TheCat1

My LX470 recently started producing a strange electronic squeal sound like an eeeeeee! noise which is heard within the first minute of driving after the vehicle has sat overnight. I don't know what could be causing this strange electronic sound which is heard quite loudly both inside on outside the vehicle. The sound is like a long eeeeeeeeeeeeeee! sound lasting about two to three seconds before it stops and its not heard again until the vehicle sits overnight and is restarted the next morning and its only after the vehicle is driven for 30 to 60 seconds and then eeeeeeeeeeee!
Does anyone have any ideal what could be causing this (besides a family of mice living under my hood) and what the remedy would be so I can inform my Lexus dealer what to look for.
I appreciate your help.
Thanks,
TheCat1

1loudLX

AHC pump? Where does the sound...sound like its coming from?

TheCat1

The sound I believe is originating from the engine compartment and can be heard both inside the vehicle with the windows closed and outside the vehicle. The sound I hear can be best described and as an electronic squeal lasting approximately 21/2 to 3 seconds then disappears and is not heard again until the next day when I restart the vehicle after it sits overnite. I will not hear the sound upon immediately restarting the vehicle or if its parked for an hour or two, only when it sits overnite will I hear the sound again. Hope this help with suggestions to what might be causing this sound. I have spoken to the service managers at a couple Lexus dealers and no one has heard of such a sound or have they any idea what could be causing it.
I hope someone can help me.

Thanks, TheCat1

GS300-2002

Does your radio antenna still move up and down?

The engine on ours somehow disconnected from the antenna so at startup you hear the electronic motor running, sounds just like the sound you described, the car will also make the same noise if you push the antenna up or down button.

TheCat1

My Antenna is working fine without any noise, the noise I described has nothing to do with the antenna or radio.

TechLFA003

You got a cracked exhaust manifold. I've seen it so many times specially in cold weather. They crack right at the manifold pipe of the front #1 or #2 cylinder(depend on which bank). It take 1 second for it to heat up and expend to close the crack. You won't hear it again until engine is complete cold.

TechLFA003

I though about it some more. If you think your exhaust manifold is ok. Then it's your power brake booster pressurizing brake fluid for power brake. It's normal to hear it run in morning. Because overnight(6+hrs) it does bleed off some pressure. It run few seconds to recharge it's accumulator. All LX470 do do that.

TheCat1

The dealer checked the manifold and the accumulator and its not that so we have still not determined the source of the sound however, it has stopped as suddenly as it started six months ago. I now suspect that it could be temperature related as the sound has disappeared with the warmer weather. Not sure if the two are related but I'm at a loss to explain why the sound stopped after nearly six months of hearing it every day.