Throwing this out there for opinions.

[turbov6joe]

My dad's new motor has maybe 1500 street miles and about 15 WOT passes since its rebuild....it's basically a girdled 109 block with OE rods, roller cam, forged pistons, ARP everything, and a 10/10 crank. Just recently he was driving back to his house and noticed his scanmaster was showing knock retard (KR) in the area of 8-14 degrees whenever he was off idle....however his audible knock detector was not going off at all. Anyhow we put the car on stands and noticed that when we reved up the motor we could here an audible metalic knocking sound...kinda like something was loose but NOT like a deep rod knock. AT idle the motor is as quiet as could be and when using a mechanics scope we cannot hear anything out of the ordinary. Now, when we rev it up or blip the throttle at higher RPM's the sound is obvious and loud enough to hear from topside of the engine bay...kinda sounds like a rattle. AT first we thought the sound was coming from the rear of the motor but now think it's coming from the front I climbed under the car and watched the flexplate while my dad was reving the motor up and noticed that it seemed to be moving back and forth quite a bit...maybe 1/2". However, when we took the TC bolts out and pushed it all the way into the tranny we were NOT able to manually move the flexplate back and forth more then just a fuzz....so that kind of ruled out a thrust bearing for now. We also ran the motor with the TC disconnected...the sound is still there. We then took off the serp belt and the sound was still there. We checked for tightness on everthing we could get a wrench on to no avail. We pulled the oil filter off and cut it open to find a significant amount of copper colored metal in the filter's pleats...I'm guessing bearing material there.

Before we go and yank the motor out do any of you have an opinions as to what this sound is or where it could be coming from? Anyone think rod and/or main bearings? The motor is coming out no matter what, we're just looking for a place to direct our attention to.


TIA

 

[8UWITH6]

At least its cold out.......... let me know if you guys need any help okay?

 

[Phoneguy]

The copper color you are describing could very well be copper spray from the head gaskets. The rattle could be from the roller valve train. Mine is noisy and it makes you wonder. Good luck. Keep us posted
Bryan

 

[BlownV6]

Sounds like a bearing problem to me. What trans are you running?? Mike

 

[S2V6RACER]

It should not be knocking for starters, so you have to pull it out and inspect. You should not be able to see the minimum thrust play there while it is running so I think you have a problem in that area. It will be obvious when you pull the bottom end apart and check the bearings like Mike says.

You have done a good job trying to eliminate the other possibilities. Out it comes..

 

[turbov6joe]

Sounds like a bearing problem to me. What trans are you running?? Mike

200

 

[turbov6joe]

At least its cold out.......... let me know if you guys need any help okay?

10-4

 

[turbov6joe]

It should not be knocking for starters, so you have to pull it out and inspect. You should not be able to see the minimum thrust play there while it is running so I think you have a problem in that area. It will be obvious when you pull the bottom end apart and check the bearings like Mike says.

You have done a good job trying to eliminate the other possibilities. Out it comes..

About the only thing we have not checked are the adjustable rockers...
I've had mine come loose and I'm familiar with that sound...his car does not sound like that. The sound is so hard to explain in text...it's kinda between a deep knock and a light metalic rattle.

 

[qwic87gn]

Mine sound started off as a light mettalic tick and within a coule hundered miles was a loud rod knock. Had I tore into it when the sound first presented itself, I may have gotten away with just changing bearings. This was not on a fresh motor however... Be sure to rule out the valvetrain before you pull the motor. You may be lucky and find the problem there.

 

[gnxtc2]

First, the shop that did the rebuild, have they ever done a Turbo Buick motor?

How many oil changes did you guys do?

Did you inspect the flexplate for cracks?

What concerns me is the significant amount of copper in the oil.

What bearings are in the motor? If the engine builder put in the Super Duty Race Series bearings with a production crank, kiss the main bearings good buy.

Was the motor line honed with girdle in place and heads attached?

Billy T.
gnxtc2@aol.com

 

[turbov6joe]

The shop that did the machine work has done a few LC2's and is really good...the guy that owns the place does the work himself and is over anal.

The oil and filters have been changed numerous times since break in.

I believe the girdle was on it, the heads were not when the LB was done.

The flexplate was inspected best we could with the motor/tranny still attached.

