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Discussion Starter #21
The noise seems to only occur after the truck has been sitting overnight and has cooled off completely. It will not occur if the truck is restarted after already being used that day. The cold temps definitely has something to do with it. The heater is in the defrost position and the fan is on low. I'll try it with them off tomorrow morning and see if there's a difference. I didn't notice this sound last year, but I kept it in the garage. To me, it sounds like something isn't getting lubed on startup.
 

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Discussion Starter #22
Mine makes the exact same noise every COLD morning I start it up. First time it did it I thought it sounded like a vent that was opening or closing, then I thought it was a belt. Only does it when temp is below 30 degrees. Sometimes it does it longer than others. Very odd.
Hey Nitro, interesting that you have the same thing. When I noticed this the other day, that sound went on for about 8 seconds I'd guess and then gradually faded away.
 

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Mine has had that squeal for two winters now. It happens when it has sat for a day or two or when it gets cold. I was told that it and the knock was normal and not to worry, so I don't. I just keep putting fuel in it and drive baby drive.
 

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I am sick of explaining these noises so here goes again on the squealing (those of you that think the knocking sound is piston slap are beyond my help).

The Tundra is equipped with two (yes two) small air compressors that blow air down the exhaust pipes into the catalytic converters for some emissions related reason on start up. They make a squealing noise on a "cold motor" start up, even on a warm day you can hear this if you pay attention. On a really cold day they make the same noise only much louder, most likely due to frost forming on the internal compressor components.
 

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Discussion Starter #25
I am sick of explaining these noises so here goes again on the squealing (those of you that think the knocking sound is piston slap are beyond my help).

The Tundra is equipped with two (yes two) small air compressors that blow air down the exhaust pipes into the catalytic converters for some emissions related reason on start up. They make a squealing noise on a "cold motor" start up, even on a warm day you can hear this if you pay attention. On a really cold day they make the same noise only much louder, most likely due to frost forming on the internal compressor components.
The squeal sound I posted sounds completely different from the compressor sound that I'm familiar with. Not even close. Plus, it does not match the timing of the cat. compressor and does not sound like its coming from the same location. The regular compressor sound comes from the engine bay, this squeal is coming from under the truck.
 

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The squeal sound I posted sounds completely different from the compressor sound that I'm familiar with. Not even close. Plus, it does not match the timing of the cat. compressor and does not sound like its coming from the same location. The regular compressor sound comes from the engine bay, this squeal is coming from under the truck.
Whatever you say. You're wrong, but I will never convince you. Take it to the dealer so the techs can laugh at you after you leave too, those guys can always use a good laugh.

Anyway here is a PDF explaining the components.http://www.mr2.com/files/mr2/techinfo/Random FSM Data/052uz-15.pdf
 

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I am sick of explaining these noises so here goes again on the squealing (those of you that think the knocking sound is piston slap are beyond my help).

The Tundra is equipped with two (yes two) small air compressors that blow air down the exhaust pipes into the catalytic converters for some emissions related reason on start up. They make a squealing noise on a "cold motor" start up, even on a warm day you can hear this if you pay attention. On a really cold day they make the same noise only much louder, most likely due to frost forming on the internal compressor components.

By far I am not a mechanic (in fact when it comes to this stuff I am stupid) but the noise seems like it comes from the driver side of the motor possibly to the rear part of the motor between the wheel and fire wall or under the driver's side of the cab and if that is where these compressors are located then that would make sense to me.

I drive 3 miles to work and it is by far the loudest and longest lasting after the truck sits during my 8 hr night shift. I have yet to hear it after I drive home and wake up later in the afternoon. I am assuming that may be because of the heating of the sun.
 

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Discussion Starter #28
Whatever you say. You're wrong, but I will never convince you. Take it to the dealer so the techs can laugh at you after you leave too, those guys can always use a good laugh.

Anyway here is a PDF explaining the components.http://www.mr2.com/files/mr2/techinfo/Random FSM Data/052uz-15.pdf
Yeah, whatever man. What's with the cockiness?

