onspeed

Developed out of the blue while I was driving yesterday, thought it was belt noise at first. Speeds up/slows down with engine RPM. Persists after removing both belts. Sounded a little louder on the driver side, but didn't really seem like it was coming from under the valve cover although I haven't yet taken a look under the valve covers. Doesn't sound like a rod knock or lifter tap either. No noticeable issue with the car, not misfiring, hesitating, etc. Oil level is full and good pressure. Ideas?

Smoken1

Hard to tell from the short vid. Are you still using the stock balancer?

onspeed

Negative. Stock sized powerbond pulley. Almost new. I think a lifter or two might have **** the bed based on some other videos I've found with similar sounds.

Rob 02

You may have spun a bearing. Was there ever an over-rev during down shift?

Secondly does it do it regardless if the clutch is engaged or not?


Don't drive the car or run it unnecessarily. Get a mechanics stethoscope. They are not expensive. probe the area for where the noise is strongest.

Check the oil for stripper glitter. Bearing babbitt is non magnetic.

pewter99

my thoughts...

when my wifes 02 spun a bearing it was fine for awhile....

onspeed

Clutch engagement doesn't alter anything. Couldn't really isolate the sound anywhere with a stethoscope. seemed maybe little louder on rearmost cylinders on the driver side.

Never missed a shift or overrev the car before. Going to drop the car off tomorrow to have it torn down. Will keep the thread updated with the results. Fingers crossed I'll just be needing new lifter and cam.

drtyTshrt

I could not see the video while at work.
Does it sound like this?
WHEHWHEHWHEH HWHEHWHEHEHWHE WHEHWHEHW HEHWHEHHWHEH
or
wha hwa hwah wha hwa hwha hwhhwahwhah whah ewha

Rob 02

It is tell tail of a spun main bring.

Perhaps not what you want to hear but it may be the truth.

onspeed

Maybe so. Seems like people have found spun bears or bad lifters making similar noises. I figure it makes sense to take the heads off and inspect the lifters and cam lobes and go from there.

Rob 02

A spun bearing squeaks and gets worse.
If you run it longer you will burn the bearing journals on the crank shaft.

Do you have any idea of how many times I have seen this?

Rob 02

The parts in the valve train don't rotate but reciprocate. They do it at a certain frequency.

Since you are an expert maybe teach us a few things.

onspeed

How many times have you seen this?

https://ls1tech.com/forums/generatio...ad-lifter.html

https://ls1tech.com/forums/generatio...ing-noise.html

Two of many examples of similar noises that ends up being a lifter/cam issue.

Never claimed to be an expert, just makes sense to pull heads before pulling the motor. Thank you for your input though.

onspeed

Apparently bad cam.

Rob 02

Is that the cause or the effect?

I worked as an engineer since the early 90's.

onspeed

Suspect it was a bad cam core. Was 3 damaged lobe all together, the worse one pictured. New lifters and cam and car seems back to normal now. Old cam was a comp grind, custom spec from PatG with EPS lobes. Replaced it with a Torquer v4 from texas speed.

foggy

Thank you for the follow up/ Feedback on the results
IT's very important for those of us following that are eager to always
learn more !

grasshopper645

I wish I had the funds to do an engine tear down every time i heard a strange noise