Help identify this whistling noise

[VAL]

My truck started doing this weird whistling noise. I only happens when I'm driving down the street between 15-30 mph, doesn't happen when idling in park when revving the engine. I've checked the vacuum lines, carburetor, belts, etc. Any help would be greatly appreciated.
http://youtu.be/K36gaBLBH3I

 

[J Knight]

Does the whistle coincide with engine rpm or a certain gear?

 

[VAL]

Does the whistle coincide with engine rpm or a certain gear?

Both, It only happens after 3rd gear, and when cruising at 15-30mph. If I accelerate it goes away, and if I let off the pedal it goes away. Only happens a cruising with the pedal slightly depressed

 

[J Knight]

I was thinking vacuum leak or belt speaking but if it only does it in 3rd gear might be a trans issue if you can't get it to whistle in lower gears under the same load. Just a guess.

 

[350runner]

Send the wheels and tires you me for further diagnosis. Seems as that combo has issues with molecular stability.

Sent from the dust in front of you!

 

[350runner]

Seriously tho.... is the driveshaft yoke rubbing the t-case, brake pad wear indicators, sounds like it's drive line related.

Sent from the dust in front of you!

 

[VAL]

I'm getting ready to lift the front end off the ground and rotate the wheels, I also noticed I have a transfer case leak. The drive shafts look good.

 

[350runner]

Darn I wish these old trucks didn't leak

Sent from the dust in front of you!

 

[VAL]

Well, I finally found the whistler. It was a bad u-joint at the slip-joint part of the drive shaft. Replaced it, and no more whistling and no more vibration.

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[350runner]

Awesome!

Sent from the dust in front of you!

 

[J Knight]

Wow...never heard a u-joint make that kind of noise.

 

[MadOgre]

Ya me neither. Good to know Glad you got it beat.

I was wondering why there was so much vibration in your video. Seemed like a real rough ride

 

[VAL]

Ya me neither. Good to know Glad you got it beat.

I was wondering why there was so much vibration in your video. Seemed like a real rough ride

At first glance and visual inspection, everything seemed normal. The cups on the u-joint weren't at all cracked or deformed in any way and I couldn't feel any play. The pins inside were thoroughly rusted, and fell out upon removal. It wasn't until I put the rear on jack stands, had my nephew start the truck and put it in drive, and watched the shaft. It didn't make the whistling noise or vibrate until the brake pedal was depressed slightly, and put resistance on the joint, while the truck was rotating the rear tires in drive. Only then was I able to pinpoint the whistling sound and noticed the shaft wobble. I had been dealing with this for about two weeks, and absolutely checked everything from belts, brakes, accessories, vacuum lines, etc.
I guess that's what I get for using the cheap non-greasable Autozone u-joints. I put some Neapco USA brand greasable u-joints this time.
Maybe this will help someone down the line with a similar issue.

 

[Don5]

I am glad you got it figured out before the driveshaft dropped! I had that happen in my truck years ago. The top u joint let go and the driveshaft bounced off the ground while I was pulling out into traffic. I immediately pulled over and unbolted the driveshaft. I went home in 4wd that night. I replaced the u joint and thought nothing more about it. About a month later the bottom U joint let go. Go figure. So I slid the driveshaft out and went home in 4wd. I replaced the U joint and had no problems for a long time.

My motto is this- I replace both at the same time as a preventive measure from now on. Why take a chance?

BTW- You have a nice truck VAL.

 

[VAL]

Yeah, I went ahead and had them both changed out, I had a gofer( gofer this, gofer that) for the day(my nephew). He actually did the whole job under my supervision. He's been bragging for the longest of time about the things he's learned in auto shop class at school for the last couple of years, but when I asked him to remove and replace them, he didn't even know what a u-joint was. Go figure!
Well anyways at the end of the day, both u-joints were replaced, and my nephew learned something new. And the best part, the labor only cost me a trip to Burger King.
And thanks for the compliment Don5.