Anyway, thanks for the pdf. However, it states right on the first page that the injection system only operates when the coolant or air intake temps are above 41F. The truck sat overnight and it has been well below 41F here and was in fact around 9F when I started the engine. So the pdf confirms that this is NOT the cause as the injection system does not operate at these temps.

Thanks.
 

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Mine will make the same noise on cold engine below -25c. The belt does make some noise as well and I can smell burnt rubber for a few seconds. Have you got the block heater? Plugged in it starts much quicker and quieter. Tranny warming off of the engine is nice too. Coldest start so far has been -35c. I try and plug it in for an hour or two first.
Doug
 

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Hi Seadragon, My 2008 just started doing the exact same thing.
Squeal at startup on first start of cold weather -10 to -20 C.

It will squeal only on the first startup of the day 3 to 8 seconds.

My first guess will be to test if it is the belt by using a light spray of belt dressing.


Could just be a dry/hard spot on the belt.
As it warms up, it gets softer/more flexible.

Worth the effort.

2008 Crew MAx 4x4 5.7 under 5K
 

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It can be very deceptive where exactly the sound is coming from. I think I know the sound you're hearing seadragon. I've had it since day one if it's cold, and I thought it might be coming from below me when I started the truck but I checked once with the hood open and it was the power steering pump pully. After a few seconds it quiets down, I'd have to guess after the power steering fluid stops being a jelly and becomes somewhat liquid again.
 

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mine appears to be coming from the air pumps

but as far as the knocking its normall the 1st gen tundras did the same thing its normall and doesnt hurt the engine ive seen 300k on a 02 model 4.7 knocks like hell till it warms up but runs like a champ

ford does have a version of their vvt but for the sohc motor but really it doesnt matter its still a ford
 

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Discussion Starter #34
Keep in mind that the air injection system does NOT operate in temps below 41F according to the pdf posted earlier in this thread by someone who was quite insistant that this is what the squealing sound was.

The temps were warmer here today and I did hear the regular injector sound that we're all familiar with. (like a faint whine for about 15 seconds). Again this was not the same sound that I heard when the temps were cold.

The squeal sound came from under the truck.
I'll check the belts for noise when it gets colder here again. But it does sound like something mechanical. Even my neighbor looked over when it squealed with the look of "what the hell is that?"

Next time I'm at the dealer, I'll mention it to them.
 

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It can be very deceptive where exactly the sound is coming from. I think I know the sound you're hearing seadragon. I've had it since day one if it's cold, and I thought it might be coming from below me when I started the truck but I checked once with the hood open and it was the power steering pump pully. After a few seconds it quiets down, I'd have to guess after the power steering fluid stops being a jelly and becomes somewhat liquid again.
And sometimes its known that this power steering pulley bearings can go dry! One of the reasons why I had to get it done on my 2003 Tundra back when I had it.

Sanosuke!
 

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I had the same problem whe I bought mine in Nov 07 when it got real cold. Hasent done it this winter so far. No big deal IMHO
 

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Discussion Starter #37
It's the fan.

For those interested, I think I found what the squealing sound is...

The clutch fan.

My truck sat for the last 3 days in my driveway with nightly temps around -25C (-13F). Started it up this morning and there was a faint squealing sound. The sound kept going so I walked around in front of the the truck. The squealing sound then intensified at the same time that the fan dropped down in speed. It then faded and eventually disappeared. It was definitely tied to the speed of the fan.

Anyway, just thought I'd share that observation.
 

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Seadragon, mine does the same thing almost every morning, I thought is coming from some belt but now that you mentioned the fan I'll pay more attention to where it's coming from. By the way I too am in Ontario, same weather/temperature. It did it last winter too and never got worst, about 2-3 seconds for me.
 

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Seadragon, mine does the same thing almost every morning, I thought is coming from some belt but now that you mentioned the fan I'll pay more attention to where it's coming from. By the way I too am in Ontario, same weather/temperature. It did it last winter too and never got worst, about 2-3 seconds for me.
Ever since it's been dropping below 10F mine's been squeeling like a pig. It's _loud_. Lasts for a minute or so.
 

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Discussion Starter #40
Yeah, it's probably not hurting anything (I hope), but I'm just glad that I finally know where the squeal is coming from now.
 
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