Low oil pressure
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From: Detroit
Well to better explain it (not to defend it..), the scotch brite 'treatment' was done with the bearings out of the engine. They were then cleaned and installed, so there is no reason to assume that pieces of the pad made it into the engine. My thought was that taking off that .0005" overlay would result in an oil clearance up to .001" oversized, which is compounded with the fact that the crank was already on the low side of oil clearance tolerance. That in turn could theoretically cause the clearance to be too great and the rest would be history.
This makes sense to me...some agree wholeheartedly, and others are skeptical. I don't want to try rebuilding this thing without knowing exactly what happened. I'll be damned if I make the same mistake twice...
This makes sense to me...some agree wholeheartedly, and others are skeptical. I don't want to try rebuilding this thing without knowing exactly what happened. I'll be damned if I make the same mistake twice...
Staging Lane
Joined: Dec 2006
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From: Calgary, Alberta
The whole point with Scotchbrite is you can't get everything cleaned 100%.
Plus your bearings are all gouged to start with. If bearing manufacturers wanted you to gouge them they would be gouged when you get them.
My comment about damaging injection molds is that while you think you are polishing the surface, you are really gouging it and little pieces stay there to circulate in the engine. If you have a rusty part and polish it with a Scotchbrite pad, that is what it is for.
Just NEVER use a Scotchbrite pad around an engine and you will be good.
I do have Scotchbrite pads here at the shop and use them for rough cleaning etc and they work fine for that.
I've attached a photo. I took a hunk of alum I had around, and filed, then sanded and finally polished it with Mothers alum mag wheel polish. (What mold polishers use!) You can see my camera reflected on the left and Scotch brite scratches on right. I took about 10 minutes to do this so it isn't perfect by any means but you get the idea!
Plus your bearings are all gouged to start with. If bearing manufacturers wanted you to gouge them they would be gouged when you get them.
My comment about damaging injection molds is that while you think you are polishing the surface, you are really gouging it and little pieces stay there to circulate in the engine. If you have a rusty part and polish it with a Scotchbrite pad, that is what it is for.
Just NEVER use a Scotchbrite pad around an engine and you will be good.
I do have Scotchbrite pads here at the shop and use them for rough cleaning etc and they work fine for that.
I've attached a photo. I took a hunk of alum I had around, and filed, then sanded and finally polished it with Mothers alum mag wheel polish. (What mold polishers use!) You can see my camera reflected on the left and Scotch brite scratches on right. I took about 10 minutes to do this so it isn't perfect by any means but you get the idea!
Last edited by Albertan; Feb 20, 2012 at 05:11 PM.
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From: Detroit
The whole point with Scotchbrite is you can't get everything cleaned 100%.
Plus your bearings are all gouged to start with. If bearing manufacturers wanted you to gouge them they would be gouged when you get them.
My comment about damaging injection molds is that while you think you are polishing the surface, you are really gouging it and little pieces stay there to circulate in the engine. If you have a rusty part and polish it with a Scotchbrite pad, that is what it is for.
Just NEVER use a Scotchbrite pad around an engine and you will be good.
I do have Scotchbrite pads here at the shop and use them for rough cleaning etc and they work fine for that.
I've attached a photo. I took a hunk of alum I had around, and filed, then sanded and finally polished it with Mothers alum mag wheel polish. (What mold polishers use!) You can see my camera reflected on the left and Scotch brite scratches on right. I took about 10 minutes to do this so it isn't perfect by any means but you get the idea!
Plus your bearings are all gouged to start with. If bearing manufacturers wanted you to gouge them they would be gouged when you get them.
My comment about damaging injection molds is that while you think you are polishing the surface, you are really gouging it and little pieces stay there to circulate in the engine. If you have a rusty part and polish it with a Scotchbrite pad, that is what it is for.
Just NEVER use a Scotchbrite pad around an engine and you will be good.
