Strange Noise, Ideas??

[Diabolic]

I have a friend that has a 331 stroker. It had almost 40,000 miles on it and started making a loud, very loud, sound from the front of the engine. The best way I can describe this sound is the noise a brake rotor makes on a lathe if you don't put that rubber ring around the outside. It's a piercing howl. I thought it was a pulley bearing first so I removed the belt but to my surprise the noise was still there. It sounds like it comes from the wp area. I laid on my back with the car running and probed around with a stethescope. The noise is the loudest right at the top of the balancer. This noise comes and goes at random. I drove the car 20 miles and it never made the noise then all of a sudden in the driveway it starts to howl. It will make the howl for 30 seconds then stop for several minutes. The sound almost has a pulsing rythm to it but it's a constant noise.

I replaced the distributor thinking it was a bad bearing but that did not alleviate the sound. The car runs perfect, oil pressure at idle is 50, and I'm completely stumped. I even thought perhaps it was the throw out bearing and the noise was traveling, but it doesn't change the sound at all when you push in the clutch. It's definately loudest in front. Everyone that hears it thinks its a bad belt or accessory bearing, then I tell them it does it with the belt off and they are stumped. Ideas??

[Diabolic]

What noise would a cam bearing make? Would a bearing create a noise that comes and goes randomly? If a cam bolt backed out of the timing geat and scraped the inside of the timing cover would it make a noise like that, and would it come and go? Maybe the cam dowel pin had backed out a little and is hitting the cover? Seems to me a bearing would be constant. Just thinking outloud here.

[shumpertdavid]

possible a cam thrust plate issue? You may end up having to pull the timing cover to look for the issue. Hope that there is a visible sign of something going on. I can't imagine any type of a bearing problem would go very long before bearing damage would give a more noticeable issue.

[dumpycapri85]

You probably already looked Charles but did you look at the timing pointer ? I have had them rub the balancer and make that kind of noise . If not I vote pull the cover .

[Diabolic]

it's actually funny you mention that because I discovered yesterday that the balancer wasn't pushed in all the way. I snugged it up another 1/8". It had a rub maerk where the balancer was rubbing the wp bolt. I thought that had to be it. He drove off happy , but came back in 10 mins with the noise. I was floored.