2021 Crewmax rumble on cold start

2021 CM hás had a gruff sound to it the last few mornings on cold start for first time ever. 3000 miles on it since December. The gruff/rumble only lasts for a second, but it’s noticeable. It won’t do it unless it’s been sitting overnight. Anyone had anything similar? Thanks a lot!

 

Trrus001
This could be your cooling fan engaging for a brief moment and then disengaging. My 2020 CM does the same thing on start up and then is fine for the rest of the day. To be sure raise the hood before start up, stand to the side and have someone start it and watch your fan.

 

My 20 has made similar sounds. I don’t remember my 11 doing it .

 

I've also experienced this, it's only when sitting for a whole day in cold weather. Only happened maybe 3-4 times for me in 1 year ownership. Have not mentioned it to the dealer yet

Like a metal grinding sound for a split second, then it's gone

 

Same thing; not sure why it does it, but it does it for a split second and that's it.

 

Happened to me for the first time on my 19’. I wasn’t been able to replicate after the initial start either.

 

Glad to hear it’s no big deal. Sounds like exhaust back pressure almost to me. Coming from passenger side front it sounds like, but it’s so quick I would have to be outside like mentioned. Loving the truck, just had never heard it before until the other day. Thanks for the input!

 

My guess is lifters are bleeding down overnight and they rattle until oil pressure builds up. No worries. mine does it also.

 

Does this motor have lifters? It's overhead cam

 

Yes it still has them even on a DOHC, they call them hydraulic lash adjusters.

 

Mine did it twice when I was out of town and it got below 0 overnight. Never did it when started in my garage. Sounded like something spinning up for a second after starting. There was another thread about it with a video that had the same sound as mine.

 

On my 2020 CM with ~9,000 miles I've noticed two distinct sounds during a cold start. One of the sounds is what I would call a combustion knock "growl" that only occurs for 1-2 seconds. That sounds like what you are referring too. Really short burst but clearly there when you let the truck set overnight on a cold day. I think it's a hole in Toyota's calibration where it is transitioning from cranking to running at idle. I likely goes into a major advance mode that causes that "growl" and then quickly transitions back to a normal idle mode. I want to record it to show the service manager but it takes two people to time everything just right. Open the hood, get in position, etc... I don't think that is a desirable thing for them to have in their engine calibration. Hopefully they are working on a fix. The other sound I hear is on the first start of the day. Something is slipping in the belt drive system. If you start the truck and let it go to low idle everything is fine. Turn the AC knob on, or add any accessory load and you will hear a screech/chirp. Not high pitched. Also very short duration. It does this about 50-60 % of the time and after it does it, it doesn't do it again for the rest of the day no matter how many starts you do. Of course, there is a third sound which is that massive fan spinning on every start that makes it sound like you are standing on the throttle when you are not. That's the F-16 taking off sound that isn't enough to hide these two other items. I hope to record both of those sounds and take the truck to the dealer. I'm worried one will wear out the belts prematurely and the other is anyone's guess if its a problem.

 

Unfortunately can’t help with the problem and or suggest anything. But for what it’s worth I’ve 100% experienced the belt squeal you talk about when I turn on heat or AC. scared the crap out of me lol. Also made me wonder so if I shut my truck off with the AC full blast and then I remote start it, does it do that sound while I’m inside? I’ve been hesitant ever since I heard it a few times and since then I start the truck then after like 30 seconds of idle I’ll turn on AC and the problems isn’t there. Don’t wanna be ruining a compressor or whatever else would make that awful sound on a truck that doesn’t even have 5k miles yet...

 

Soooo I'm pretty sure I read a big discussion on this awhile back. My '19 does this every time is sits longer than a day. It is definitely the AC Compressor on my truck. You can test yours by turning the AC off or turning it totally off before you let your truck sit a few days, then start it with AC already off to see if the sound is gone.

From what I remember this is "normal" & a lot of these trucks do it. I think maybe it's the electromagnetic clutch or bearings sitting too long or something. I actually decided to run a little experiment & drove about 20 miles with the air off to see if it went away once the clutch was "warmed up". Sure enough, drive 10 miles, came to a stop, and turned the AC on. No noise. So maybe the bearings lose their lubrication or something from sitting. Hopefully it's harmless or maybe it'll blow up on all of us lol cheers