Screeching

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Ironmike

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Boy I hate these kinds of posts but thought I'd throw it out there.

2 seasons now, recently got louder. I have this screeching, ringing type noise.NOT always there. Only comes on around 2100 RPM, then again around 2900. Seems worse once warmed up. We seem to feel like it's coming from the rear underside of Engine. Very hard to duplicate in the garage. Easily heard cruising down the road. Clutch in clutch out doesn't matter.


Not: alternator, waterpump, pilot bearing, fan belt.

I have a Qtime scattershield with block plate and a hydraulic throw out bearing. Just had the bearing out, it seems fine. No marks on the block plate or shield. I thought it might be some weird harmonic exhaust pipe ringing thing. But darn if I ain't stumped.

Had distrib out today, it and intermediate shaft bushing look ok. Car runs great as usual, but this is becoming annoying.

Thought about thrust bearing for a minute......or a lifter roller.......any guesses might point me to it.
Weird.
 
Would you be able to post a video? Have you been able to jack up the rear end and run it? Dangerous method so take precautions to make it safer.
 
What are you using to probe with? A length of fuel, etc hose up to your ear works pretty good
 
Would you be able to post a video? Have you been able to jack up the rear end and run it? Dangerous method so take precautions to make it safer.
I can't figure how to post videos on this site. Yep jacked it up in the garage and duplicated the noise. Sounds rotational for sure.....sort of an odd ringing....
 
Were you able to put a load on the eng during the jacked up run by using the brakes to see if it's louder and more define? I like to use 1" or larger pvc pipe to find noises. If you can isolate it to an area, tear it down and change/inspect every component. If you can't find anything, it'll surface when it wears out enough and the problem will find you.
 
I can't figure how to post videos on this site. Yep jacked it up in the garage and duplicated the noise. Sounds rotational for sure.....sort of an odd ringing....

You have to have them on youtube, then post a link here...
 
This reminds me of one from way back. That member finally found the front crank seal to be his squealer/noise maker. That might have been a slant 6 though.
A long tube funnel like a trans funnel makes a good listening stethoscope. Localized at one end and amplified at the other.
 
Stethoscope, listen to header tubes to isolate in that area, try wood shims between tube and a short test run.

Could very well be a solid roller squeal, or maybe something dumb like a pcv valve buzzing, assuming you still run one.
Fingers crossed that it's nothing major.

What spring pressures?
 
No pvc. I believe this engine's springs are 605 open, .650 lift. I believe. Been awhile.
 
oil slinger ? Mine did same thing but I would think you could tell it was in front of engine.
After market Dampner had a little shorter snout and would not snug up against the slinger.
Would ring and rattle and scrape at various RPMs.
 
Could be just harmonics too. Try wood blocks wedged between the header tubes like Official said. Do you have a wind age tray in there?
 
Watch the balancer for excessive motion fore and aft as you rev the engine. Check your balancer for slip while your at it.
 
oil slinger ? Mine did same thing but I would think you could tell it was in front of engine.
After market Dampner had a little shorter snout and would not snug up against the slinger.
Would ring and rattle and scrape at various RPMs.
Ya know I actually thought about the oil slinger. I remember it was pretty close to that Cloyes chain.....
You'd think it would eventually stop rather than get worse, though......... I think.
 
Could be just harmonics too. Try wood blocks wedged between the header tubes like Official said. Do you have a wind age tray in there?
No tray. Will try some blocks. Plan to get it up on the jackstands tomorrow.
 
I doubt it has anything to do with the oil slinger. The oil pump drive is helical cut and this applies constant thrust on the cam. So unless the slinger itself is loose, it would be a constant noise. The crank is constantly thrusting forward from the pressure plate of the transmission. And it happens clutch in/out.

It is also strange that it happens at 2 different rpms. I would bet it is harmonics in this case, and that the tones are slightly different. A permanent solution if it's the exhaust is to use header wrap and band clamps.

A galled roller lifter bearing is plausible but I wouldn't think that it would last too long.

Are you able to vent the exhaust out the garage and close the door to make it quieter?
 
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You may also want to make a timing adjustment (retard it significantly) to see if the rpm it occurs at and/or tone changes. If they do don't worry about the noise.
 
Since nodoby else said it... Just kick this guy out of your car!
the-bell-won-t-save-him-now-dustin-diamond-sees-life-screech-to-a-halt-as-he-s-sentenced-476248.jpg
 
I.M. If it's chirping I was using some valves that had a sort of fish scaling on the stems. Supposededly for oil retention. Every time I used them, they would chirp. Drove me nuts. But I've never seen a valve like that fail. IDK if you can get them any more. And, I never saw them for a Chrysler.

I did have some engines that would chirp with a 50* seat. I have a long haired engineering friend who came by the shop and looked everything over. He claims it was because air passing the exhaust seat under those high pressures with that steep seat caused it.

Then he wrote out some long equation and said the math says he's correct. I have no idea, but I use a 50* seat on my engine and it doesn't chirp.

Short answer...I'm just throwing stuff on the wall to see if it will stick.
 
Does this noise come when it is accelerating, steady speed, decelerating, downhill, uphill or when?
 
I had a screeching in my Dart that was hard to pin point. Turned out it was a spring in the drum brakes rolling around.
 
All of the above.
Sounds like something just vibrating and fixed to the engine or body, with the RPM's exciting it, almost sounds like a heat shield on a modern exhaust that gets loose. Maybe the oil pickup vibrating against the pan, or a windage tray vibrating? How heavy is the metal on the scattershield's block plate?
 
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