I have a 2000 burb with a 5.3. Last year the motor went south due to a oil pump failure I have purchased a used motor that I am in the process of refreshing and installing.
First off, I know this is an LM7 but i don't see an lm7 section on the forum but i believe this is gen 3 motor correct? Is the lm7 the same as an LSx? I was hoping someone could clarify for me.
So among other things I am replacing the rear main. I bought the felpro rear main kit. The seal that came with it had a shorter depth than the original. I wasn' sure whether to flush it with the outer face or the inner seat. I went with the inner seat and not sure if that's correct or if it even matters.
Also I was kind of a DA and didn't realize what the plastic center piece was for and installed it without it. I was a little hard and I had to manhandle it a bit. I don't know if I ruined it or not. Should I replace it?

 

Your truck originally came with a 5.3 LM7. This is a genIII engine so you're in the correct section. We do not have sections for every iteration of these engines, so we keep it to genIII, genIV and now genV.

What is the engine that you bought? If you can't ID it, tell us more about it like what vehicle did it come out of.

 

The motor i bought came out of an 02 suburban. It's a 5.3 as well. Block is identical but there are few minor differences on the intake. The motor appears to be in good shape.
I swapped lots of 350's back in the day but don't really have too much experience with the newer motors.

 

It should be pretty much identical-including the intake manifold. If not, swap on the parts from the original.

No doubt both engines suffered with poor performing PCV systems. I suggest you pull the intake and clean up the ports and soak the manifold in de-greaser. It's always a GREAT idea to do the LS6 PCV swap: http://www.ls1howto.com/index.php?article=18

New knock sensors because they're under the valley cover AND intake manifold. A new ACDELCO oil pressure sending unit, because it's a bitch to change later.

Next pull the oil pan and check for excessive gunking. Consider a new timing chain and oil pump. Front & rear crank seals are waay easy now.

 

I'll check out that link. I did notice that my old lm7 had a egr pipe connected to the exhaust the the new one does not have one. I was curious if i could use the new setup but wasn't sure about what would happen since there would be no egr valve and if that would cause it to throw codes.
I have pulled the pan and front timing cover. Doesn't look too bad. I replaced the oil pump but kept the timing chain because it looked good and was nice and tight.
Replaced the front and rear seals and got schooled in removing in re-installing the harmonic.
I pulled the intake tonight and cleaned up the mating surface.
Did you see my question about the oil seal? Not sure if i should leave it as is or replace it.

 

The original LS rear main seals were dual lip and needed a tool to set them right. New seals are single lip.

If your original engine had a EGR setup, you'll need to replicate it on the replacement engine. Your PCM will look for it.

 

So is the LM7 an LS1. If not what is the distinction?

 

All of these engines have the same architecture. LS1 was the original 5.7L, the LM7 is a 5.3 with an iron block and a different intake manifold with a higher throttle body to clear water pump mounted fans that trucks use.

GenIII LS engines have a 24x crank reluctor ring and a 1x cam reluctor. GenIV LS engines use a 56x & 4x system.

 

What about the Crank Position Sensor. Should I replace it as well?

 

Crank & cam sensors are passive components and generally don't go bad. If they work, no sense spending good money on new ones.

I suggest the knock sensors because over time their metal bodies rust & rot.

 

Thanks a bunch for all the info so far.

What about the transmission shaft seal. Should I replace it or leave it be?

 

If it's some sort of a wear item such as a seal and it's impossible to access with the engine or transmission installed, I'd replace it while everything was out.

 

Roger that. I usually drill it and use a slide hammer on these types of seals. Sound ok?

 

Can anyone tell me the size on the hex head torque converter bolts? Pretty sure there metric and my 5/16 was a hair small. My book doesn't list it and could find it with a google search.

Update: It's an 8mm. I stripped the first one. Used a little heat and a punch and got it out. The other two came out with some heat.