LT1-LT4 Modifications 1993-97 Gen II Small Block V8

Odd Engine noise

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Old 12-15-2016, 06:04 PM
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Default Odd Engine noise


Bought this car with a bad optispark, its done this as long as i've owned it. Seems to be louder at idle, Definitely gets quieter when its warmed up. It's an abnormal sound to me,not sure i've heard something like this that's as inconsistent as this. Seems like it's coming from near the firewall on the passenger side most.


Any suggestions on what it could be?
Old 12-16-2016, 10:54 AM
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IMO it's not good news. That "chirping" could be roller bearings near the end of their life. Drain the oil to see if there is any metal flake/glitter.
Old 12-16-2016, 05:05 PM
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Op

what you hear vs what we hear on a cell phone video posted on the internet...likely not the same.

While worst case could be bearings as noted it could be other things like failing RR trunion or tip (if you have RR), cracked flexplate (if auto car), etc, etc

checking your oil for metal flakes (glitter) is one thing I would do

Go buy a $4 stethoscope at Harbor Freight and probe around motor, each exhaust and on valve cover over each valve to see if you can isolate the source of the noise better
Old 12-17-2016, 06:20 AM
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Take the belt off and try again. Sometimes accessory noises can be ventriloquists.
Old 02-03-2017, 04:09 PM
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Ok, a long time later i've finally gotten time to work on it. I drained the oil and it had very very little glitter if any i didn't really see much at all. I pulled the inspection cover and didn't see anything wrong, pulled the passenger side ( where the noise sounds like it was coming from) valve cover and adjusted the valves and nothing seemed to effect the noise. I'm not sure where to go from here
Old 02-03-2017, 04:23 PM
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You shouldn't have any glitter in your oil. Where you need to go next is to pull off the intake and look at the roller bearings on your lifters and cam lobes.
Old 02-03-2017, 06:00 PM
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Originally Posted by SS RRR
You shouldn't have any glitter in your oil. Where you need to go next is to pull off the intake and look at the roller bearings on your lifters and cam lobes.
I thought i would hear a change in sound as i messed with the problem valve? I guess that's what i was thinking. Hopefully its obvious once i get it off whats going on.
Old 02-03-2017, 08:24 PM
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I'm assuming you're talking about that light knocking noise? If so, the rate of it sound pretty rapid, that's usually a bottom end issue.

Like ****** said, get a $4 stethoscope from Harbor Freight and probe around. When you get close to the source of the noise it will get noticeably louder.

I had something similar on my 1995 Suburban. It turned out to be a completely broken fly wheel. I couldn't see it and happened upon it while under the truck trying find the source of the knocking (which kept getting worse everyday). I thought it was a low end rod knock, but turned out to be the flywheel. To check it, try and turn the flywheel back and forth. If it moves, without spinning the engine -even a little bit-, the flywheel is bad.








Old 04-21-2017, 02:29 PM
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Well, months later i've finally got time to investigate. Just got done pulling the lifters out of the passenger side and found this in the rear, next step inspect cam and go from there (i assume its probably trashed?)
Old 04-21-2017, 03:32 PM
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Yes, that noise can usually mean a major issue is happening. I have heard it myself and just got my engine rebuilt because of it. The reason it's a major issue is because the metal from that roller is hardened steel. When it flakes off it rains down on the piston skirt and can cause serious gouging in the skirts and cylinder walls. You can simply replace the rollers, drain the oil and such, but you may still be on borrowed time before you have a catastrophic failure. If you are thorough then rebuilding the engine is a must. Depending on the damage on the cylinder walls you may be able to get away with a hone and reuse the pistons, but this could also be an opportunity to bore it out for a 355 or stroker combination. Good luck.

P.S. Is that the only roller or are there more?

Last edited by SS RRR; 04-21-2017 at 05:50 PM.
Old 04-21-2017, 05:33 PM
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Third..

your cam lobe likely looks like the pic....been there.

with that much metal that went through the motor several bearings took a hit

I bought a forged 4 bolt 383 short block
Attached Thumbnails Odd Engine noise-7-cam-lobe-wipe.jpg  
Old 04-22-2017, 12:55 PM
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iPhone 7 picture? What great quality
Old 04-23-2017, 10:54 AM
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I think regardless i'm going to probably wait and see what the cam looks like and decide where to go from there, although i will plan on a rebuild. The roller on that lifter just looks like a pitted piece of metal in person in some spots and smooth on the other side of the roller, not as bad as the picture looks but either way i know its not good to have any metal at all going through the engine. I haven't gotten the driver side lifters out yet but i don't think they'll be bad *knock on wood*.

That's actually a somewhat out of focus picture from a dslr with a slow shutter that wasn't steady, thats why its kind of blurry

Last edited by Thirdgens88; 04-23-2017 at 11:06 AM.



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