Loud Banging Sound from Under the Hood After Engine Shutoff on Hybrid Model

[Muaythaimountain]

Hi all,

In my most recent two drives, I noticed that after I shut the engine off and a minute or two later, there were one or two very loud banging sound coming from the engine bay. Mine is a hybrid limited model. Just want to check whether you guys have experienced it before. I can try to capture a video next time

Thanks!

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[Gfenza89]

You’ll need a vide for us, dealership will tell most likely tell you it’s normal unless there’s 6 quarts of oil, pistons, block material laying in their parking lot

 

[exia]

does it sound like a clunk or bang?

 

[TacoFreak]

That doesn't sound like any noise my hybrid has ever made. My truck doesn't make any loud noises after I shut it off.

If you can reproduce it for your dealer I would definitely take it in. It would probably also be a good idea to get that documented, even if you can't demonstrate it for your dealer. Good luck.

 

[StreeTaco]

I concur.. I get a weird sheet metal banging sound shortly after powering down the truck. It coincides with a servo sound

 

[TacoFreak]

Wow - that sheet metal sound is a new one. I do hear my truck doing some unknown stuff after I shut it down or even just when I first open one of the doors. But never anything that would make you wonder wtf was going on.

It seems very strange to me how differently identical trucks sometimes behave.

 

[Smugly1169]

could it be the auto closing/opening louvers on the front of the truck in front of the radiator?

 

[Muaythaimountain]

Here comes the video. It always starts with a hissing sound like pressure relief and some electronic sound, and then followed by a clunk/bang. The bang is at 00:23 in the above video. Also it doesn't sound like it's from the engine compartment. It's more like from underneath the car on the driver side (the gas tank?)

 

[exia]

Here comes the video. It always starts with a hissing sound like pressure relief and some electronic sound, and then followed by a clunk/bang. The bang is at 00:23 in the above video. Also it doesn't sound like it's from the engine compartment. It's more like from underneath the car on the driver side (the gas tank?)

My model does the exact same thing I’m assuming it’s normal. Release heat maybe.
?

 

[SnowmanJPS]

I'm willing to bet that's some funky evap/emissions testing sounds you're hearing, but if someone else could chime in with the facts that would be great

 

[evlfred]

also be the electric brake booster, I put one out of a tesla in my 69 C10 and it makes a clicking several minutes after shutdown. Really freaked me out first time I was in the garage when it did it.

 

[bresna]

Toyota's hybrid vehicles are classified as SULEV (Super Ultra-Low Emssions Vehicle). I don't have a hybrid Taco but on all of my other Toyota hybrids, this sound is the truck pumping hot radiator fluid into an insulated storage tank. This is done so that when you start the vehicle "cold", it isn't cold for very long which is important for an SULEV vehicle, as that's when a lot of the "bad" emissions happen. This thermos full of hot radiator fluid will allow the truck to heat up much faster.

 

[TacoFreak]

My truck does warm up really fast, especially compared to my Tundra with the 5.7L V8, which took forever. I had not heard about that system before @bresna, thanks for that info. I have never heard any loud banging after turning off my truck, but maybe I just haven't been there at the right time yet.

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