Mystery Bang

I've got myself a mystery "bang" on my 2006 DC 4x4 Tundra. If I drive the car (can be as short 2 mile drive), and then turn the car off, I get a bang sound a minute or so after the truck is off. Sounds much louder than "cooling tings". Happens every time. Haven't modified anything recently. It's so loud when it happens I can hear it in my house while the truck is parked outside (see photo).For clarification, the truck is off and no CEL when on.

I attached two videos of the sound (one in the cab, and the other from under the hood[end of video]).
https://youtube.com/shorts/jg4QaeloZ14?si=dLEHz_rOmVuVB1uh
https://youtube.com/shorts/DpYnOUscQts?si=u1Mk5N6OWw6BrILz

There is a thread here that seemed to think it was the cats (can't remove mine in California): https://www.tundras.com/threads/loud-bang.141939/

And a thread here that seemed to think it was low transmission fluid (I topped off trans fluid to rule out): https://www.tundras.com/threads/clunk-sound-after-turning-engine-off.92037/#post-3913817

Hoping the expert community can help on this.

Thank you

 

Man that's weird. Never heard anything like that. I'm curious to see what other members suspect it might be.

 

All I got is it sounds like something metal moving as it cools down and contracts.

 

Nothing wrong with a good mystery bang. But damn, those penicillin shots hurt.

 

Yeah, that's metal contracting as it cools. Check all of your heat shield bolts. Might be loose or missing one. Not abnormal.

 

It almost like the sound a starter solenoid makes when you have a close to dead battery with not enough juice to crank over? Coming from driver side top or bottom of engine compartment?

 

Thanks for the replies so far. I think the consensus is right; it sounds like metal contraction. I just don't understand why it's so loud or how it started. I can feel it in the floorboard if I sit in the truck. It's alarming when it happens. I'd like to think that this is normal, but it's not really normal since it just started doing it.

I can't tell which side it's coming from, and I'd guess bottom. I've been under the truck when it does it and still can't figure out for sure where it's coming from.

All the heat shields look fine to me. Nothing is loose. I'll take a better look at the bolts this evening.

Thanks again for the interest so far. Just curious to see if anyone has experienced this and found a solution.

 

Does your truck have a manual transmission and a clutch start cancel button?

 

LOL...sounds like an option at the whore house.

 

No MT option for the DC

 

Next time you shut it off, crawl underneath and inspect. You’ll probably hear it really well down there and can begin to pinpoint a more accurate component causing the noise.

 

Something exhaust related. Probably a heat shield. Since it heats and cools quickly it has a lot of surface area but little mass.

 

The echoey reverberation after the sound makes it sound almost like the thing making the noise is full of a liquid.

 

Yes. And it almost sounds spring-loaded.

For clarification, the sound I'm referring to is at 0:04 in video 1 (IMG 2051) and 0:24 in video 2 (2025 05 13 10 41 45).

I can imagine just hearing the sound and not poking around to solve the problem is a lot to ask. Pretty much just putting this on the World Wide Web in case someone has experience it and has found a solution. I'll eventually get to the bottom of it and post the solution for the next person.

Heat shields all look good. Being under the truck does not help me figure out where it's coming from. I will say that the truck has also developed a little "rumble" or vibration at idle at a stop light. Not a miss or combustion related. Kinda feels like the power steering pump is struggling. But not sure that's related (mentioning this because the two kind of started in the last month). Trans mounts look fine.

 

The only way you're going to find it is to be under the truck when it happens, so change what you're doing until you find it.
- Move around to different spots under the truck.
- Wear thick leather gloves and put your hands on different parts of the exhaust and heat shields to see if you can feel it.
- Get a 3 foot l length of hose/tubing. Hold one end up to your ear and stick the other end at different locations under the truck.