Ok, I will start at the beginning. I had a salvage yard 6 liter that had around 30,000mi on it and all was fine. I detonated it and broke a piston so I had some custom diamonds made up, pulled the heads and pan, honed with a brush hone, washed, washed and washed the cylinders and the rest of the motor and put it back together without even pulling the block. It went about 3000 miles and lost all oil pressure-the relief valve in the pump hung up. Tore it down and found metal throughout the motor from a completely gone rear surface of the thrust bearing. I wrote it off as being caused from not cleaning the motor out good enough after the in truck hone job.

So I pulled the motor and rebuilt it from the ground up using all new parts except the pistons and rods. The thrust surface of the crank was ground down-looked like a bench grinder had been used on it! So I pulled the crank out of my 19,000mi 5.3, had it checked and cleaned and used it (had it balanced) This motor went 5000miles and set a code for crank sensor. I could grasp the balancer and move the crank back and forth what seemed like a quarter of an inch!! So I pulled it down and guess what? Thrust bearing wiped out again and crank ruined again.

I asked around and we determined that it had to be the trans or the torque converter pushing forward so I bought a new converter and built a completely different trans. I built a new motor this time using a different block, a new from GM crank, h-beam rods, new diamond pistons, etc. Whole new combo-different motor, fifferent trans. It went 500 miles and the trans broke so I converted it to a 4l80e Now it has been about 500 more miles and guess what-low oil pressure so I pull the pan. Lots of bearing flakes in the pan and oil pickup screen. The thrust bearing is starting to get ate up, but the crank surface is still ok, caught it in time this time.

Please, what the hell is causing this?? Has anyone else had a thrust bearing prob on these motors? I have never read about it on here if so. Any ideas will be greatly appreciated!

As a side note I bought a new crank and put it in my 5.3 that I had robbed the crank out of, and put it, the trans, and the converter from the "problem truck" into my old 94 truck and I have driven it 11,000 HARD supercharged miles so far with no thrust bearing probs. Why is the 6 liter doing this?

 

There are different length 6l cranks. The earlier models have a longer crank. I would look into that as the problem. The longer crank would account for the rear of the thrust bering being chewed up since the added length would be causing the tranny to be pushing the crank forward.

 

Thanks for the suggestion. I never thought about that, but it isn't the prob. I am aware of the crank length diff-it is on the 99 and 00 models and I am working with 01 and up motors.

 

TTT Anybody else? Surely someone else has at least seen this prob.

 

I am assuming you are using Federal Mogul main bearings right? I have never seen a thrust bearing that fit tight right out of the box. You will need to squeeze the sides in just a little to make it fit tight on the cap. Also, what was your crank end-play measurement?

 

My 6.0 had a severely worn thrust bearing as well. It was originally an ARE shortblock. It did last probably 12k very hard miles...but it was worn into the steel backing when I pulled it.

It had what I would say was excessive end play when I got it from ARE. And Ive heard from some that excessive endplay is common in LS1 build ups. Is it an aftermarket bearing problem? How can correct endplay be assured? I have always heard .003-.007 is the norm. I have heard from some in the LSx crowd that even up to .025 is acceptable. I want mine tight

BTW...mine is an M6 so its not just a manual problem. Maybe its 6.0 related?

Who has experience with this??

BTW...when i pulled mine it had about .060 endplay. Still ran good though.

 

Never heard of the problem before. We have built 2 iron blocks. Mine was set up with .006 endplay on the crank, and that was after removing some material off the thrust bearing. Car runs great and oil pressure is excellent. We tore down my friends for a new engine swap and his crank and bearings looked perfect. His had 20,000 miles on it of very hard driving and tons of track time. We both use valvoline 20/50 regular dino oil.