Grinding noise diagnosis

[Mutant]

https://youtu.be/tlilHc0UyIk
EDIT: ITS THE BRAKE ACCUMULATOR/PUMP MAKING THIS NOISE

My searches have been inconclusive. When I start the truck cold, at about 70 degrees F ambient temperature (AC OFF) the engine starts this metallic grinding noise after a few seconds. It only lasts a few seconds then doesn't do it again. Yesterday it did it only once briefly while driving. I was thinking it's a pulley but the sound seems to be coming from driver's side rear of engine block which is scary.
Does anyone have experience with this awful sound?
I use this truck for work and need it 100% reliable.
BtW, timing belt , water pump, and drive belts replaced 20k miles ago.
This noise started after hard mudding in 4Low locked. Co-worker's Ford Raptor was stuck and I had to pull him out. I got stuck in the process but eventually got us both out. I'm worried that too much stress was put in the engine
I appreciate any help

 

[jgue467]

A little audio recording might help. Could be a loose belt, worn belt, try the soap method to quiet it down to isolate the belt.

I think it's something simple, not the towing out so much stressing it, they're pretty tough. Luck. :cowboy:

 

[Mutant]

A little audio recording might help.

You must have missed the YouTube link at the top of my post. It doesn't sound like a belt to me. That's why I'm worried.

 

[heat]

Sounds like it could be a vibrating or scraping heat shield. If it's on the
exhaust, it might get hot enough in a few seconds to stop making noise.

 

[Mutant]

After more research, I think it is dry starting. Excess sludge is blocking oil from reaching certain internal components, causing the dry start (metal on metal scraping). After the truck is started cold, it takes several seconds for oil to reach the dry area. I'm changing oil now and experimenting with Lucas Oil Additive that claims to "prevent dry starts". I'll try to post results in next couple days.

 

[nwh5024]

Sounds to me like the AC idler pulley. They have issues often after "mudding" and being in deep water. Even when AC is not engaged that idler pulley is spinning.

 

[pluton]

Your next task is to locate the noise. An automotive stethoscope is not expensive. Also, heavy mudding and daily driver don't completely go together in my mind....but don't listen to me, there's no mud near where I live...everything's dried out.

 

[Mutant]

Your next task is to locate the noise. An automotive stethoscope is not expensive. Also, heavy mudding and daily driver don't completely go together in my mind....but don't listen to me, there's no mud near where I live...everything's dried out.

Mudding is often part of my job. It was necessary not recreational.

 

[Mutant]

Update: changed oil with conventional and added Lucas additive. Next day no change. Sound may be getting a little worse.

 

[kolelt]

Your next task is to locate the noise. An automotive stethoscope is not expensive. Also, heavy mudding and daily driver don't completely go together in my mind....but don't listen to me, there's no mud near where I live...everything's dried out.

You could use a screwdriver. Place it on what you think it is. And put your ear on the handle.

 

[Mutant]

UPDATE:
BRAKES!!
Its components in the master cylinder making this noise. The sound was echoing off the block and made me think it was inside. A few weeks ago I had brake line extensions put on and bled by a local brake shop. They must have caused a leak somewhere. Fluid was very low. Probably air inside system. This morning dash brake and ABS lights were going off like crazy with a beeping alarm.
After I researched this for several hours, I found that 01 and 02 4runners along with some Land Cruisers have this crazy SUPER EXPENSIVE master cylinder assembly. The system is sensitive to any air getting in lines. That or low fluid may cause the Accumulator to vibrate and heat up, the pump below it will scream like a banshee.
If you google land cruiser brake screech you will find video of the same exact sound I posted up top. I took the truck back to the guys who did the brake lines for them to fix it. I have my fingers crossed and am hoping to god that it is only a leak in a line because if its a bad component in the Master Assembly then my truck is totaled. That fix will be around $3000 for those crazy complicated parts.