This new engine noise just started. Sometimes it's louder. Tends to (mostly) go away once I've warmed up and driven a bit. Sort of a belt-like squeal combined with a rattle. Some belt or pulley maybe?

Sounds like maybe it's coming from the alternator area, but I'm not sure. Honestly it's hard to describe, but a hundred miles ago the engine definitely started making a new sound and got louder, which is always a bit unsettling.

1992 toyota pickup, 4cyl 22re, 205k, 4wd, has A/C

 

take one belt off at a time and see if it goes away, just don't run it long without the water pump or the alternator. and turn the A/C on and off to see if it changes.

 

When was the last time you adjusted/tightened the belts? The do stretch over time. I have had to adjust a new alternator belt twice in two years...about once a year it needed to be tightened.

 

After you make sure it's not just a loose belt, spray some WD40 on each pulley one at a time until the noise goes away to figure out if it's a pulley.

 

Keep driving. The chances it will self heal are pretty high. It's a Toyota.
If it falls off, you will know what to replace.



Do you also spray oil on brake pads if they squeal?

 

Yeah... don't do that.

 

It's been about 8 months. They all feel pretty snug.

 

I blew a head gasket not too long ago. I'm trying to play it a little safer these days as stay on top of everything.

Maybe it's just whining for attention and if I ignore it, it'll stop?

 

Yeah... Don't do that either.
Does the noise change if you turn the A/C on and off?
Is the noise gone if you remove all the belts? It'll start and run fine for a couple of minutes with NO belts on, so this is an easy test.
If the noise is still there you need to look deeper, likely the timing chain slapping on the inside of the timing cover which will eventually wear through and leave you stranded with an even larger repair cost.

 

Sounds the same with or without A/C. Haven’t tested without the belts yet.

Timing chain guides were replaced with metal ones by a reputable Toyota truck shop at 168k.

 

According to your first post you have gone about 40K since then, I wouldn't rule out the timing chain guides based on that, even if it was a "reputable shop", ˟˟˟˟ happens and things break.
If the noise is gone with all the belts removed put them back on ONE at a time and you will narrow your problem down, water pump, alternator, A/C compressor, P/S pump, fan clutch, tensioner pulley.
Wiggle all of them while the belts are off looking for play, spin what you can feeling for roughness, listen for growling or clicking.

 

Haha, pulley bearing, not the belt!