Help Diagnosing a high-pitch noise? (LX450) (1 Viewer)

[LandCruiseCzar]

Hey Guys - Just got this awesome LX450 back from Slee (pic below for fun). But would be exceptionally grateful for your help diagnosing a noise.

Driving it home the first time, everything's great, except there's a very, very faint high-pitched noise:
- comes on at higher RPM (above >3)
- can hear it while accelerating, car downshifts --> RPM up and the noise come on
- It's really faint, almost thought I was being crazy, but my girlfriend heard it too. Almost like a supercharger, but 1/100th as loud
- Sounds like its coming from behind me when driving
- Again, only when really hitting the throttle, RPM >3

Any ideas what it could be?

For reference, Slee just did couple things -- including front axle service, all the fluids (including transmission fluid), replaced all the hoses, throttle cable, and replaced the rear main-seal (which required them to pull the transmission).

Thanks guys,
- Spence

 

[LongDuck]

Completely normal - most refer to it as the Exhaust Whistle, and only really comes on under power when the 2 diverter from the manifold hit a resonant frequency. It's part of the fun of driving an 80, if you ask me,

 

[LandCruiseCzar]

Thanks @LongDuck - that's helpful (and an optimistic perspective re: "part of the fun of driving an 80")!

Do you know if there are any videos of the Exhaust Whistle? I'd love to take a listen to see if it's the same kind of thing.

My only concern is for years I drove my dad's old '94 FZJ80, and it didn't have this sound. Is the resonant frequency at a specific RPM? or would it simply be anything over a certain RPM. Thanks again. Appreciate the community coming through so fast with sage wisdom!

- Spence

 

[scottryana]

Yep certainly sounds like the exhaust whistle. Was your father's exhaust stock? You lose the resonator and you lose the whistle but the exhaust is a touch louder.

Exhaust makes a whistling sound at higher RPM, is that normal?

I had to drive with the upper rear hatch open about 4" (box sticking out the back slightly) and heard an exhaust whistle (or high pitch vibration) when accellerating at higher RPM. No sound at lower RPM or when cruising. Is this common with a stock exhaust ('96 FZJ80)?

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[Azca]

First of all, nice ride! That is a clean rig, enjoy!

I have not heard an exhaust whistle on mine but, I do get a high pitched hum, like an electronic hum, from my underdrive gears. You did not mention that the vehicle has them so stick with the exhaust as the gents have mentioned above. I did notice a whistle after I cut off my resonator for my labs bumper, had it welded back on and it is gone...

 

[bencallaway]

I had a crazy loud whistle that got louder when I cut my resonator off. It’s finally gone after I replaced my entire exhaust system. Probably clogged cats

 

[bhsdriller]

I didn't have it before but when I cut the resonator off for the 4x4 labs bumper I do now. Just got used to it don't even really notice anymore

Turn the radio up louder

 

[LINUS]

I’ve been watching the “twin” of your 450:

No Reserve: Modified 1997 Lexus LX450

Bid for the chance to own a No Reserve: Modified 1997 Lexus LX450 at auction with Bring a Trailer, the home of the best vintage and classic cars online. Lot #43,976.

bringatrailer.com

-I’m just curious what a 65K 450 brings now.

 

[LandCruiseCzar]

I’ve been watching the “twin” of your 450:

No Reserve: Modified 1997 Lexus LX450

Bid for the chance to own a No Reserve: Modified 1997 Lexus LX450 at auction with Bring a Trailer, the home of the best vintage and classic cars online. Lot #43,976.

bringatrailer.com

-I’m just curious what a 65K 450 brings now.

Amazing find @LINUS - wow that's really the twin. (although 1/2 the miles)

 

[vegasfj40]

Mine does the same thing. Only under load on the freeway. Wonder if it's from the y pipe? The crotch of the Y seems to get a very small leak on some 80s.

