Buzzing sound after start-up

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Bighead

Bighead

Veteran of the Psychic Wars
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I am getting an unusual sound from the engine after starting my LC. The engine starts normally but about 3-4 seconds after I release the key, there is a buzzing sound that comes from the engine that lasts ~1-2 seconds. The engine does not stutter or die, just that sound and then everything is fine. Also, this has only happened after the first start of the day. Any ideas...starter issue?

Thanks for the help.
 
Hmm... I always thought that was normal. Perhaps attributed to the ABS or something spooling up or repressurizing. But looking at your Join date, you ain't no spring chicken. As a matter of fact, I would be the newbie!

Anyhow, for what it's worth: I was reading through the LX470's owners manual a while ago, and noticed that the text kept referring to buzzing or whirring noises during the first seconds of startup, usually in conjunction with the VSC, ABS, or A-TRAC lights lit. The manual says not to worry if it goes away in a few seconds. If the warning lights stay lit, take it to your Lexus dealer, etc.

At the risk of asking dumb questions: Did you begin to notice these noises only recently, or could they have been there for some time now? Do they sound serious/ominous, or are they just (as you mentioned) unusual?
 
I just bought the LC a few months ago. My wife drives it more than I do and she was the first to notice it. The thing that gets me is that it only happens after the first start in the morning...other than that it is fine after it cranks.
 
Are you sure it's not the master cylinder pump? If you turn the key "on" (but not the engine on), you'll hear the master pump run for maybe 20 sec to build up pressure in the brake system.
 
I have noticed the same thing this past week or so since its been cold around here. It is coming from the brake cylinder area. Havent noticed anything else out of the ordinary though...
 
I owned a 93 4Runner before the LX. No whirring noise from the master cylinder. I guess it was a simpler machine.
Either that or my brake system wasn't working.:D
 
Jim_Chow said:
Are you sure it's not the master cylinder pump? If you turn the key "on" (but not the engine on), you'll hear the master pump run for maybe 20 sec to build up pressure in the brake system.
Click to expand...

I know the sound you are talking about but this sounds nothing like my 4Runner's does. If it is the master cylinder then it sounds like it is about to die. This is a loud buzzing sound that will last from 2-5 seconds. It almost sounds like a joy-buzzer if anybody remembers those. I initially thought the starter was stuck the first time I heard it.

SWUtah said:
fuel pump?
Click to expand...

I've never heard a bad fuel pump before. It sounds like it's coming from the passenger side of the engine bay.

Thanks for the help guys...this is bugging the hell out of me.
 
Bighead said:
I know the sound you are talking about but this sounds nothing like my 4Runner's does. If it is the master cylinder then it sounds like it is about to die. This is a loud buzzing sound that will last from 2-5 seconds. It almost sounds like a joy-buzzer if anybody remembers those. I initially thought the starter was stuck the first time I heard it.



I've never heard a bad fuel pump before. It sounds like it's coming from the passenger side of the engine bay.

Thanks for the help guys...this is bugging the hell out of me.
Click to expand...

Reason I mentioned fuel pump was on my FZJ80 you could hear the fuel pump presurize, kind of sounded like a buzzing, first thing in the morning, never noticed latter in the day. My LX is way to insulated to hear thinks like that.
 
calbo said:
I owned a 93 4Runner before the LX. No whirring noise from the master cylinder. I guess it was a simpler machine.
Either that or my brake system wasn't working.:D
Click to expand...

4runner didn't go to the electronic brake booster until '03. Before that, it was good old-fashioned engine vacuum pressure, no ABS.

Getting back on-topic, the master shouldn't make a loud, buzzing sound like you describe. It's more of an electronic servo sound that can only be heard w/ ignition on and engine off.
 
I had a 01 4runner limited and it had ABS. Could hear that pump regularly coming on and make a quite audible buzzing sound behind the fire wall. Pumping the brake while stopped would predictably make it come on.
 
Getting back on topic, my wife keeps asking me what those wirring sounds are coming out of the LX engine area every once in a while. I have not even noticed those yet. But no buzzing after startup that I can hear.
 
Joy buzzer, eh? Just an idea, but is it the same sound that comes out when you shut the engine and open the driver's door while the headlights are on? Ehh, that's a long shot.

Perhaps it would be a good idea to pop the hood, ask your wife to start the engine, and listen for that sound. Try to identify if it's coming from the master cyl or somewhere else.
 
For sure it's the brake booster pump.

To check positively:
1 Stop the engine
2 Turn ignition on
3 Pump the brakes full stroke a few times (less than 10)
Then the pump will start, to get the pressure up again.
It's quite audible from the driver's seat.

Try it, just to get to know your vehicle.
 
uHu said:
For sure it's the brake booster pump.

To check positively:
1 Stop the engine
2 Turn ignition on
3 Pump the brakes full stroke a few times (less than 10)
Then the pump will start, to get the pressure up again.
It's quite audible from the driver's seat.

Try it, just to get to know your vehicle.
Click to expand...
I'll take a look at it when I get home...Thanks.
 
Depends on how the buzz is. The booster pump is audible, but when driving you can't hear it over all the other sound. I hear it when idling, but not while driving. I can also just about feel a slight vibration in the brake pedal when the booster is running. It looks like the pump motor gets more noisy by age, like, a worn motor has a louder noise.

Anyhow, the buzzing is from the booster, not from the master. Although it is directly connected to the master, and the dealers do like to change both as one unit.
 
Is it a metallic sheet metal type noise that seems to come from underneath the vehicle? I noticed a slight buzzing sound on my 99 LC that only lasted for a short time, and only occurred upon cold startups. I found that the heat shields on the lower catalytic converters had cracked around the mounting nuts. I installed a larger washer underneath the nuts to pinch down the shields and it took care of the problem. Worth a shot...
 
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