valves tend to tick not squeak. It sounds as though you may have a different problem here to me. If I had to guess I'd say it is either a smog pump or alternator issue. My smog pump made some interesting squeaky noises before I took it off. With all the alts I've had die, they sound like sort of a combo between squeak and grind. Both tend to sound worse at idle than at higher rpms.
You should be able to get the belt off just the smog pump and leave the others on, you could try that and see it that makes any difference. You could get all the belts off and try spinning the alt and the smog pump by hand and listen for noise too. They should be fairly quiet just spun by hand unless something is wrong.
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95 Isuzu Trooper Daily Driver
86 Isuzu Trooper reliable backup
77 LUV 2wd stock beltway blaster (resting)
79 4x4 LUV project: 2.6L, 5spd, 31s (eventually)
MEPR: Man, my 4x4 makes all other LUVs look good