 

[brockdeck]

I had a crazy loud whistle that got louder when I cut my resonator off. It’s finally gone after I replaced my entire exhaust system. Probably clogged cats

My understanding was that this problem on 80s is caused 90% of the time by damaged chambers in the muffler. When I replaced my muffler it went away.

 

[LINUS]

My understanding was that this problem on 80s is caused 90% of the time by damaged chambers in the muffler. When I replaced my muffler it went away.

- alot of us recall it just being the sound of a OBD2 setup, but you can say what you want.

I sawed off my resonator for my Hanna Quality bumper - no more S/C ‘faint whine’ - but that was so long ago I can’t say what president was in office, let alone a specific year.

 

[LandCruiseCzar]

Thanks for the thoughts guys! Appreciate the advice and wisdom.

Small New Piece of Info:
Went into the garage, revved the engine while in park, and did not hear the sound.

So the noise is only when under load (like accelerating on the highway) with RPM over 3. Does that give you guys any additional clues? If it were standard exhaust whistle, wouldn't I still hear it even if parked?

For reference, read through the posts above -- seems like most people either noticed a whistle louder than mine or they still were able to reproduce it even when parked and not in gear.

Gratefully yours,
- Spence

 

[FMC80]

Hey Spence,
Did you notice the 6-9 threads @scottryana put up and others answers to your question? Obviously you have which makes me think this noise is somehow different on your ride. Otherwise, this is a very common occurrence based on me perusing those threads he posted. Mine also whistles under acceleration and goes away in when I shift into park regardless of RPM. It’s only in drive and under load. When I’m on the highway cruising, it isn’t audible unless I get on it. I like the noise, I don’t want to lose it. Just as well, my truck identifies itself as a 3X locked, OBDII, lifted and turboed LC on 40s, so the noise stays.
Don’t throw money at it.
Pell

 

[LandCruiseCzar]

Hey Spence,
Did you notice the 6-9 threads @scottryana put up and others answers to your question? Obviously you have which makes me think this noise is somehow different on your ride. Otherwise, this is a very common occurrence based on me perusing those threads he posted. Mine also whistles under acceleration and goes away in when I shift into park regardless of RPM. It’s only in drive and under load. When I’m on the highway cruising, it isn’t audible unless I get on it. I like the noise, I don’t want to lose it. Just as well, my truck identifies itself as a 3X locked, OBDII, lifted and turboed LC on 40s, so the noise stays.
Don’t throw money at it.
Pell

Sounds amazing @FMC80 - what turbo do you have installed?

 

[bencallaway]

Thanks for the thoughts guys! Appreciate the advice and wisdom.

Small New Piece of Info:
Went into the garage, revved the engine while in park, and did not hear the sound.

So the noise is only when under load (like accelerating on the highway) with RPM over 3. Does that give you guys any additional clues? If it were standard exhaust whistle, wouldn't I still hear it even if parked?

For reference, read through the posts above -- seems like most people either noticed a whistle louder than mine or they still were able to reproduce it even when parked and not in gear.

Gratefully yours,
- Spence

My exhaust whistle was only while driving/ under load/ not in park.

 

[FMC80]

Sounds amazing @FMC80 - what turbo do you have installed?

Key words in my post is “it identifies”...my poor attempt at humor

 

[60wag]

Mine whistled without the resonator, so I put it back on. No more whistle.

 

[fresnoLC]

I didn't have it before but when I cut the resonator off for the 4x4 labs bumper I do now. Just got used to it don't even really notice anymore

Turn the radio up louder

I thought I had a pulley going, or something wearing out, mine seems like more of a whine than a whistle but it matches all the other conditions in the thread. Guess it was removing the resonator that did it. Didn't see that asterisk on the Labs bumper page lol

 

[LandCruiseCzar]

Quick update:

Brought the LX back to Slee... and..... dun dun dun dun...

It's exhaust whistle.

Thanks guys - y'all were right, but still glad I double checked in person. Best,
- Spence