whistling sound under moderate load, anyone?

[diverscale]

Hi, would like to know if it's a normal behaviour for our trucks to produce a slight whistle sound under moderate load.

I have pinpointed the ''problem'' to be coming from the air intake system, due to the sound be produced only on ''drive'' and under certain loads. On idle, or revving on neutral will not produce the sound.

The sound can be produced under moderate acceleration, between approx. 1500-2500 RPM only. Sound will not be created under full throttle, or under light throttle or idle.

After much research, the only post I found on the subject is this one:

http://www.toyota-4runner.org/5th-gen-t4rs/93835-trd-cold-air-intake-whistle.html#post823909

I removed the intake system and looked into this a bit, found out that after the T/B, there are a few sharp edges that could produce the sound. With no intake tubing on (everything removed before the T/B), the sound seemed a bit louder when running the truck on a short distance. I do not think that this is detrimental to the engine, as I could not find any leaks, but I would like to ear if anyone else have or had the same issue. Thanks.

 

[FactoryRide]

I've got it as well. You'll get use to it.

 

[brockeverly]

I had the same sound on my 2010. Almost like an electrical whine. Had it for 30k and never had an issue, I would say it is pretty normal.

 

[diverscale]

I appreciate the feedback thank you.

As long as it's not "abnormal" or detrimental to the engine, I'll accept a slight whine under certain conditions, and the best of it is that is nearly sounds like my turbo car lol.

 

[bofa]

I thought it was the wind passing between the mirrors. I just pretend it's a S/C. :banana:

 

[wheeliemert]

I think it's the valves doing their thing. My mechanic told me the engine has those valves to make it more efficient. I tell myself it's like a booster kinda like a turbo! Ha

 

[terra4r]

throttle body or close to. even more amplified with an intake. a good amount of toyotas do it.

 

[rigtec]

Hi, would like to know if it's a normal behaviour for our trucks to produce a slight whistle sound under moderate load.

"I have pinpointed the ''problem'' to be coming from the air intake system, due to the sound be produced only on ''drive'' and under certain loads. On idle, or revving on neutral will not produce...."

Hi diverscale,

Have you considered the "radiator cooling, clutch fan"?? The sound that you describe brings to mind, the sound of forced air, whistling through a channel of baffling. Being an "Air Conditioning technician" on the commercial end of the industry, I know that this sound only takes place under certain conditions involving: air speed, velocity, static pressure, surface angles 'in degrees', etc...

As you know, the fan clutch is a hydrolic device attached to the fan, that controls the engine coolant temp by adjusting is own speed, to manage the amount of air flow through the truck's radiator.

When you 1'st start the engine, the clutch fan will ALWAYS, start (temporarily), at the very same speed where it left off when the engine was hot. It's controlled by a thermostat, located directly on the front of the clutch body, and will take a minute or two, to find true ambient temp. In the mean time, the air velocity that's forced through the air passages under the hood will be excessive, potentially causing whistling, even howling.

You can make a few tests, observing the fan; whether it's operating at engine speed, or if it has "demodulated"; considering the actual cold air (ambient) temperature.

You can even restrain the fan, holding it in place during engine upstart (this is very dangerous, but I do it when I need the fan noise out of the way when listening for some other problem). The clutch will allow it to slip so it can be held still with almost no effort. Hope this is helpful,

rigtec, Cheers

 

[westwind77]

I know I get the same with my AFE dry filter. Was quiet before, then that slight whistle, with the swap of the filter. There is a an AFE thread and for those who installed it got the same whistle. So even with the stock intake even a filter swap from OEM will cause it.

 

[rigtec]

I know I get the same with my AFE dry filter. Was quiet before, then that slight whistle, with the swap of the filter. There is a an AFE thread and for those who installed it got the same whistle. So even with the stock intake even a filter swap from OEM will cause it.

Exactly westwind. This is a phenomenon, having it's foundation in physics; the by-product of some other very powerful principles.

rig

 

[mthrtrkr]

Going bonkers

I just bought a 2015 SR5 and I am hearing the same issue. It is kinda driving me nuts, wondering if you have since located the issue or if you have just learned to live with it.

Right now I might just need a support group to tell me "it's all ok"

Hi, would like to know if it's a normal behaviour for our trucks to produce a slight whistle sound under moderate load.

I have pinpointed the ''problem'' to be coming from the air intake system, due to the sound be produced only on ''drive'' and under certain loads. On idle, or revving on neutral will not produce the sound.

The sound can be produced under moderate acceleration, between approx. 1500-2500 RPM only. Sound will not be created under full throttle, or under light throttle or idle.

After much research, the only post I found on the subject is this one:

http://www.toyota-4runner.org/5th-gen-t4rs/93835-trd-cold-air-intake-whistle.html#post823909


I removed the intake system and looked into this a bit, found out that after the T/B, there are a few sharp edges that could produce the sound. With no intake tubing on (everything removed before the T/B), the sound seemed a bit louder when running the truck on a short distance. I do not think that this is detrimental to the engine, as I could not find any leaks, but I would like to ear if anyone else have or had the same issue. Thanks.

 

[diverscale]

I just bought a 2015 SR5 and I am hearing the same issue. It is kinda driving me nuts, wondering if you have since located the issue or if you have just learned to live with it.

Right now I might just need a support group to tell me "it's all ok"

I do not have my 5th gen anymore, but I have isolated the problem to be a normal sound/issue by the number of other people having the same ''issue'' (which is not an issue really). I would not worry about that anymore.

 

[Toyojay]

I'm hearing the sound too, but you guys are calling it a whistle. It sounds more like a whine to me, similar to a power steering pump failing but clearly not. I've already listened to all the bearings in the serp belt system. It IS relative to RPM, and I've had several techs I know listen to the sound and all are telling me its normal.... but I've had alot of vehicles (5 of which have been Toyota's) and I've never heard of this being normal before.

Is the general consensus after all this time still the intake system or the vacuum switching valves?

 

[jspagna1]

Ya I've had my 2011 T4R since new and I still hear it when I pay attention!!!!

 

[SumDumGuy]

Since I do not have a 4runner yet I cannot say for sure, but my wife has a Sequoia and I have a whistle/whining sound on that. I researched it a bit and apparently there is a screen on the throttle body which causes the noise. Not sure if that's the same as the 4runner.

If you look up this issue or throttle body screen removal for the Tundra/Sequoias you should see some examples.