Ticky Ticky Ticky Rapid Sound when coming to a stop

Good Morning. I was driving my 2000 Toyota Tundra this weekend when all of the sudden I noticed a new sound. Like a rapid tick tick tick sound coming from the driver side of the engine. I stopped and shut the truck off and it went away. Started back up and started driving when I came to another stop sign and it started again. I drove it 35 miles without a stop sign or stop light and it was fine. Came to another darn stop sign and it started again. It goes away when you shut the truck off. I also noticed if I'm at a stop sign and Rev it up, it goes away, but as soon as the idle gets back down to about 1000 rpm it starts back up.

Truck just turned 140k, has the 4.7 L, timing belt done at 96k. What would cause this sound? Is there a cam position or timing sensor that is making it go wacky? Truck runs fine, hasn't set of the CEL yet. Just makes that rapid fire machine gun sound when I come to a complete stop.

Thanks for reading, thanks for any suggestions on what I might do to correct the issues

 

Sounds like a heat shield for the cats or exhaust is loose. When the exhaust cools down, check all the shields for any missing bolts or see if you can replicate the sound by tapping on them.

 

Was the AC or defrost on?

 

I will check it out when I change the oil this weekend. Just odd that it won't make the noise any other time unless you stop, and won't go away unless I shut off the truck.

 

No AC or Defrost on at the time. Might have had the heat on as it was chilly that evening.

 

https://youtu.be/62Hr_XW8cL8

Here is a video of the sound in question

 

That ain't a heat shield. Sounds like a low pitch thud. Check your mounting bolts for the alternator and power steering pump is on that side as well. Put a mechanics stethoscope or rubber hose to the valve cover and listen. Hopefully you can determine that its not the valvetrain that way. It may be accessory belt pulley related. Low rpm allows a harmonic vibration to occur, then when you gas it up, the extra spinning creates additional load on whatever is loose, temporarily eliminating the noise.

 

Well it was a vacuum line that popped off...sometimes its the simplest things, but a cheap fix too! Thanks to all that placed their input.

 

Thanks for responding back with your solution finding. I’ve had a few of those many hoses on our trucks come loose and cause weird thing to happen. Wonder why Toyota never put hose clamps on those smaller hoses?

Anyways, it pays to put some clamps or zip ties on for added security. Cheap insurance!

 

Agreed, I'm going to zip tie it for sure. I think when it was getting worked on the day before with the steering shaft the tech might have knocked it loose when messing around under the hood as it never did it before.
Not even 1 second into the video it shows the hose that is off. I could of swore it was internal VS external. Also I noticed as I moved my phone it was loud when it was right above the hose.
Maybe this will help someone else out in the future. Great site, great response. Thanks to all!