864running

Truck makes a gnarly tea kettle whistle noise from what seems to be passenger side of the engine bay, no vacuum leaks it was ran on a smoke machine and couldn’t find Jack. Exhaust is all bolted up right throughout the whole thing. Runs fine, doesn’t overheat but whistles loud after hitting temperature. It doesn’t do it on initial start which is really weird. Any ideas?

scope103

You've got an engine bay, but what engine is in it? [Put your make/model/year/engine/trans/trim in your signature. We won't have to keep asking.]

Assuming you have the 3VZE: PAIR valve, EGR Modulator, EGR valve, Gas Filter (not fuel filter), fuel pressure-up, A/C idle-up, PS pump ....

My ear is about 250 miles farther from your engine than yours is. Get the tube from inside a roll of paper towels (or the hose from a vacuum cleaner, or a piece of larger-diameter fuel hose ....) to use as a wide-area stethoscope. This should help you to narrow it down to a single point.

864running

lol, rookie move on my part. It's an 86 4R 22RE. and believe me, I have used a stethoscope along with running without belts to any pulley to see if it was a pulley making the noise. It's not a belt screech or pulley squeal its really like a vacuum whistle almost but I've plugged or squeezed most if not all lines to see where it's coming from and nothing. Something that I can think would be if there's any valves or ports that only draw vacuum at idle. the second any gas is applied the whistle goes away whether its parked or driving.