Actually, I am in the same boat. I called for weeks until I found a shop that has fixed several blocks with spun cam bearings. It is a problem with the bearing manufacturer, the dimensions were not to spec and this is the end result. I am actually taking my block (spun middle #3) to the machine shop tomorrow. We will have to measure the #3 cam bearing hole to see if in fact it did remove material or not.

He said that with new durabond bearings, if the block is within spec it will live just fine. He said that taking the bottom end out makes it easier but it can be done with the shortblock assembled with no problem.

Furthermore even though the bearing spun it is still to small (ID) to fit over the cam journal (OD).

 

New cam bearings installed, with bottom end still intact. All cam holes measured well within spec. All bearings took relatively the same amount of pressure to drive in the block. New cam installed and it turns as free as any other ls1 we tried.

 

I wasn't sure anyone would do it that way. Good info to know.

 

It was actually very easy, lined the oil holes up and drove bearings into journals slowly checking for proper crush and alignment.

 

ls1bird was talking about my 6.0 we also have a shop willing to install the cam bearings with motor together they are changing all four with parts and labor 80$

 

I think GM needs to check cam bearing clearance a little better, i posted up here a few weeks back asking about the same issue with no response. while changing out my cam i had the #3 bearing pop out on me. My buddy works next to a machine shop and i ordered a set of durabonds and the machinist just installed the one. he said the others still look good. Only difference with my engine is that the new bearing pressed in tighter than normal as said from the machinist. and sure enough the cam was not spinning nice. So i had to use an old cam and score the journal inorder to grind the bearing down. the machinist says its not uncommon to have tight bearings. the only problem is a cam bearing scrapper tool cannot be used unless the engine is torn down which i was trying to avoid. got the cam to spin nice and im calling it good. just got the engine back in the truck and hopefully be starting it within the next week here. curious to see how everyone elses spun bearing problems turn out!!

 

My machinist told me he has done a few of these (6.0s'). Basically, the concern is low oil pressure and the cause is a loose/spun cam bearing. He told me that in 2004 (later in the model year) and beyond the cam bearing od is slightly larger then the early 2004 and older bearings. He machines out the cam bearing tunnel to match the later 2004 and beyond specs and installs those bearings and it's fine.

He also thinks that GM screwed up on those earlier units and probably didn't have enough bearing crush engineered in.

Hope this helps.

 

is there a certain range of years that this is a problem or is it common to all LQ's?

 

wondering the same thing myself....same with ls1?

 

He told me that he has seen it on the early 2004 and some earlier model 6.0's. I think they were mostly LQ4's, but we think the same thing happened to my 2004 LQ9. My oil pressure went from the normal range at a hot idle down to 1/4 after a hard hit on the freeway one night.

He said it's easy to see because the part number that is called out for the engine changes around mid year on the 2004. I'm "assuming" that early 2004 and all older 6.0's are the old design but this is an Assumption. You know what happens when you assume things---- ! He said the later cam bearing has a larger OD so the cam tunnel has to be bored out a little to accommodate it on the earlier units. This is nice though, because usually the engine block would be scrap otherwise.......

On my engine, my pressure didn't drop all of the way though. It would drop to around 1/4 at a hot idle. If it was near it's oil change the pressure would be slightly lower. Fresh oil and it is a tad above the 1/4 mark.

I cut the oil filter apart after the next oil change and I had bearing material in it (a decent amount). I did it on the next couple of oil changes and i had a little material each time but not as bad as the initial oil change. I figured the engine was done, but I've actually been driving it like this for about a year or so. I've probably put 35,000-40,000 miles on it since then! I'm thinking when I go to rebuild this thing, I'll probably need the jaws of life to get the cam out---or maybe it will just just fall out---don't know

Thought this information might help someone so I posted it in case you guys run into something like that. Good luck.