Head resurfacing yay or nay?

[Delta.Speed]

So as the tittle implies I'm looking to get some thoughts, opinions, and above all experiences with head resurfacing.

I'm pulling the heads on my LB7 and I'm planning on taking them to a reputable machine shop I've worked with before to have a valve job done, and to have them inspected for cracks, warping, etc.

I spoke to a diesel shop in my area and they told me that Duramax heads cannot be resurfaced or they'll crack.

Now I'm new to diesels but from working on gas engines for a long time that doesn't make much sense to me.... I've ALWAYS had heads resurfaced when I've had them pulled due to head gasket failures or any other head issue, to me it guarantees that I'll have a perfect fresh new surface for the head gaskets to mate to and it'll correct any slight imperfections on the head surface due to normal flex of the head casting over years of heating and cooling.

If Duramax heads cannot be resurfaced, are they just supposed to be slapped back on with the old nasty mating surface, or does this imply they are single use heads that everytime they come off they need to be replaced?

The shop said they would absolutely NOT give a quote for a head gasket replacement that doesn't include a new pair of heads at $3k+ for the pair.

Does their claim hold water?

Sent from my SM-S908U1 using Tapatalk

 

[gmduramax]

You can shave a little off of them, if you go to much I believe you run into issues with the Y bridge figment.

 

[Delta.Speed]

You can shave a little off of them, if you go to much I believe you run into issues with the Y bridge figment.

Aren't grade C head gaskets meant to account for the thickness lost when resurfacing? I believe I was told they are like .05 thicker or something like that.

Sent from my SM-S908U1 using Tapatalk

 

[gmduramax]

You would have to measure piston protrusion to be able to select the correct gasket. You should take quench into account even though most people do not. I believe they even make a grade D.
If you’re taking 2 thousands off the heads I wouldn’t worry about it one bit. Now if you’re taking 10 thousands off I would throw them away.

 

[Delta.Speed]

You would have to measure piston protrusion to be able to select the correct gasket. You should take quench into account even though most people do not. I believe they even make a grade D.
If you’re taking 2 thousands off the heads I wouldn’t worry about it one bit. Now if you’re taking 10 thousands off I would throw them away.

Thank you for the info. Ill get with my machine shop and get their thoughts on it. I just wanted to hear what others had to say about it.

Sent from my SM-S908U1 using Tapatalk

 

[Dean E]

I agree with others. Don't grind them for bumping up compression but I would ALWAYS clean them up to make sure they are true. Duramaxes do have issues with blown head gaskets. They need to be true before bolting them back down. Dean

 

[Chevy1925]

Cutting the heads has nothing to do with the compression or head gasket choice. The combustion chamber is in the piston, not the head. Hence GMDuramax saying you look at piston protrusion to determine hg choice or stick with what came off the truck originally

I know of heads that have been cut .010 or more without issue (.015 and up your asking for trouble but it’s case by case). Now these ain’t trucks trying to push big power and are not LLY heads that have known bad castings so consider that.

IIRC, over .007 cut off needs the valves recessed. The kind of warp it has dictates whether you should machine or not imho.

 

[Delta.Speed]

All great info guys. Thanks so much. I'm gonna try and finish getting the heads off today to take them to the machine shop tomorrow.

Sent from my SM-S908U1 using Tapatalk