Cold Start on an Incline Noise

I have a 2021 4-cylinder Tacoma that sometimes makes a loud noise from the engine at startup after sitting overnight (see youtube video) on my driveway. My driveway is on an incline, with the front of the truck higher than the back. On cold days, I may also get a "Low Oil Pressure" warning, which turns off once the engine warms up or is level. The engine oil level is optimal. However, neither the noise nor the warning occurs when the truck is started on a level surface. Any ideas on what might be causing this?

 

Anyway you can roll back to more level ground before starting?
Also, when checking your oil on level ground is your oil dipstick near the top dot?

You could get a long PVC pipe. Put your ear at one end and CAREFULLY poke around to determine the location of the noise.

 

Try parking the other direction? Maybe? Back into your driveway.

 

Yes, but I don't have any issue like this with any of my other cars. I had it in the dealership and all the fluids were fine. Any idea what the noise is?

 

where I park is an incline too
not much, maybe 5 degrees or so
how much is yours
more info is helpful in getting good suggestions
check the engine oil yourself on a regular basis (at least every 2-3 weeks)
don't rely on "dealer" for this simple maintenance issue just like tire pressures

 

You just diagnosed the problem

The noise and warning light are trying to tell you the oil pressure isn't enough on startup

How much incline are we talking? 20-30 degs?

 

maybe if its parked on an incline, most of the oil has drained to the lower end of the pan, leaving the crankshaft and rod bearings exposed/dry, and you are hearing a rod knock until the oil pump gets things lubricated again.

 

The crank and rod bearings are never supposed to be submerged in oil, either running or not running.. that only happens when the oil level is accidentally overfilled. And when the engine starts up the rotating assembly beats the oil up into a foam (like mixing cake batter in the kitchen) and can cause oil pump cavitation and loss of oil pressure. Not good.

The only way the crank, rods and bearings get their lubrication is from the oil galleys/passages.. by design..

 

I'll bet @Bishop84 could answer the OP's question after listening to the video in the first post.

To me it sounds like a PCV valve when I shake it in my hand really fast.

 

That is absolutely, positively, unequivocally, NOT the PCV valve.

 

Pcv valve won't make the oil light flicker on

 

I would park on level ground overnight and see if the problem persists. I have a feeling its not related to being parked on an incline...even tho you said it never does this on flat surface.

It sounds like the classic VVT-i cam gear clatter on cold start. It rattles until oil pressure builds up. This is a common-ish issue for the 2TR-FE on VERY cold starts or after sitting undriven for ages. But it shouldn't throw the oil pressure warning and it should only happen once in a blue moon.

We've been seeing more of the VVT-i rattle on the post-covid era 3rd gen 2.7s. Some others on here recently had their entire engines replaced because of this since replacing the entire VVT-i assemblies apparently didn't fix the issue. Those cases were 2019 and newer.

Good luck.

 

It's the VVT-i cam gear rattle. Its super obvious.

 

the design of the oil pan prevents exposing the pick up if the front of the truck is tilted upwards, you'd have to be on a severely steep decline to expose the pickup and at that point the front half of the crank would be submerged and you'd have other issues.

 

Yeah it seems to be popping up a bit to be slightly concerning, wonder if you could get toyota to fit the bill. The old tried and true looks to no longer exist.