Strange whistling sound from engine? (1 Viewer)

[ncduckman]

Good day all! Well, I am starting my third week of ownership of my new 1996 FZJ80. Last weekend I replaced the PHH and flushed the cooling system. This weekend I replaced the belts and alternator idler pulley. It is SO much quieter now. Next weekend will be new pads and pressure flush/bleed the brakes. Who knows when I will try to tackle the dreaded P0401!

So anyhow, I get this high pitched whistling/screeching sound coming from under the hood. It only happens at certain points in the throttle and does not seem to change pitch when the RPMs change. It reminds me of what a turbocharger sounds like. It appears to occur when I am getting it to the gas, meaning if I was accelerating and decided to give it a good dose of throttle, whistle. If I give it more gas, it will stop. If I let off a bit, it will stop. I can make it start and stop just by going through the range of motion of the throttle while under way. I have not checked to see if it does it when not under load or in park.

It almost sounds like a vacuum leak, but the truck runs great. It does not stumble or miss a beat when the noise occurs. I was hoping it would go away when the belts/pulley where replaced.

Any ideas?

Thanks,
Robert

 

[Blackdog]

Hey ncduckman, and welcome to the affliction that is MUD. My truck does the same thing with the whistle. I guess I just got used to it over time. I really don't notice it anymore. When I first got it, it was the first thing I noticed. I believe,at least with my rig, the whistle is coming from somewhere in the exhaust and not in the engine bay. It is really noticeable when accellerating on the interstate with no other distractions(ie kids, radio, wife). Kinda like a turbo whine. Prolly nuthin to worry about, but the MUD search is your best friend.

Blackdog

 

[ncduckman]

Thanks. I am all about the search, much to the chagrin of my boss, wife, kids, etc. That is why my new OEM wiper blades and belts went on this weekend.

I should probably clarify a bit. This whistle is not the typical WOT 3000+ rpm whistle. I have that too. This is something different and appears to almost be a function of throttle position rather than engine speed.

Robert

 

[VCCruzr]

Hey ncduckman, and welcome to the affliction that is MUD. My truck does the same thing with the whistle. I guess I just got used to it over time. I really don't notice it anymore. When I first got it, it was the first thing I noticed. I believe,at least with my rig, the whistle is coming from somewhere in the exhaust and not in the engine bay. It is really noticeable when accellerating on the interstate with no other distractions(ie kids, radio, wife). Kinda like a turbo whine. Prolly nuthin to worry about, but the MUD search is your best friend.

Blackdog

I have the same thing..."somewhere in the exhaust" and "Kinda like a turbo whine". But it runs very stong so I haven't worried about it much. I am interested in what others have to say about this???

 

[ncduckman]

I have the same thing..."somewhere in the exhaust" and "Kinda like a turbo whine". But it runs very stong so I haven't worried about it much. I am interested in what others have to say about this???

After more searching, I guess it is normal. Opinions vary on what is the cause, whether the resonator, collector, etc. Do a search on "whistle".

 

[Pinetop Cruiser]

All 3 '96s I've owned had the same sound under hard acceleration. Wish it weren't there, but sounds like it's just an 80 series thing. I wish I really did have a turbo whine.

 

[ba450]

My 97lx and friends 96lc do the same thing... I think it is the air intake? but what would I know I'm not a Dr.

 

[VCCruzr]

Glad to hear it is a normal thing on the later models cuz I never heard it on the '93LC I owned for 7 years.

 

[unimogbob]

Some of my 80's have done that; I have traced it out to a flat spot in the exhaust in some to clear the rear axle. Some have it some don't. rg

 

[alia176]

if you think the whistle sound is emanating from the engine bay, see if the four bolts that hold the throttle body to the upper intake are tight. Two on top are short, two on the bottom are long bolts. 12mm socket with a 6" or 12" extension will work. Bottom ones are kind of hard to see so use a flash light to see the bolt heads.

report back.

 

[ncduckman]

if you think the whistle sound is emanating from the engine bay, see if the four bolts that hold the throttle body to the upper intake are tight. Two on top are short, two on the bottom are long bolts. 12mm socket with a 6" or 12" extension will work. Bottom ones are kind of hard to see so use a flash light to see the bolt heads.

report back.

Thanks! I will do that. This whistle is different from the exhaust whistle, which I discovered this morning, both on this site and on my truck. The throttle body makes sense, as it explains why it would be throttle related as opposed to RPM related, like the exhaust whistle is.

Robert

 

[landcruising]

I had a very loud whistle when I purchased mine, a lot of it went away when I put the correct Toyota belts (non ribbed for his pleasure!!!) and replaced the idler pully. Something to consider if you did not use direct toyota parts. I still however have a whistle. I originally suspected the intake and the tuna can on the bottom of the air cleaner or the fender intake change in direction. It seems likely that the circular motion would replicate the turbo type sound. Eventually I got used to it.

That was up until 2 weeks ago I had to leave the tailgate down to transport my NTM bumper. That is when I could here a very definate whistle from the tail pipe, but it was unlike yours because it most certainly related to RPM,s. Anybody else experence this or could chime in?

 

[azcruizer]

That was up until 2 weeks ago I had to leave the tailgate down to transport my NTM bumper. That is when I could here a very definate whistle from the tail pipe, but it was unlike yours because it most certainly related to RPM,s. Anybody else experence this or could chime in?

Exact same issue for me. Transporting my ARB bumper (well, maybe not exactly the same) home with tailgate down. Definite whistle at about 2100 RPM, but only under load. In neutral and 2100 RPM plus--no whistle. Strange...

 

[alia176]

Thanks! I will do that. This whistle is different from the exhaust whistle, which I discovered this morning, both on this site and on my truck. The throttle body makes sense, as it explains why it would be throttle related as opposed to RPM related, like the exhaust whistle is.

Robert

Robert,

Any update?

 

[ncduckman]

No update yet. I haven't had time to dig further. I will post up when I do.

 

[edog's 80]

My '96 does it. I pretend it's my super turbo while everyone is passing me.

 

[Yuca]

I notice that whistle after I had all the belts replaced yesterday, and was told by the Firestone mechanic that the sound was coming from the alternator. So to prove, he had me put the the scope in my ears and placed the end of the scope on the Alternator. I could hear very clearly that the sound was coming from the alternator. Consecuently, the solution given, was to replace the alternator. Did not do that. Will wait and if the sound becomes umbearable will take to another mechanic for a second opionion, in case the belts are not properly installed or something of the sort.

 

[arndog123]

Glad I saw this thread because I was going to look into it this weekend. I have the same thing in the '96 but not on the '97.

 

[4x4labs]

The toyota whistle

This is a typical toyota exhaust whistle. Not just the 80 series has this. I have heard this same report from previa van, 4 runner, and various toyota car owners. I've had several Toyota trained techs at the shop verify that this whistling phenomena is typical of toyota exhaust systems. If you cut the resonator off your 80 you will experience an increased volume of the whistle. When we remove the resonator to install our rear bumpers the whistle becomes apparent whether it was there before the resonator was removed or not. Theres usually a knob on the radio that makes it go away, or pretend it's a turbo.

-luke@4x4labs

 

[retrofive]

I have never heard such a whistle before in my 94. MAF issue sounds like the the first place I would check. No MAF here so only guessing. Good luck