Friend bought a 1992 240 ~200K miles. Had been sitting ~ 1.5 years; PO said that a mechanic said “something might be wrong with the alternator”

1. The belts squealed. I replaced with matching used Volvo belts and replaced the brushes - the old ones were OK, not great. Alignment was fine, bushings tight. Squeal continued: at high idle, under acceleration.

2. Replaced the alternator pulley and replaced the belts with new. Seemed better for a while, then squeal started again.

3. Replaced the alternator and battery. Still squeals.

4. 3rd alternator, still squeals. It quits after 10 minutes of driving.

It's not the damper or the a sticking water pump. Belts are tight and not frayed. Nothing is rubbing. Alternator bushings are new and alignment is true.

Could be that I have the wrong belts and they aren't making good contact. Or a wrong pulley on the water pump. Otherwise I've no idea.

One odd thing: was driving the car (between items 2 & 3 above. The squeal quit and the instrument warning lights came on. Limped home. Brushes were fine.

Excite wire tested for ground but between the grey firewall connector and the dash (with the plug removed from the cluster), not between the connector and alternator - this is a 1st for me. I also had continuity both ways. I replaced the wire between the connector and the cluster and the instrument lights went out.

It's possible that alternator #2 failed internally and somehow fried the wire.
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240 drivers / parts cars - JH, Ohio