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Discussion Starter #1
Took my buddy for a ride in my car tonight and on a pull I thought I lost a rocker arm, I had a stud pull out last fall on an old set of highports. It's probably had 50 pulls on it since then with no issues.
Anyway I nursed it home about a half a mile and pulled the valve covers and to my surprise didn't see an issue. Rockers are all tight, studs are bottomed into the guide plates, so I started it up and at idle it's quiet, tap the gas and it rattles. I pulled the plugs and cranked it around and checked each rocker for a collapsed lifter and they appear to be good. Plugs all look good, IAT's were fine and looking back at the logs from the fall, there's no change in average oil pressure's. Is it possible to spin a rod bearing and not loose SOME oil pressure? I'm at a loss here.
 

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Of course not, visualize 'how' rods work. Oil pressure normally squishes out the sides of the rod bearing. Many times if you have one that spins, it will plug the oil hole at least part of the time. Unless you pound the bearing shell clear to pieces----in which case it knocks, you will likely have MORE if measurable, not less

And the oil pump has enough capacity that just one rod probably is not gonna show up

I've lost two rods, in my lifetime, in just that way. Neither one made noise, seemed to increase in temp. It was more WTF? Is this thing a little low on power? Yes? No?
 

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Discussion Starter #3
Doesn't seem to be down on power or at least not to the point my butt could feel the difference. The datalog did show that it quit pulling rpm's after the 3rd gear shift.
I also wouldn't assume it to be a rod bearing but I've checked the things that made the most sense.

 

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Discussion Starter #5
Cut the filter. You will know right away.
I pulled the filter and didn't notice any shimmer in the oil contained in it but I'll cut it open tomorrow. I don't have a filter cutter, so I'll have to snip it open.

Anything else come to mind? I may pull the intake tomorrow and have a look at the link bar lifters.
 

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Discussion Starter #6
Filter looks good, no idea what's going on here. Noise sounds like it's in the top end but visual inspection looks great.
 

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Check the flywheel to see if it's cracked or if the converter bolts got loose.

If thats not it check the accy drive for something loose.
Will
 

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Discussion Starter #9 (Edited)
Check the flywheel to see if it's cracked or if the converter bolts got loose.

If thats not it check the accy drive for something loose.
Will
Both of those checked out fine, bolts all in tact and tight, no cracks in flywheel that I could see. I'm only running an alt. It still has 60psi of oil pressure during cranking.

I've got a buddy coming over this week to start the car while I have the V/C's off so I can see the valve train while it's running rather than cranking it with my remote button to the solenoid.
 

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Discussion Starter #10
Found out it wasn't a bearing after all. First time I've experienced this but I lost a chunk of a piston. Sounded exactly like a rod knocking, lol. I can't for the life of me figure out what happened. Boost was low (9#'s), AFR was safe (11.5:1) on pump 93, timing was safe and I was spraying water/meth on top of it all.
 

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Found out it wasn't a bearing after all. First time I've experienced this but I lost a chunk of a piston. Sounded exactly like a rod knocking, lol. I can't for the life of me figure out what happened. Boost was low (9#'s), AFR was safe (11.5:1) on pump 93, timing was safe and I was spraying water/meth on top of it all.


then it should have been metal in the filter.......... hate that for ya man..
 

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Discussion Starter #12
then it should have been metal in the filter.......... hate that for ya man..
Thanks, it was my first time cutting a filter open and looking for anything. In my mind I was looking for copper and missed some of the more obvious crap in the folds of the filter.

At least a portion of it stayed in the cylinder.


 

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None of that should have made it below the rings to get in the filter. It looks like the intake valve tagged the piston, it might be bent, or maybe it is a reflection??? Look for pieces of piston to have gone into other cylinders.
 
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