Block or head resurfacing?

[flyinwrenches]

Ok, I have a technical question about head and block resurfacing. So, I am currently contemplating on buying a lml truck that says it has blown head gaskets. Now, that isn't too big of a deal for me really. But, upon doing some random reading, someone said the engine block needs refaced??? I usually just have them check the heads and have them resurfaced and throw on some thicker gaskets if need be, but should the block be resurfaced too? I haven't did a duramax set of heads before. Just other rigs. I was going to pull the engine and at least put some new bearings and may rering it, depending on what all everything looks like. I have seen bad mating surfaces on big rigs where they are needing refaced due to pitting. I can't see a lml having much pitting though. Does their cast warp or something in the blocks? Anyways, do I need to send in the block to be refaced?

 

[Ron Nielson]

You will have to carefully check the block to make sure it is flat and in good condition. If the engine was crudded up, had rust, corrosion etc on the head surface of the block, you may need to have it surfaced. It's just something you will have to gauge when you tear it down.

 

[2004LB7]

Like Ron said. Most don't have to deck the block. Just check and clean it up. Heads on the other hand almost always needs to be done

 

[TheBac]

Moved to Engine Building. Changed title to more reflect the actual question.

As the guys said, its usually the heads that need resurfacing. The block may only need to be cleaned up lightly.

 

[kidturbo]

Since the factory LML gaskets were known to have a high rate of failure, unless someone really overheated it, likely just check the heads and install good gaskets an call it done. But ya never know for sure until ya tear it down.

 

[wagspe208]

I'm an engine builder. I come from Late model dirt, sprint car, drag, blown gas, blown alcohol. I am not a diesel guy, but I'm about to do my lb7.
My ONLY input is surface finish. You will see all sorts of guys very concerned about the Ra (surface finish average) of heads, and none seem to care about the horrible factory finish on the block.
With that being said, the factory blocks sure seal a long time.
So, I guess my point is, if it is flat, run it. If it is crappy, cut it.
I will be doing mine, but I have the equipment in the shop.

I'll even see if I can get a block finish from the factory to compare.