Topic: 22RE high pitched noise/intermittent at idle

[Rivergoat]

'K...here's one a number of local guys could not isolate. Only at idle a high pitched noise will come on; not belt related. It does not sound pulley related, but I can't totally rule that out. Stethoscope can't even isolate. One moment sounding like near the front/fan area, then more towards the rear. At one point loading with electrical makes it come on, and at other times turn on all electric and nothing. Creating a vacuum leak (pulling PCV hose) has been fairly consistent in getting it to come on, but it seems like a low idle is the main thing that triggers it. It can stop on its own, as well as not come on at idle at all.

Recently during some maintenance I have replaced valve cover gasket, half moons, PCV grommet, PCV valve, PCV hoses, small vacuum hoses (there's one or two yet to do when I can get better access. Air hoses from resonator are about to be replaced.

After I did all the hose replacement (oh, and also the distributor o-ring), and did the vacuum lines one at a time so as to not cross anything, when I fired it up it ran very rough. After a long period of trying to isolate that, it was when I disconnected the vacuum line from the 3 port VSV (part number 90910-12085) that the engine ran smooth as could be. Testing leads me to believe that VSV is toast; I plugged the lines for now, and found a VSV on line that is shipping to me. But for the moment it runs great, yet the noise will reappear. One guy said alternator, another water pump, another pulley, another vacuum leak. Everyone has an opinion, nothing has cured it.

A benign sound isn't that big of a deal, but planning on getting into the desert soon, and don't want to have something catastrophic fail that I could have fixed/prevented.

While it idles and runs fine with the VSV bypassed, I was thinking of at least spraying the vacuum ports into the throttle body. Symptom of the noise is not consistent with a dirty throttle body (no rough running/poor mileage) nor alternator (good charging, no light dimming, and certainly no CEL). And with no CEL, also no reason at the moment to overly suspect EGR valve...but???

Without going on and on much longer...any thoughts on where next to check?

[Axman]

These are the things that make you hate mechanics 
Try checking the brake booster. Mine once had a similar problem that was caused by a pinhole leak in the brake booster, so under a vacuum the air would whistle through the hole making a high pitched noise. but unlike yours, you could hear it whenever the truck was running. Thats my 
it might be worth checking out on yours.

[Rivergoat [OP]]

Reasonable. I haven't changed the brake booster lines (yet). I'll examine them soon and see what's up.

All the parts I've bought so far are well worth doing. I had not been making much $$$, and a recent job change provided a needed raise to get to some sorely needed maintenance. Already spent about $250 in various parts. Some of the high temp hoses are way pricey (and the dealer charged $19/each for the half moons...where else am I gonna find those new, eh?)

Anyhow, I'll add the booster to checking soon, thanks. Anyone else with a thought is welcome to chime in.

FWIW...this is a '94 22RE with 236K on the clock.