Elusive whirring sound

[rlux4]

Well, as talked about in another thread, I have a strange whirring sound coming from somewhere around the engine. Alvon and I put a new tensioner bearing and timing belt on yesterday, they were needed, but didn't elliminate the sound. This morning I took off the v-belt to see if the sound dissapeared without the aternator and water pump turning. Nope. The sound is still there. At this point I am starting to think it's something internal to the engine. But this sound is more like ball bearing noise and I've never had one of these engines apart, so I wouldn't know what's in there that could be the culprit. I know that without hearing the sound you all probably couldn't diagnose it, but maybe someone has had this experience and might have a clue for me. You know, me being clueless and all.
After having probably one of the most experienced Fiat mechanics (Mark) and then Alvon, who's been around these since I was a toddler (slight exaggeration) listen to it and saying they'd never heard it before, I may be stuck with it until whenever I have to rebuild the engine. With only 88M miles on her, I hope that's a ways in the future.
Ron

[ventura ace]

Gear noise in the Oil Pump maybe??? Or the gear between the aux shaft and the oil pump shaft???? Is that aux shaft pulley made from plastic? If yes, maybe the plastic cam wheel emits the whirring noise as the timing belt rolls through the grooves. I have a metal cam wheel that you can try. This noise is unlike any possible noise from a journal bearing. It has a beat frequency to it, that could be caused by teeth on a gear or a pulley, not like the whining noise of a bad journal bearing.

Alvon

[So Cal Mark]

I don't remember listening to it. Does it speed up with engine speed? I've heard t-belts sort of "zing" when they're too tight

[rlux4]

Man Mark, you must be getting old! Wait a minute, you're younger than I am. When I was down to get the vacuum advance from you a couple weeks ago, not only did I borrow your crows foot & rachet, I drug you out to the parking lot with your stethoscope to try to locate this sound.
Pope, you may be on the right track, we're pretty sure pulley is plastic, and Alvon had suggested changing it out for a metal one he had, but I'd already taken a good chunk out of his Saturday so I declined. And, it may be coming from the area of the oil pump. Good call, I'll look into it.
Thanks guys,
Ron

EDIT:
Oops, brain freeze here Alvon, sorry. I think I glanced at your avatar and saw Pope's. Man, I know I'm getting old. You did suggest the metal one while I was there.

[ga.spyder]

Ron ,that was my post last year with the mystery sound.I had a mech. w/ 35 years in Fiats say''Wow ,I've never heard that before''.I wish I could tell you what it was ,but it just stopped!I dumped the oil and there was some metal in there ,so it was internal.We did change the t-belt and tensioner bearing but the noise was still there.It was also suggested that it could be oil pump.My noise was originating in the top of the motor ,toward the rear.Could the flywheel be rubbing the shield on the bottom? I can only hope yours heals itself like mine.I was sure I was facing a rebuild.
Good Luck ,Craig

[rlux4]

We did check that the shield wasn't rubbing anything Craig. I think I'm leaning toward the oil pump being the culprit. Seeing as we eliminated the alternator and water pump as suspects, I think I'll let it go for now and keep a close eye on the gauges. Problem is, she's running so well I hate to stop driving long enough to drop the pan.
Ron

[ga.spyder]

I feel your frustration!Mine was showing no signs of anything being wrong ,except the noise.Does it do it all the time?Mine would do it for a few minutes then stop,and then it stopped completely.I was convinced it was the oil pump or worse(a bearing?)She hasn't made a sound since ,and seems to show no ill effects.
good luck ,Craig

[rlux4]

Pretty much all the time. It does seem to be more pronounced at start up and eventually get quieter. It never does go away though.
Ron