Makiavelo7

Hi All,
Lately my 2004 GX470 has this strange like metallic noise behind the dash, it only happens when the engine is cold and I start it first thing in the morning. The after a few seconds it goes away. I have the idea that is related to the breaks system since I can feel the breaks pedal vibrating when the noise happens.

I've recorded it in video with the hope that any of you might be familiar with this issue...

Any help will be much appreciated.

ALAN553

DiabloX22

Need more info! Does it do it when any accessories are on? I saw you turning the wheel, does it do it turning and not turning it? Fort on the brake and off? Try to list everything that you are ent doing and or what's on or off if it matters

Makiavelo7

Does it do it when any accessories are on? The noise goes off when I start the engine first thing in the morning, the only accessory that is on is the A/C
I saw you turning the wheel, does it do it turning and not turning it? The noise starts even if I am not turning the wheel.
Fort on the brake and off? I noticed that if I pump the breaks the noise seems to go away

chiph9

Get an assistant to listen with the hood up, back towards the firewall on the driver's side. There is a pump there (the "Brake Booster") on the brake manifold that supplies assistance to the brakes (because the brakes aren't vacuum assisted like on older cars) and it can go bad after a number of years.

If it sounds like this pump, don't delay getting it repaired. If it goes out totally you will have to press VERY hard on the brakes to come to a stop, and your stopping distances will be MUCH longer (if you even stop at all). It's an expensive repair (~ $2000) but it's not something you can let slide AT ALL as it's a safety critical part.

Chip H.