This is the first time I'm doing a head gasket job on my D16Z6, so apologies in advance for any newb questions. I took off my head and took it to a local machine shop to check for flatness and resurface. Without taking a straightedge to it first, the machinist said that it's definitely warped because the head always warps as soon as you take off the head bolts. (Is this true?)

When I got it back, there were visible milling marks and a few scratches on it. I can feel the parallel ripple lines from the machining using my fingernail. It doesn't quite feel as bad as like an LP record; its feels maybe closer to 200 grit sandpaper, though I can certainly at least count the ripples by using fingernail alone. (It was WAY smoother before I gave it to him, fingernail wouldn't even feel anything.)

I don't have a profilometer to determine the roughness average. The machinist wouldn't tell me what the RA was, just said it will work with my MLS head gasket.

From my research, it seems like MLS head gaskets (I'm about to install a Fel-Pro MLS, which allows for up to 80RA) need to be very smooth in order to seal right - in theory, I shouldn't be able to feel the lines by fingernail.

First pic (the still dirty head) is from before taking to the shop.


BEFORE taking to machine shop

The rest is after taking to machine shop for resurfacing.

AFTER machine shop resurface

Close up of AFTER machining. Note the milling marks.

Does this look okay? Am I freaking out over nothing? I'm not shooting for a performance build, I just want to keep it stock. Maybe the camera flash is exaggerating some of the scratches, but there are indeed some random pockmarks and scratches here and there.

I've never been to this machinist before but it appears he does do work for a bunch of local repair shops.

 

I've seen worse. Just make sure you're using a good headgasket, preferably a factory Honda one

 

It looks like they didn't have a clean surface and just dragged it along the table...

 

Seeing lines means nothing. Drag your fingernail across it, can you feel the lines?

Moved to the machine/assembly sub forum.

 

he said he could feel the lines 👆

 

Yes, I can feel the lines just barely, though its bumpy enough that I can count the ridges by fingernail feel alone. Is that bad enough to cause problems?

 

I would go by the specs on the oem headgasket your using and following the ra roughness/ smoothness, if the head doesn’t meet the specs of the headgasket then it’s best to take to another machine to do the required specs or take it to the original machine and let him know that it’s not in within specs of the headgasket your using and make him do it again. Get it done right the first time.

 

That is 100% false. Been a technician at a Honda dealership for over 7 years, and as long as you take off the head bolts in sequence and the proper amount of turns per bolt each time around the head, you will not warp the head. Doing warranty piston ring replacement on V6 many MANY times and we NEVER warped heads by simply pulling them off.

This machinist is either an idiot, or he is lying to you to get money from you. Find a new machinist.

 

Yea, I suspect the guy was hustling me. When I brought the head in, I mistakenly thought the coolant plug under the timing cover (behind the cam pulley) was a heat tab, so I mentioned I thought it might have been resurfaced once before. He then said that it might be impossible to resurface, since he eyeballed it and said there might be too much taken off already, and that my motor was running on super high compression. (I should have bailed on that BS right there and then)

Later I realized it wasn't a heat tab, and thinking back, there was no evidence to suggest it was ever resurfaced, nor was the HG ever done before (I have records going back to the 90s). There was still around 1mm of "meat" above the little circle markers on the head. He later even sold me on a valve job, which I now suspect was unnecessary (I did a compression test prior to head removal, it was fine).

Lesson learned, next time better to take a straightedge to it before trusting a machine shop. This was a $250 mistake (most of it from the valve job).

Anybody live in the SF bay area and have good leads on a decent machinist?