The bearings are the HP Clevite 77's.

 

[ijames]

Pull the valve covers and make sure a rocker isn't hitting a cover, then pull the motor, sigh.

 

[bison]

First drain the oil and drop the pan since you suspect bearing failure. Crank end play should be .004. Not nearly enough to see if under the car pushing and pulling on the flex plate.

 

[gossamer]

If you can see the flexplate moving back and forth a 1/2 inch, it sounds like you smoked the thrust bearing. It would also explain all of the copper particles in the oil filter. As Bison said, you should have only a few thousandths end play in the crank. Check that #3 main bearing Check your flexplate for cracks too. If it's cracked, it will sound like a knock. Good luck

 

[Rodney87GN]

Your noises sounded like mine when I found my crank endplay at .018" After tearing it down I also found a wasted rod bearing. Make sure the balancer is tight on the crank. Then yank on the balancer back and forth to check crank endplay. Good luck, but I have a feeling you'll be pulling the motor soon.

 

[novaderrik]

if the thrust bearing is gone, you will be able to see the balancer moving back and forth as you rev it. i'd think it would also cause some problems with the crank sensor.
my brother's 90 Beretta with a quad 4 made a sound like you describe- it sounded more like a windage tray came loose and the crank was hitting it as it went by or soemthing like that than a rod knock. there was no sparkly stuff in the oil, and it ran fine. but it made that damn knoking sound, which causes the ecm to pull timing and make it run like crap.
one day, it was idling and i was sitting in the driver's seat listening for the noise. i gave it enough throttle to rev it up to about 1200rpm with the clutch in , and suddenly there was a "bang" sound, and the motor smoothed out and started running really good. my brother noticed steam coming out of the snow pile about 10 feet in front of the car, and pulled a large piece of the #2 connecting rod out of the snow bank.. except for the big hole in the block and oil pan, it ran better on 3 good cylinders with full timing and fuel than it did on 4 cylinders and less timing.

 

[turbov6joe]

if the thrust bearing is gone, you will be able to see the balancer moving back and forth as you rev it. i'd think it would also cause some problems with the crank sensor.
my brother's 90 Beretta with a quad 4 made a sound like you describe- it sounded more like a windage tray came loose and the crank was hitting it as it went by or soemthing like that than a rod knock. there was no sparkly stuff in the oil, and it ran fine. but it made that damn knoking sound, which causes the ecm to pull timing and make it run like crap.
one day, it was idling and i was sitting in the driver's seat listening for the noise. i gave it enough throttle to rev it up to about 1200rpm with the clutch in , and suddenly there was a "bang" sound, and the motor smoothed out and started running really good. my brother noticed steam coming out of the snow pile about 10 feet in front of the car, and pulled a large piece of the #2 connecting rod out of the snow bank.. except for the big hole in the block and oil pan, it ran better on 3 good cylinders with full timing and fuel than it did on 4 cylinders and less timing.

Dude, that story is near unbelievable. Good thing nobody was standing in the direction of the flying rod!

 

[bison]

if the thrust bearing is gone, you will be able to see the balancer moving back and forth as you rev it. i'd think it would also cause some problems with the crank sensor.
my brother's 90 Beretta with a quad 4 made a sound like you describe- it sounded more like a windage tray came loose and the crank was hitting it as it went by or soemthing like that than a rod knock. there was no sparkly stuff in the oil, and it ran fine. but it made that damn knoking sound, which causes the ecm to pull timing and make it run like crap.
one day, it was idling and i was sitting in the driver's seat listening for the noise. i gave it enough throttle to rev it up to about 1200rpm with the clutch in , and suddenly there was a "bang" sound, and the motor smoothed out and started running really good. my brother noticed steam coming out of the snow pile about 10 feet in front of the car, and pulled a large piece of the #2 connecting rod out of the snow bank.. except for the big hole in the block and oil pan, it ran better on 3 good cylinders with full timing and fuel than it did on 4 cylinders and less timing.

The rod was probably bent from a hydraulic event in the combustion chamber at one time (head gasket leaking into cylinder). The noise you heard was probably the bent rod contacting the skirt of the piston . It happened to me on an LT1 but i didnt drive it at all after it happened.