I do have Scotchbrite pads here at the shop and use them for rough cleaning etc and they work fine for that.
I've attached a photo. I took a hunk of alum I had around, and filed, then sanded and finally polished it with Mothers alum mag wheel polish. (What mold polishers use!) You can see my camera reflected on the left and Scotch brite scratches on right. I took about 10 minutes to do this so it isn't perfect by any means but you get the idea!
The mains had too much clearence, should have gone .010 under and gotten the right bearings. Also use lots of assembly lube, and spin the motor over 50x on the stand. That will clearance both the rod and mains with no heat or load on them. You will smell it when it builds a little heat (smells like old motor) This dosent use scotch brite 
What do your cam bearings look like? Also what was the clearence?
I'd say he owes you a regrind, balance and a full set of bearings. (cam, main and rod)
What do your cam bearings look like? Also what was the clearence? I'd say he owes you a regrind, balance and a full set of bearings. (cam, main and rod)
Last edited by 1dirtybird; Feb 20, 2012 at 08:20 PM.
Bearings look like crank was wobbling in the main caps. I had a Ford Motor do this when the machine shop got the cranks mixed up. Little to NO oil pressure after break in period. Too Much clearance. (I didn't install crank) Did you plasti-gauge before installing?
Staging Lane
Joined: May 2010
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From: Tucson, Az
Scotch-brite is not the issue. Its use is debatable, but to take all 5 mains down to the steel liner, would require a whole scotch-brite pad to be left in each main. To tell me that the small amount of abrasive that could possibly be left over even after liberal use of lacquer thinner and a rag, would be enough to waste all 5 mains, yet not damage the rods before being washed out by the oil is simply asinine. Plastiguage is for stock rebuilds, micrometers and a dial-bore gauge were used on this build. Oil clearance was on the loose side, but still within specs, and it wasn't built by the machinist who ground the crank.
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From: Detroit
The mains had too much clearence, should have gone .010 under and gotten the right bearings. Also use lots of assembly lube, and spin the motor over 50x on the stand. That will clearance both the rod and mains with no heat or load on them. You will smell it when it builds a little heat (smells like old motor) This dosent use scotch brite What do your cam bearings look like? Also what was the clearence?
I'd say he owes you a regrind, balance and a full set of bearings. (cam, main and rod)
What do your cam bearings look like? Also what was the clearence? I'd say he owes you a regrind, balance and a full set of bearings. (cam, main and rod)
That's only if I can get some hard evidence on what happened to this one and prevent it from happening again. When the clearance in the mains is to loose the crank will beat the cups out of the bearing. Notice the outer edge's are still there. Crank doesn't need to be bent. It wouldn't turn in the mains if it was..
Plasti-gauge is common sense and I use it on $6000.00 short blocks. Too say that plasti-gauge is for stock rebuilds is THE STUPIDEST thing I have heard in awhile. And I am a volunteer big brother at the local retard ranch..
You can use all the micrometers and bore gauges you want too, but If you don't know how to read them correctly. It doesn't matter. Bottom line is that the main bearing tolerances are too loose, at least that is what the visual evidence that you have provided has shown.
(Side note) If the main caps were ALL loose, than the bearings would have spun.
Plasti-gauge is common sense and I use it on $6000.00 short blocks. Too say that plasti-gauge is for stock rebuilds is THE STUPIDEST thing I have heard in awhile. And I am a volunteer big brother at the local retard ranch..
You can use all the micrometers and bore gauges you want too, but If you don't know how to read them correctly. It doesn't matter. Bottom line is that the main bearing tolerances are too loose, at least that is what the visual evidence that you have provided has shown.
(Side note) If the main caps were ALL loose, than the bearings would have spun.
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Verdad Gallardo Staging Lane
Joined: May 2010
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From: Tucson, Az
I was simply stating that I am not comfortable using plastiguage in performance applications. I am much more accurate with a micrometer and a dial-bore than I am eye-balling the width of a smashed piece of plastic next to a piece of paper. No need for name calling.
