DanZ28

iTrader: (5)

A few months ago, I bumped the rev limiter (6900) at the track as the tranny just would not shift into 3rd gear, in which I ended up going through the traps in 2nd gear still getting me a 12.17@98 <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> . Well, after that I started getting a knocking noise, so I began going through the valve train in the process of elimination and found nothing wrong, so I figured I had spun a rod bearing. Anyway, take a look at the pics and see what ya think. I know there is something wrong and it must be the cause of the problem, but I always thought a spun bearing was just that, a bearing that has spun around in the rod. All the other bearings and crank was perfect, 22k on the motor..

<img src="http://mediaservice.photoisland.com/auction/Mar/2003326413980911315294.jpg" alt=" - " />
<img src="http://mediaservice.photoisland.com/auction/Mar/2003325628992982741428.jpg" alt=" - " />
<img src="http://mediaservice.photoisland.com/auction/Mar/2003323933973144526370.jpg" alt=" - " />
<img src="http://mediaservice.photoisland.com/auction/Mar/2003326200423344285330.jpg" alt=" - " />
<img src="http://mediaservice.photoisland.com/auction/Mar/2003329090868652660272.jpg" alt=" - " />

Sorry for all the pics!
Thanks for any opinions..

Dan

LOnSLO

iTrader: (15)

A spun bearing is one in which the oil film is gone, and the bearings are actually grinding metal to metal. This causes serious friction. So much that the bearing will spin around. I don't see any evidence of major scoring or bearing damage, so I doubt that is your problem.

DanZ28

iTrader: (5)

Thanks man, But I don't know what else it could be. The discoloration on the crank and bearings have got to mean something. I know this didn't spin, but the noise was a little different then normal, meaning it didn't knock all the time, just 1500 RPM and above if held constantly. I don't know of anything else to make that kind of knock accept may a crank main bearing. Anyway, more info would be great!

Thanks,
Dan

LOnSLO

iTrader: (15)

You say you couldn't shift into third at the track. Have you eliminated a possible broken clutch? Were all pushrods OK? What type of setup are you running?

kp

iTrader: (34)

That discoloration on the bearings and journal looks like something was in the oil. Could have even been what they assembeled the engine with if it sat a while.. If the crank touched the bearing it would instantly wipe the metal off the bearing, if it stays in contact with the crank it will seize to the crank and 'spin' inside the rod. Look at the back of the bearing and you can see if it has moved but I doubt it - from what I see it looks fine. Get some plastigauge or bring the crank and rods/bearings to a machine shop and let them measure everything.

When the car was running you should have shut off the injectors or unplugged the coil/plug wires one by one to see if the noise disappeared. If it didnt it was most likely in the valve train. Could be a piston hitting a head, could be a wrist pin, could be a lifter/pushrod, could be a lot of things. One can only guess over the internet, since you have it apart may as well check everything but it doesnt look like those bearings were the problem..

DanZ28

iTrader: (5)

LOnSLO, It didn't shift to 3rd on only that one run, it was fine the rest of the evening. The A4 is beefed up already, and at the time, I had some CNC S1 heads, TR224 cam, and pretty much all bolt on's.

kp, the push rods were good, lifters were good, no piston to valve problems. I agree, I didn't think about pulling the plug wire's, should of done that. I change the oil about every 2k and use Red Line. The # 7 and 8 rods are the only ones with this discoloration and the surface of the bearings seems to have more wear than the rest.

I'm having an all forged bottom end built anyway, but thought I could narrow the issue I had down. Maybe it was a wristpin, I'm sure if I wanted to really get into it, I could find out, but I'm just not that motivated <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> right now.

Dan

Jay 95WS6

i dunno about the discoloration on the brgs but with the pattern on the crank it almost looks like you were running juice or maybe you had some detonation issues. it is pure speculation but we used to get a similar pattern on our old small blocks when we ran juice. any idea on your rod brg clearances?? use a plastigage to check
Jay

DanZ28

iTrader: (5)

Thanks Jay! Your right, I have used juice a few times, three runs at the track and two runs on the dyno total. I didn't get the bearing clearance as I just pulled everything apart recently. At least I may know what the crank pattern is now. The noise I was hearing seemed to be coming from the middle of the engine and using a screwdriver to the ear method of listening to the top half of the engine, everything was fine up top.

Dan

DanZ28

iTrader: (5)

Cylinder bores look really good, still has the cross hatch marks from the original honing. What happens to the wrist pin to make it knock?

Dan

Jay 95WS6

how about a broken ring land? did you ever do a leakdown test?

DanZ28

iTrader: (5)

Didn't do a leak down test. To be honest, I was looking for an excuse to buy a forged motor, but I am curious to find whats going on with this one. It would be the ***** to find it is the tranny or something <img border="0" title="" alt="[Mad]" src="gr_images/icons/mad.gif" /> ..naahhh!

Dan

Pro Stock John

iTrader: (34)

My main bearings were heavily scored and your bearings look decent.

But when it knocked it was in the middle of the motor and it kind of high pitched.

My oil pressure was messed up too.

David Plum

Wrist pin you would feel it rocking piston on rod there would be resistance nos can kill wrist pins with that load on them were the main bearings good or ck cam bearings oil hole partial shut starve rods poss. get knock.

wrencher

iTrader: (2)

PSJ is right sounds like a pin. If you can run it, you can disconnect spark wire off one at a time & see if noise changes. This will tell you which cylinder the problem lies.

Pro Stock John

iTrader: (34)

When I spun some bearings a few years ago they looked really messed up, your bearings don't look that bad but you had something knocking, perhaps a bad wristpin? How are the cylinder bores?

DanZ28

iTrader: (5)

Thanks guys! I'm gonna check the wrist pins out now that it's apart..

Dan

LQ4somona

Are you running a hyd cam? If so mabye a lifter went flat. When you cycled everything to check the valvetrain, it was a low speed, probably by hand, right? If so you might not have noticed the lifter problem. It causes a slight ticing noise, somewhat similar to a rod knock, but not as deep. Hope that helps <img border="0" alt="[chug]" title="" src="graemlins/gr_chug.gif" />

DanZ28

iTrader: (5)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by LQ4somona:
<strong> Are you running a hyd cam? If so mabye a lifter went flat. When you cycled everything to check the valvetrain, it was a low speed, probably by hand, right? If so you might not have noticed the lifter problem. It causes a slight ticing noise, somewhat similar to a rod knock, but not as deep. Hope that helps <img border="0" alt="[chug]" title="" src="graemlins/gr_chug.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I originally thought that it was a lifter bleeding down to. When I drained my oil though, I found metal shavings, not a lot, but they were shiny and about 1/8"x1/8" in size.

Dan