What would cause scuffing on the piston skirts?
Thread Starter
Joined: May 2012
Posts: 1,796
Likes: 59
From: Elm Creek, NE
What would cause scuffing on the piston skirts? Just tore down the ls2 short block I blew up a few months ago. When I picked it up, I did a basic rebuild.
New calico coated rod bearings/clevite mains
New stock replacement rings
New deglaze/hone job
Crank polished
Engine was a h/c ls2 that put down 454/425 with more left in it.
Motor has roughly 2,000 miles on the rebuild. The rods/pistons were installed. Back in the same hole they came from.
Upon tear down, all the mains/rods had significant scratches around the bearing, crank looked fine.
The piston side skirts had significant gauling/scuffing on them, and it was not there before.
What could have caused bothe these issues? Motor saw 7,000 regularly.
New calico coated rod bearings/clevite mains
New stock replacement rings
New deglaze/hone job
Crank polished
Engine was a h/c ls2 that put down 454/425 with more left in it.
Motor has roughly 2,000 miles on the rebuild. The rods/pistons were installed. Back in the same hole they came from.
Upon tear down, all the mains/rods had significant scratches around the bearing, crank looked fine.
The piston side skirts had significant gauling/scuffing on them, and it was not there before.
What could have caused bothe these issues? Motor saw 7,000 regularly.
Thread Starter
Joined: May 2012
Posts: 1,796
Likes: 59
From: Elm Creek, NE
I rebuilt it. I kept it covered/blown down and washed out.
But I did not blow out the oil galleys when I got it back from the machine shop. Possibly some **** in the oil galleys from the machining process?
But I did not blow out the oil galleys when I got it back from the machine shop. Possibly some **** in the oil galleys from the machining process?
well its one of those things that you might not ever know what happened now... debris or whatnot!
Hell Yeah! Have you ever hung out in a machine shop? not the cleanest place on earth. Even some of the so called "clean rooms" in some machine shops are questionable at best. Always clean all the oil passages yourself after you get the block back from the machine shop.
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"But I did not blow out the oil galleys when I got it back from the machine shop. Possibly some **** in the oil galleys from the machining process?"
I think you answered your own question...Honing dust "gotcha"...
I think you answered your own question...Honing dust "gotcha"...
Thread Starter
Joined: May 2012
Posts: 1,796
Likes: 59
From: Elm Creek, NE
Well, I puled the other pistons and this is the only 1 with ANY scuffing at all. The block was just deglazed, not bored. SO I don't think it was a machining issue. WTH would cause this on 1?
Excessive piston to bore clearance can cause that...even a light hone job will remove some material, granted not much, but if it was on the loose side before it surely didnt help.
Launching!
Joined: Jun 2005
Posts: 277
Likes: 0
From: SC
Just wondering on the initial condition of the block before rebuild. You don't hone a cylinder unless it's been rebored, has damage in it, or the new ring material specifically requires a hone and then the grit is typically very fine unless it's chrome rings. Do you know what grit was used for the hone? Cylinders don't glaze which is the deposit of material like you see in a glazed flywheel or glazed brake drum. You also don't clean a honed cylinder with carb cleaner or any other solvent.
Last edited by SSellers; Jul 14, 2013 at 09:24 AM.
What I'm thinking.. Thread Starter
Joined: May 2012
Posts: 1,796
Likes: 59
From: Elm Creek, NE
Yes, this engine dropped an exhaust valve on the ls3 heads. Kaboom, murder she wrote. So I'm waiting on the new block to be machined.
What would you recommend to clean the bores etc out with after machine work then?
What would you recommend to clean the bores etc out with after machine work then?
Thread Starter
Joined: May 2012
Posts: 1,796
Likes: 59
From: Elm Creek, NE
The block was a 80,000 mile stock short block when I got it. I put new rings in, all bearings etc with a fresh rehone for the rings. I take it that the rehone was a no no?
Even after a machine shop calls a block clean and ready for assembly you
can always use a Dexron soaked rag or towel and get quite alot of honing
grit/dirt out of the crosshatching. Then you can wipe them several more
times with a dry towel and I really prefer the Total Seal quickseat powder to
smear on the cleaned bores then install the pistons dry. The powder helps to
seat the rings during assembly...good stuff. Also take a look at all the piston
skirts on the valley side....you will probably see consistently more scratches
than on the exhaust/outside skirt as too much timing/crappy gas/ and det-
onation causes the piston to rock in the bore...perhaps the primary ring gap
was not large enough for the power level/heat you were making...butted to-
gether then cracked off a small piece of piston material...tried to compress
said piston piece into .040" of quench then the piston and rod parted ways.
At high rpm the piston **** hitting the valve can bend it and the pushrod and
knock the valve locks off making you think that thats what happened first....
chicken or the egg sorta thing....really feel for ya sir !!!!
can always use a Dexron soaked rag or towel and get quite alot of honing
grit/dirt out of the crosshatching. Then you can wipe them several more
times with a dry towel and I really prefer the Total Seal quickseat powder to
smear on the cleaned bores then install the pistons dry. The powder helps to
seat the rings during assembly...good stuff. Also take a look at all the piston
skirts on the valley side....you will probably see consistently more scratches
than on the exhaust/outside skirt as too much timing/crappy gas/ and det-
onation causes the piston to rock in the bore...perhaps the primary ring gap
was not large enough for the power level/heat you were making...butted to-
gether then cracked off a small piece of piston material...tried to compress
said piston piece into .040" of quench then the piston and rod parted ways.
At high rpm the piston **** hitting the valve can bend it and the pushrod and
knock the valve locks off making you think that thats what happened first....
chicken or the egg sorta thing....really feel for ya sir !!!!