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Not a happy day here, well proven forged LS6 with a new rebuild (pistons & rings, H bearings mains and rods, GM cam bearings, oil pump, nothing else). Motor worked awesome from minute one! Cold oil pressure 60psi idle and 80psi at 2k rpm. Hot oil pressure 50 idle, 60 at 2000rpm. All looking good........except it was making copper from the start. At 100kms, the filter was full, and the oil "glimmered". I drove it another 600kms (mostly highway), just to see if it would stop. Uhuh, this stuff never gets better. Pulled the pan today and the thrust bearing is toast...on the flywheel side. However, the crank thrust surface looks good, it's not tore up. It's a 5M with a slightly stiffer clutch, but nothing crazy. I have no idea why this happened, but I'm thinking of slipping in another set of #3 bearing sets and see what happens. The motor is in a swap car, and it's removal in not easy. Comments, advice????
Had the same thing happen on mine. Clevite H bearing.
Crank thrust surface looked fine.
My machinist couldn’t remember what the clearance was at assembly. I’m sure it was in spec though, he is very ****.
Mine is an auto trans, but it never had an issue with the stock bearings.
I switched to a forged crank and King bearings. Builders over on YB said King and ACL have a better bearing, particularly the thrust. I believe ACL sells just the thrust set.
I also did a small mod to the bearing to feed some pressurized oil to that surface. You can google it. Takes 30 seconds with a small file.
Did you assemble the engine and if you did, did you follow the recommended procedure for that bearing ? I forgot to knock the crank back and forth and didn't realize until I had a couple of pistons installed. I did not want to take everything back apart and decided to run it, I ended up with what you have. I did monitor the oil and with no improvement in 1000 miles or so I had to yank it out. Tore it down, cleaned everything, reassembled with new main and rod bearings. 15,000 miles later things are good, oil never looked that bad again and oil filters are clean. Look into that process for seating the thrust bearing and ask yourself if you think you can do that in the platform you have. I threw the time saving dice the first time and lost.
Not a happy day here, well proven forged LS6 with a new rebuild (pistons & rings, H bearings mains and rods, GM cam bearings, oil pump, nothing else). Motor worked awesome from minute one! Cold oil pressure 60psi idle and 80psi at 2k rpm. Hot oil pressure 50 idle, 60 at 2000rpm. All looking good........except it was making copper from the start. At 100kms, the filter was full, and the oil "glimmered". I drove it another 600kms (mostly highway), just to see if it would stop. Uhuh, this stuff never gets better. Pulled the pan today and the thrust bearing is toast...on the flywheel side. However, the crank thrust surface looks good, it's not tore up. It's a 5M with a slightly stiffer clutch, but nothing crazy. I have no idea why this happened, but I'm thinking of slipping in another set of #3 bearing sets and see what happens. The motor is in a swap car, and it's removal in not easy. Comments, advice????
Thanks
G.M.
What was thrust clearance set at? I’ve never......repeat, never put an LS together that didn’t need thrust clearance opened up, except with GM crank and GM bearings. Any aftermarket bearing set is designed with you custom setting your thrust numbers. You cannot just throw a set of Kings or Clevites in and go. The thrust must be addressed. Could live a few minutes, could live a few years, but it needs addressed. I always give an LS at least .0035 thrust minimum. Ive set them as big as .0100 for auto trans setups with aggressive converters.
Did you assemble the engine and if you did, did you follow the recommended procedure for that bearing ?
Yes sir. And, yes sir, the procedure was followed to the letter.
What was thrust clearance set at?
0.005-0.006 out of the box. So I left it as it was what I consider reasonable.
I put another in last night since the crank seemed fine. Lots of assembly lube, surgically clean. I pulled another main cap of, and a rod, the bearings looked perfect. The oil filter did it's job, so there is hope. We'll see how it goes when I fire it up later today.
In my experience, something like this is more common with automatic transmissions, but I’ve seen the same thing happen in an engine I built with a manual trans. It had .007” clearance, but there was something with the drivetrain setup that caused the input shaft to load the crank forward when the bellhousing bolts were torqued.
GM, what bearings are those in the first pic? Most aftermarket bearings have oiling grooves cut in the thrust face. For instance Clevite has 2 grooves on one side and 3 grooves on the other side. 3 grooves side always goes toward rear (flywheel) side of engine. I just fit another set of mains this morning for a big power build, and went with .0055.
GM, what bearings are those in the first pic? Most aftermarket bearings have oiling grooves cut in the thrust face. For instance Clevite has 2 grooves on one side and 3 grooves on the other side. 3 grooves side always goes toward rear (flywheel) side of engine. I just fit another set of mains this morning for a big power build, and went with .0055.
All of the clevite bearings I have seen, do not have grooves in them, unless someone modded them.
GM, what bearings are those in the first pic? Most aftermarket bearings have oiling grooves cut in the thrust face. For instance Clevite has 2 grooves on one side and 3 grooves on the other side. 3 grooves side always goes toward rear (flywheel) side of engine. I just fit another set of mains this morning for a big power build, and went with .0055.
Correct, there "were" 3 groves there.....LOL. They are Clevite "H", unmodified, installed with the 3 groves towards the flywheel.
I’ve seen the same thing happen in an engine I built with a manual trans. It had .007” clearance, but there was something with the drivetrain setup that caused the input shaft to load the crank forward when the bellhousing bolts were torqued.
KCS, that's a great comment, I've checked the clutch, which seems fine. It's in a transaxle car with a torque tube, P944.. I'll make sure everything looks like it was, and worked without issue for 5 years and many hard miles. I changed the TB in the car last night, with the TB out, the crank was free to move forward and aft until the crank hit the block, in both directions. It was just a sanity check to see if anything was pushing forward.
Followup - Buttoned her up last night, and so far all is well. I drove 45 minutes, no issues, oil pressure was as good, or maybe better than before. We'll see how the oil and filter look after a few hundred kms.
There seems to be some confusion here on the grooves of my bearings. The photo shows no grooves. However, there were groove when installed, 3 facing the rear. The thrust surface is worn down below the groove. They are 2199H.
I'll let you all know how it goes in a few days. Fingers crossed!
Here's my follow up to this post.....and not the one I hoped for. After replacing the thrust bearing, and driving an easy 350kms, the engine is still making metal, and only copper/brass. Exactly as before. I'm sure the new TB is being consumed. I'm beyond frustrated, I'm done. The car will sit until winter. Unless I say "F" it and just drive the snot out of it as is. This is the same look as the oil that came out before the thrust bearing replacement. Looks like a brain. This is what was in the oil that drained out of the filter. I didn't even cut it opened yet.....why bother?? remains in the drain pan This is the LS6 in a 84 944. We do this because the Porsche motor is unreliable ... how ironic. OK, and for more power, fair point!
.005-.006 is fine with a manual trans...what slave setup are you running for the clutch? Something is causing a clearance issue here. Look for input shaft wear at the tip or front of splines.
Wilwood 13/16 bore. It's been in the car for ages. This motor / swap is not new, it's been in the car since 2013. The motor was removed and freshened up over the winter. The old thrust bearing was mint. ... had I known!!
06-19-2020, 02:47 PM
Thrust bearing gone in 1000kms 
