Is this chattering noise my transmission?

[Delta1Seven]

My truck makes a chattering/rattling noise that only occurs after a cold start. It noise consistently starts about 6 minutes after startup, and once the truck is fully warmed up, the noise goes away. This happens every single cold start, at almost the exact same time each time.

2024 about 8K miles.

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[icetaco]

Heya, we're twins. I posted the same thing back in November -
Post: https://www.tacoma4g.com/forum/threads/rattle-grind-on-cold-start.16725/
2024, Off Road, Non-hybrid, ~4900 miles. Not on transmission TSB. No codes, vehicle drives completely normal.

I haven't taken it to my dealer yet, but I'm about to once I hit 5k miles. I have the cat shield underneath, which is where it sounds like it's coming from - and that thing has a big ol proprietary screw that I'll need help from the dealer to get off.

FWIW, same exact thing as far as the delay. Never on an absolute cold start. I took a picture of the engine temp because this was a more reliable way to know when I'd start hearing it (more or less when it sits at that first ~1/5 mark, is when the noise is the loudest).

Did the dealer dismiss your video? That seems pretty definitive -

I did some searching in other places, and someone had posted this picture of his heat shield that he said was near the cat - and that those two heat shields were smacking each other rather than being loose. (the photo below is not my photo, that's the photo he posted). Unfortunately that's also under my cat shield so I can't poke at it myself, but given that the truck has to hit temp to start making it, I'd want to avoid poking around hot metal!

 

[Delta1Seven]

Heya, we're twins. I posted the same thing back in November -
Post: https://www.tacoma4g.com/forum/threads/rattle-grind-on-cold-start.16725/
2024, Off Road, Non-hybrid, ~4900 miles. Not on transmission TSB. No codes, vehicle drives completely normal.

I haven't taken it to my dealer yet, but I'm about to once I hit 5k miles. I have the cat shield underneath, which is where it sounds like it's coming from - and that thing has a big ol proprietary screw that I'll need help from the dealer to get off.

FWIW, same exact thing as far as the delay. Never on an absolute cold start. I took a picture of the engine temp because this was a more reliable way to know when I'd start hearing it (more or less when it sits at that first ~1/5 mark, is when the noise is the loudest).

Did the dealer dismiss your video? That seems pretty definitive -

I did some searching in other places, and someone had posted this picture of his heat shield that he said was near the cat - and that those two heat shields were smacking each other rather than being loose. (the photo below is not my photo, that's the photo he posted). Unfortunately that's also under my cat shield so I can't poke at it myself, but given that the truck has to hit temp to start making it, I'd want to avoid poking around hot metal!

Thanks for the reply. I’m non-hybrid as well.

The noise is extremely consistent, which is why I’d be surprised if it’s the heat shields. For them to rattle only during that narrow warm-up window, they’d have to be sitting at almost the exact clearance where thermal expansion causes contact only when partially warmed, but not fully cold and not fully hot. Since we’re talking about metal expanding only a few hundredths of an inch, it seems a bit unlikely. But I hope I am wrong!

That said, it’s still possible, and honestly I’m hoping it is something like a heat shield rather than anything internal or mechanical.

I don't have a lift but I'll try to crawl under my truck to take a look. Do you know if the photo of the heatshield you provided is from underneath the truck or looking down at the engine bay?

 

[icetaco]

From your video -

Different angle - but the you can see the stamped arrow right near the exhaust hook. The lip of the other shield is facing the camera directly. But given the video angle, can also see they aren't really touching.

I see my dealer on Tuesday. Plan is to get there an hour or so early, so the truck can cool, and walk out with the tech so we can all listen together 🥲

 

[Yotota]

Aside from getting Toyota to fix it, the only option I can think of is to use a metal rod to poke around while the noise is occurring. Not sure I'd trust wood around the cat/downpipe.

And if you touch it to your trans case and hold it to your ear, it will act like a stethoscope to amplify any internal noise. Or just use a mechanic stethoscope if you have one.

It could be one of the welded exhaust heat shields that popped loose, and only rattles at a certain point of thermal expansion like you said. I had an exhaust leak on an old truck that did the same thing from a small crack.

 

[Delta1Seven]

From your video -

Different angle - but the you can see the stamped arrow right near the exhaust hook. The lip of the other shield is facing the camera directly. But given the video angle, can also see they aren't really touching.

I see my dealer on Tuesday. Plan is to get there an hour or so early, so the truck can cool, and walk out with the tech so we can all listen together 🥲

Any update from your visit?

I was under my truck yesterday and found if I rotate this circled exhaust hanger, that the sound appeared to go away. When rotating this piece with your hand, it puts pressure/flexes the exhaust and eliminates the noise. I believe the noise is coming from where the blue arrow is.

I was only able to test this quickly once so far, so I'm not 100% this is the cause. It could have been a coincidence. I would love to know what you find!

EDIT: It may have been the next exhaust hanger rearward of the one circled, I can't remember. Anyhow, it was one of the two that I was moving around.

 

[icetaco]

Sorry for late reply - my appointment had to get moved. Got the truck back - initially they thought it was me hearing the direct injection - but when I showed them the video, it was enough to get the foreman involved. According to them they went hunting everywhere and concluded it was the cat shield - so they installed some insulation, cleaned up everything down there, and put the shield back on.

I let the truck sit for a few hours which is usually enough to get me a new set of chattering, and didn't hear anything. Gonna see how it sounds overnight.

I did emphasize that I knew a guy who had the same issue with no cat shield (i.e. you) and that we have identical chatter. They said they wanted to see how the insulation worked on my end, and would then let me know. They definitely acknowledged something was up and that it wasn't normal. I'm gonna watch this thing like a hawk and if I hear it again, will bring it back in.

 

[icetaco]

Alrighty, I think it's fixed. After my above post, it started up again. So I stuck a go-pro underneath and sat with my poker.

@Delta1Seven I pressed where you pointed out and like a magic trick, the sound went away. As soon as I let off, sound came back. Pressed, away, etc.. Photo attached.

The dealer ended up ordering the following
* 17451-0D140 GASKET, EXHAUST P
* 90501-A0005 SPRING, COMPRESSI
* 90109-A0064

I believe in my above photo, that is the spring coil to the immediate right of where I'm pressing with my poker.

Did a cold start yesterday, let it run for 10+ minutes, no sound.

Hope that helps you!

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