Engine makes a knock at light throttle when it warms up a little, makes the noise when you are not really on the gas and not really off. 69K miles on the motor, allways run mobil1 and pure1 filters.
This noise started after a 6K RPM trip up the on ramp.

I have pulled the belt to see if its any of the accesories and the noise is still there. I pulled both valve covers and everything is intact and not loose.

I tried using some thicker oil (3 quarts f 20W40 and 2 of SAE 60W), and the noise got a little quieter.

When I dropped the oil, it was a little silverish, but not really bad as I have seen in some pics where people have spun bearings. I ripped the filter open, and if I dig in the crevices of the filter, there is some gunk (silverish black) in that. Around 3K on this oil/filter.

Does everything point to bearing issues, and thus a rebuild? I don't want to have it be something simple. Actually, it would be nice if it was simple.

 

almost sounds like a lifter. I would try a new set of lifters and if that doesnt do it then YES it will need a rebuild

Matt

 

Hmm, any way to check the lifters without pulling the intake?

 

I took a real close look at my valvetrain with the engine running and off, and everything appears good up there, no broken springs or loose rockers, all rockers/valves move the same amount, and its generally pretty quiet up there. All my header bolts are snug, and I cannot feel any leaks.


Well, I tried the infamous screwdriver test and here are the results.

Screwdriver on either side valve cover bolt-light tapping
Screwdriver on either side head or intake- Clacks allmost like a diesel engine would

UNDER CAR
Screwdriver on oil pan/pan bolts- light tapping
screwdriver on bellhousing(t-56)-HOLY COW, pretty loud tapping


Its strange that it will make the noise in any gear with the clutch engaged or not. It is not real noticible at idle, and not at all when the engine is cold. Once it warms up a little though is when the noise starts, and when the engine is fully warm it gets louder.

I'm racking my brain here...PLEASE be something stupid!

 

Also, car seems to run just fine, no missing or stumbling, and the Oil pressure is normal as ever....

 

can you apply the parking brake and power brake it slightly , to see if the noise changes.
try letting it rev around 2000 rpm in neutral and slightly give a little more and less throttle, check for changes in the noise, let me know

but from what you said here....

Engine makes a knock at light throttle when it warms up a little, makes the noise when you are not really on the gas and not really off.


really sounds like a rod bearing

 

I'll try that right now...BRB

 

Noise stays pretty much the same when I PB a little, 2K rpms seems to be when it all starts. And yes, its does not do it under load or coast, just when light throttle is applied. Bummer.

 

I had a bad lifter, Here you you can look for:

http://adamshipley.com/camaroz28/lifter1.jpg
http://adamshipley.com/camaroz28/cam.jpg

Heres a vid of what my car sounds like with a bad lifter
Heres another vid

I have noise basicly 2k and under, it was quiet past 2k rpm.

 

Dang that really chewed your cam up! Did the roller part sieze up or?
I'm guessing it did not run well with that in there, mine runs perfect still, well other than the noise

 

Acually it ran really strong, I thought it was a minor problem because I had no noticable power loss, but a tap tap tap at idle. The roller was still fully and easily rolling. My oil pan was full of grit that felt like sand.

But what caused all this in the first place was one WOT. I was unaware that the filter fell of my newly installed K&N cai.

 

when you float the rpm a little above and below around 2000 rpm is when i can pick out a slight rod bearing knock,if it doesn't do it under a load or coast only, i would rule out lifters, did you have the flywheel off lately for a clutch replacement, loose bolts on the flywheel maybe

 

YOu describe my car pretty good, looks like she is coming out this weekend.

 

i'm pulling mine too in a day or two, to put the cam ,stall,headers and a few others on it, but it's going to the track first

 

UPDATE: It was the #1 Rod bearing. Got the pan off, and started at the rear of the motor (sounded louder back there). One by one I pulled rods/pistons, and they all looked decent, not spun or gouged, just small grooves. I was starting to wonder WTF, then the last one I pulled (#1), bearing was spun about 30*, and was missing some metal lol.

Oh well....bigger and better eh?