Spouse called me from parking lot half way home this afternoon while driving the brick. Car had started making an "alarming noise" so she pulled over. Drove out to meet her, restarted car. Transmission still in park. Horrendous squeely kind of noise from somewhere in front. Followed her home making a big spectacle of myself. Hard to say for sure, but transmission seemed to be shifting normally and don't think revs were exessively high for roadspeed (so, don't think it was slipping).
Parked in garage and popped hood. Seemed like noise was coming from front end, like a bad belt or pump. Shut her off, scratched my head. Restarted and....no noise, car behaving perfectly normally. Tried spraying water over the belts, AC compressor, alternator etc to see if I could get it to do anything. No "luck".
so, real puzzled as to what was going on.
Any ideas? Hard to troubleshoot when it won't do it again.
Warm, dry weather here. AC was on when it first happened, but I had it switched off as I drove home.
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Current: '95 945, 128K miles; '90 BMW 325i, 109k miles. Former Volvos, gone but not forgotten '85 245, 250k miles; '91 744T, 150k miles

I am going with the Harmonic Balancer theory for time being. Painted a continous white-out line across face of balancer and out to outer diameter a few days ago. The lines are still all lined up and the noise has not repeated itself. Will re-post when/if I get this figured out.
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Current: '95 945, 128K miles; '90 BMW 325i, 109k miles. Former Volvos, gone but not forgotten '85 245, 250k miles; '91 744T, 150k miles

The harmonic balancer is bad. The rubber bond has come loose and the slipping between the rubber and metal causes the squealing.
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john

Thanks for responses.
Mystery deepens. The loud alarming screetch has not repeated. But, under heavy acceleration it will make a not excessively loud metallic clattering sound for a few seconds, like a hamster-wheel in operation or a can-lid bouncing on something. Coincidence? or somehow related?
No visible sign of alternator being out of alignment nor distress on alternator belt. Will have to inspect balancer to see if it looks suspect..
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Current: '95 945, 128K miles; '90 BMW 325i, 109k miles. Former Volvos, gone but not forgotten '85 245, 250k miles; '91 744T, 150k miles

Dear Turbine1,

Hope you're well. The easiest way to assess the harmonic balancer: take a bottle of white-out (or some white paint). Starting in the center of the pulley, next to the crankshaft bolt, draw a line straight out towards the front of the car. When you get to the pulley face, continue the line towards the ground, across the face of the pulley.

Drive the car. If afterwards, the line is as you drew it, the harmonic balancer is fine. If the line has separated into two segments, e.g., one is at 6 o'clock and the other is at 3 o'clock, the harmonic balancer must be replaced. The reason: the rubber section has failed, and no longer connects the crankshaft-mounted core with the belt-carrying surfaces.

See the FAQs for the procedures to remove/replace the harmonic balancer.

Hope this helps.

Yours faithfully,

Spook

Thanks Spook. Nice to hear from you again. Been a while since I posted here. Good tip. I will try that.
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Current: '95 945, 128K miles; '90 BMW 325i, 109k miles. Former Volvos, gone but not forgotten '85 245, 250k miles; '91 744T, 150k miles

See if the harmonic balancer (crank pulley) is red hot after the noise is heard. If the inner and outer sections are slipping you get a screech and heat. Visual inspection of the rubber mid section is also informative.

Sorry I should have added remove the serpentine belt and start it and see if the noise goes away. If it's the starter pinion it won't. If it's the idler pulley it wlll. Spin the idler pulley with the belt removed if it makes any noise the bearing is bad.

Check to see if the Pulley is cocked a bit on the Alternator, What happens is the rubber bushings wear out on the Alternator mount ( power steering and AC too but mostly the Alternator) and causes the Pulley to be slightly scewed in it's relationship with the Water pump pulley. Look down teh Water pump pulley at the Alternator pulley and yo umay notice the Alternator pulley is not absolutely in Parallel. The Belts will squeal like hell until the belt warms up then, sometime, it quiets up.
Teh water trick works the other way around. When the belt is squealing, spray teh belts to see if it gets quiet.
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'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The '89 Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me http://home.no.net/ebrox/Tony's%20cars.htm

Hi,


Refit the engine with new belts. Conitech is preferred, as the fan belts are a matched set.


Goatman

My 960 started doing the same thing yesterday. Tried multiple starts and wouldn't repeat.... Until my wife drove it to work today. All the way there and back. I believe its the starter pinion not fully retracting into the housing, the loud screeching is the noise you get when it rubs the flexplate. I'll pull the starter and let you know.

Did you guys ever find the solution to this problem. I have a similar one, and am also suspecting the starter.