Cylinder head mating surface imperfection, need advice

The adventure continues. I have been cleaning up the cylinder mating surface and found this:
IMG_0826.thumb.JPG.68032d2128ad82cd2bde8702d5cf36a3.JPG
 
When I run my fingernail over it I'm pretty sure I can't feel it, maybe ever so slightly, but I am still concerned about it. Any advice would be appreciated.

Looks like a surface scratch in the picture.

Sent from my SM-G900T using ThumperTalk mobile app

Insignificant and not subject to combustion pressures. I always copper coat all head gaskets anyways and that will eliminate and potential coolant seepage.

Looks like a surface scratch in the picture.

Sent from my SM-G900T using ThumperTalk mobile app




Surface scratch, like no big deal? First time doing this here.
Insignificant and not subject to combustion pressures. I always copper coat all head gaskets anyways and that will eliminate and potential coolant seepage.


How many coats of the copper stuff on the gasket? What made you start using it?

One to two LIGHT coats per side the night before assemble. You want just a thin film. Less is better then more.

While most head gaskets do have a sealing compound on them, this is a extra layer of security. You apply it 12 to 24 hours prior to assembly so as the material, while dry to the light touch, still has 'give'. As you assemble the engine, place the parts EXACTLY where they go, do not slide them about, that scratches/wears even the OEM gasket coating and can be cause for failure.

One to two LIGHT coats per side the night before assemble. You want just a thin film. Less is better then more.
While most head gaskets do have a sealing compound on them, this is a extra layer of security. You apply it 12 to 24 hours prior to assembly so as the material, while dry to the light touch, still has 'give'. As you assemble the engine, place the parts EXACTLY where they go, do not slide them about, that scratches/wears even the OEM gasket coating and can be cause for failure.


When are these surface imperfections a cause for concern? What's the measure for replace / machine vs run it?

Normal method of checking is with a straight edge and a bright light, if light passes, then it needs to milled flat. If it is a nick, the typical test is 'does it catch on a finger nail or is it a point of where head gaskets have failed?

Your head looks fine

As said above, nothing to worry about. Its more of a mark than a scratch from what i can see

It'll seal fine

IMG_0823.JPGIMG_0825.JPG

How clean do the mating surfaces need to be? The gasket material came right off, its as clean as it will get without scotch brite, which I prefer not too use.

thats fine

Clean enough to eat off. All old head gasket removed and cleaned with brake cleaner.

Looks good to me.

So I still haven't put the head back on. I was looking at it again tonight and I determined that when I run my fingernail over it I can feel it, albeit just barely. Doesn't catch or anything, but it's definitely a scratch. No idea how it ever would've got there, not by any dowels or studs.... kinda wonder if it's from the factory. First time apart. So the ultimate question is, now that I have determined I can detect it with my fingernail just barely, am I still good to put it together? More picsIMG_0839.JPGIMG_0840.JPGIMG_0841.JPG

The gasket material will easily fill and seal the scratch. I wouldn't worry about it at all.

Sent from my SM-G900T using ThumperTalk mobile app

Honestly, you are stressing over nothing. It will seal fine with a new head gasket

The biggest concern would be if there is raised material. If so, lightly knock it down with a stone . If it's is just an depression than don't worry about it.

Sent from my XT1650 using ThumperTalk mobile app

The fun continues

Well I got the head back on, but the bike is not assembled to the point of starting it yet. Went pretty drama free, moly lubed the threads and mating surfaces of the bolts, torqued the bolts in the manual specified order in two stages, 13 and then 27. What was odd was I went around a couple of times after the first round of 27 and the kept tightening until they all settled out at 27. It was different, sometimes they would start almost tight, loosen some, then start tightening back up. But they all seemed to settle out at 27 in the end but I was getting worried when the started to feel loose while tightening. That's usually the sensation of stripping a bolt but they all settled out at 27 so idk.

 

 

 

Prob just gaskets compressing and everything seating

If they have held 27 then you are ok

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now