I went to pull the stock cam out today in preparation for finally assembly of my junkyard LQ4/LS2/LS3 hybrid and couldn't get it more than half way out. Hear a little clicking noise when I rotate the cam so I look down the lifter bore to find one of the cam bearings has pulled free from the block and is "stovepiping". Finally work the cam out by using a screwdriver to square up the canted bearing and sure enough a journal is scored so it's a spun cam bearing......... Damn.

Now everything makes sense: Non-wrecked Fedex van that I pulled the 6.0 from was retired because the oil pump pickup o-ring split (I found it and fixed earlier) so it lost oil pressure and spun the cam bearing. Low oil pressure light comes on and valve train gets loud so Fedex junks it. Guess it's better to have learned it now then after I have it in the car!

So I've got a Gen 3 LQ4 long block with a spun cam bearing and a Gen 4 L96 bare block that had a spun rod bearing. Which one would you use for the rebuild? I'm leaning toward the Gen 4.

Thoughts?
S.F.

 

Use the newer motor the other motors scrap once it spins cam bearing

 

I was afraid of that. It's scrap because once the bearing spins it grinds the block and opens up the bearing bore so the bearing won't fit securely anymore, correct?

S.F.

 

You can buy over size cam bearings, why not repair it?

 

Well after deciding to build the gen 4 block I had a friend express interest on the LQ4. Since neither of us knew if it was good I let him take it to his machine shop to be checked out before money changed hands. Come to find out the cam bore was perfect and new bearings went right in properly. I guess what I read about the bearing shells shrinking from lack of oil is true and when the shell shrinks it can't grind away the bore.

Glad to know that it can still be used (going to be a 408 soon) and that maybe more of these are actually salvageable.

S.F.

 

As the gen4 block spun a rod bearing, the main bearing bore will more than likely need re-boring. And the crank journal is probably wiped too. No doubt this block & crank are done for.

A machine shop should be able to pop in a new set of cam bearings into the gen3 block. At worst, the cam is wiped.

Keep in mind these engines use a different PCM setup, the gen3 24x, the gen4, 58x. You'll need to match it to the PCM setup in the vehicle. You can't get one to work with the other.

What vehicle is this going into?