Something I believe worth noting here is like previous poster stated You can't get all the Scotcbrite out because bearings are designed to allow small pieces of grit and so forth "embed" into the bearing surface to prevent the grit and so forth from trashing the crank in a hurry . Also worth noting is for example when You sand something such as a crank or say a pulley for a squirrel cage blower when You start sanding You actually make that surface larger as opposed to the surface becoming smaller right away ,,,,,,,the courser the grit the larger it becomes to start until You've sanded for a while and progressively work down to finer sand paper , then at some point it's the same size to start and eventually it becomes smaller than when You started . Scotch-brite is'nt any different . The reason is every little scratch goes into the surface deeper than flush with the surface while on either side of every scratch is pushed to the side and consiquently raised above the surface . Want to test this out ,,,,have a swamp cooler blower shaft with the pulley on ,,,,,,,remove the shaft and take some 80 grit and sand that shaft for about 15 or 20 seconds aggressively and put that pulley back on and tell me how easy it was"nt" to put back on .
I agree that too large of bearing/crank clearance on the mains is most likely what caused those main bearings to go south quick ,,,,,,,,but I also would'nt recomend anyone using Scotch-brite pads on "new" or used bearing surfaces prior to assembling an engine ,,,,,,,,,,,,look in a mirror and say "Scotch-brite" padding "new" engine bearings prior to assembling engine " and tell us if that sounds crazy or not ?
The only thing I would maybe consider suggesting would be to use 2000 or 2500 grit sand paper and wet sand lightly the bearing surfaces but honestly I would'nt even suggest that but I would suggest using Meguiers swirl remover and 1 of those yellow cloth shammies on bearings ,,,,,,that swirl remover is the finest polish I'm aware of ,,,,,,maybe others know of something better .
The only thing I would maybe consider suggesting would be to use 2000 or 2500 grit sand paper and wet sand lightly the bearing surfaces but honestly I would'nt even suggest that but I would suggest using Meguiers swirl remover and 1 of those yellow cloth shammies on bearings ,,,,,,that swirl remover is the finest polish I'm aware of ,,,,,,maybe others know of something better .
Staging Lane
Joined: Dec 2006
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From: Calgary, Alberta
Bigredcummings
When I made my Scotchbrite comment, I had only seen the mains. He hadn't opened the rods yet. So in this case it probably wasn't directly Scotchbrite and was excessive clearance.
Chrisfrost, in the injection molding game, mold polishers polishing an aluminum
mold to a mirror finish actually use Mothers mag wheel polish for the final finish.
I don't know if that is the finest polish around, I know I have diamond paste for mold polishing for steel molds, but Mothers works for them. I'm just glad I'm not having to polish molds for a living!
The hunk of aluminum I polished, I used a file to smooth it out, 400 grit wet/dry, 600 grit at 90 degrees,1000 grit at 90 degrees, 1200 grit and finally 2000 grit. The Mothers. Took 10 minutes. Took 30 seconds to ruin it with the Scotchbrite pad.
Personally, I would never touch a bearing surface with anything except maybe 2000 grit if there was a good reason. I do use plastigage. No math errors with it vs using micrometers.
When I made my Scotchbrite comment, I had only seen the mains. He hadn't opened the rods yet. So in this case it probably wasn't directly Scotchbrite and was excessive clearance.
Chrisfrost, in the injection molding game, mold polishers polishing an aluminum
mold to a mirror finish actually use Mothers mag wheel polish for the final finish.
I don't know if that is the finest polish around, I know I have diamond paste for mold polishing for steel molds, but Mothers works for them. I'm just glad I'm not having to polish molds for a living!
The hunk of aluminum I polished, I used a file to smooth it out, 400 grit wet/dry, 600 grit at 90 degrees,1000 grit at 90 degrees, 1200 grit and finally 2000 grit. The Mothers. Took 10 minutes. Took 30 seconds to ruin it with the Scotchbrite pad.
