JFNash

A couple days ago the engine wouldn't start. I thought it was a dead battery (installed 5 months ago), so I brought a mechanic with a new battery.

While the mechanic was working on replacing the battery, I heard some discrete noise coming out from under the hood and windshield area (driver's side). I didn't pay much attention.

Now, when I switch off the car, I can hear the noise (it's like the door's closer sound but with higher interval and it comes out about every 30 seconds). When I'm at complete stop, I hear the noise with the rpm dropping a tiny bit until the noise fades away when the rpm gets back to the normal level. The episode is repeated every 30 seconds or so. Today I felt the battery started to drain (it took longer to start the car).

What could be the problem?

LS460, '08, VSR fix done 1 year & 30K miles ago. Last service the tech found a minor leakage in the water pump but haven't fixed it yet. No other problems or symptoms.

Thanks.

adamls2

I hear that sound too but only once after I shut off the car. Ive always been curious to know what it is.... Hope someone can help you.

I8ABMR

I also get a weird mechanical/actuated sound that comes from the car after I turn it off. My GS would do the same thing. no clue what it is, but have been curious for years. Anyone have a clue???? In terms of the OPs issue I would simply take it in to a Lexus service drive and they will get things sorted for you

JFNash

It seems the sound is there with everybody (by design?). Did I just notice it? Or did it just start coming out?

The interesting this is that the sound stops coming out after some time after shutting off the car. I just can't believe the sound has been there and I just noticed it.

kitchamp

My old LS400 used to make the actuator/mechanical sliding sound about a minute after turning off the ignition. I asked an old Lexus mechanic, who told me that it was part of the HVAC system closing the air inlets after turning off, to prevent dust from entering the ducts and settling inside. Apparently the old system didn't use flaps to mix hot/cold air, but instead used something like photographic film with various sized slits cut in it to allow air to pass through at different flow rates, claiming it was quieter. He said that when the car turns off, the HVAC slides these strips of film into a closed position. I never questioned anyone else, but I know I hear the same type of sound when I shut of the ignition in the current car.

Not sure about the OP's repetition of the sound, mine only does it once and stops.

CJITTY

Mine does too and I believe it is HVAC related. Turn the car off..open the door and then close it...then wait a few and it sounds like the vents are closing behind the dash

edarte

I read somewhere that this might be due to the brake system releasing pressure after shutdown which would be normal.

InRBigness

on the RX there is a noise that is related to the purging of the fuel system pressure. When I first heard it I thought I had ghosts in the machinery.

Craig B

That's the same noise I have on my LS 460 and GX 460. It's purging the fuel system pressure and that's what the shop foreman told me at my Lexus dealer. It shouldn't be draining your battery.

JFNash

Okay I just found out where the noise was coming from and what was causing it.

First off let me clarify one thing, I noticed that when I shift the gear to D and am at a complete stop, every ~5sec the RPM gauge would drop from 650 to ~550 and get back up again. It would go into an infinite cycle as long as I'm on D or R.

I took out the air filters and used an air blower to clean off the dust. The problem almost disappeared (both frequency and intensity). So it would take almost ~10sec to appear and the RPM would drop only slightly.

So I replaced the air filters and, Ta-daa! The problem is gone!

So yeah it was the dirty filters, although I replaced them last October and cleaned them last January but we have been getting dust storms on a daily basis for the last few months so probably I need to replace the filters more often.

As to the battery, after multiple tests it turned out to be perfectly fine and I was probably just mixed up.

Just for the records and future reference I wanted to share the results with you guys, hoping you don't need to visit this thread in the future.