Solved - Help with unusual engine noise

My engine started making this whining noise. It's loud enough to hear inside the truck. It seems to be getting louder as each day goes by. I have to admit I'm stumped.

- I popped off the Serpentine Belt, but the noise remained. That eliminates the Alternator, AC Compressor, idler and tensioning pulleys, and the fan bearing

- My timing belt is ~ 5 yrs ans ~ 30,000 old (Aisin kit with new bearings and water pump), I popped open the cover, and the belt is pristine, show no belt dust or debris as might be expected with a loose/wobbly idler or tensioning pulley).

- But here's what has me stumped...the noise does not change with increases in RPM. It remains the same pitch/volume at any RPM.

- It sounds sorta like a motor running, but I'm not VVTI.

- It seems to be coming from/near the throttle body or manifold.

- Has anyone else had a similar problem?

https://youtube.com/shorts/vUNQJb9O3ao?feature=share

 

Does it go away after a drive? Any lights on the dash ?

 

I went back out to listen some more...no noise, until it warms up! Then noise...

 

I have these, thanks...but I can't hear the noise no matter where I probe.

 

No lights, no codes, it does not go away after a drive.

 

Vacuum leak. Possibly at the brake booster.

 

Secondary air pump stuck open?

 

Whine stays the same up to redline & through gear changes? Abs module?

 

I can check for that, but would it not change with RPMs?

 

In the case of the brake booster the amount of vacuum is regulated so yes, it would be consistent at nearly any RPM.

The problem with this is that you will not be able to use carb spray to find the issue. It will take a while for the air to get to the engine.

 

I haven't taken it to redline, but ~ 3000 or so just to listen for a change...no change. ABS pump is on the other side of the truck, no where near the the noise. I'll put the stethoscope on it anyway just to preclude it.

 

I don't have a secondary air pump...NOT VVTI

 

So searching on here using this query Search Results for Query: ENGINE HIGH PITCH | Toyota Tundra Forum
Most common is a manifold vacuum leak.

 

Any recent work done at all?

 

Hmmm...I was going to try with gas. What do you suggest?

 

I changed the spark plugs recently.

 

Disconnect it and plug the hole into the manifold so you don't have a gross leak.
There may be other potential sources of vacuum leak. You can do the same for those.

 

See this specifically from @bmf4069 https://www.tundras.com/threads/sec...fo-and-instructions.90175/page-2#post-2933029

 

Well I'll be damned! Although not a vacuum leak per se, it was nonetheless the right path to follow. The PCV vacuum hose is soft and collapsed, resembling a duck call!

https://youtube.com/shorts/IPY8wy13qO0?si=XxVfwnKjfStXaoL_

Yes (shame on me) it's not an OEM hose. I changed it out a year or so ago with a cheaper eBay part (it's just a hose, how bad could it be? <sigh>). I put the old one back on, and am ordering a new one now.

Thanks everyone. Case closed.