on cold-start and cold temperature.

race fever
  • 3,353
  • 13
  • 23