Personally, I would never touch a bearing surface with anything except maybe 2000 grit if there was a good reason. I do use plastigage. No math errors with it vs using micrometers.
Staging Lane
Joined: May 2010
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From: Tucson, Az
Here's where I get to admit that I had a dumbass attack. In measuring the oil clearance, with the mic and the dial bore, I got .0045, and divided by two. 
giving us .00225 which is in spec. Not realizing in the moment that I was supposed to have total clearance of that. So basically the mains had double the bearing clearance they were supposed to. I just didn't catch myself because the crank was supposed to have been on the low side of factory, which made perfect sense the way I did it in my head. Oh well, won't make that mistake twice.
giving us .00225 which is in spec. Not realizing in the moment that I was supposed to have total clearance of that. So basically the mains had double the bearing clearance they were supposed to. I just didn't catch myself because the crank was supposed to have been on the low side of factory, which made perfect sense the way I did it in my head. Oh well, won't make that mistake twice. Last edited by BigRed Cummins; Feb 21, 2012 at 10:40 AM.
Just curious, how would it wobble in the main caps? Do you mean bent crank?
I bought the right bearings for the job, as I had no intentions of turning a perfectly good crank. It was just getting polished for the new build. Cam bearings look good, clearance is spot on there as well. I won't be messing with that crank, I don't want to chance it on something that I want to be reliable. If anything, it will likely get the crank that me and my buddy came and grabbed from you in December That's only if I can get some hard evidence on what happened to this one and prevent it from happening again.
I bought the right bearings for the job, as I had no intentions of turning a perfectly good crank. It was just getting polished for the new build. Cam bearings look good, clearance is spot on there as well. I won't be messing with that crank, I don't want to chance it on something that I want to be reliable. If anything, it will likely get the crank that me and my buddy came and grabbed from you in December
That's only if I can get some hard evidence on what happened to this one and prevent it from happening again.I would have that crank turned .010 and grab .010 bearings. Your machine shop shouldnt have recomended polishing it that far. JMHO.. Stock LS cranks can handel alot even .010 under. Always check with plasti-guage. Its also stretches the new arp rod & main bolts a couple times.
Bad part is you need to dissamble and clean everything, there will be bearing metreal in all the oil passages and gallys. Meaning new gaskets and such.
And I wasnt saying you got the wrong bearings lol i ment .010 under and .010 bearings so sorry bout that.
I can say I would totally be capable of making that mistake... 
to make sure I'm not...I put my crank in last weekend and the plastigauge came out to ~2-3 thousanths, closer to 2. Does that mean total clearance or do I need to double that?!?
to make sure I'm not...I put my crank in last weekend and the plastigauge came out to ~2-3 thousanths, closer to 2. Does that mean total clearance or do I need to double that?!?
that is total... Your crank is sitting firmely on the top bearings when checked.
Edit... there is zero clearence on one side of the crank when useing this method...
Just wanted to be clear
Edit... there is zero clearence on one side of the crank when useing this method...
Just wanted to be clear
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From: Detroit
I've been told not to turn the crank and reuse it in my engine. Supposed to make it weaker (debate if you like, I don't claim that statement lol), so I will just use the new crank. I want the engine to be as strong as possible, and it won't cost a whole lot for a new crank.
That is perfect and that is your total.
I've been told not to turn the crank and reuse it in my engine. Supposed to make it weaker (debate if you like, I don't claim that statement lol), so I will just use the new crank. I want the engine to be as strong as possible, and it won't cost a whole lot for a new crank.
Good luck and Now you have a racing WAR STORY..
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After further inspection, the bearing caps were annealed when they got hot and are now somewhat loose in the register. I can get set of caps from another 2008 Gen 4 engine, and research is saying that it will just need to be bored and honed. Has anybody done this before and if so, how close were the parting faces with the new caps?
