2G Is this normal in the combustion chamber?

[Simonsaysr1]

I noticed some weird pits in the cylinder head combustion chamber? Wouldn't this create a hot spot? What would cause this?

 

[jakk220]

Looks like marks caused from detonation. What does the Piston look like in that cylinder?

 

[AWD-Tony]

I think it’s shitty casting and or shitty aluminum. Had the same in only 1 & 4. Used 320 grit on dremel but didn’t remove too much since it was my first time messing with the head

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[motomattx]

Lots of them look just like that, likely detonation damage from just the stock tune on the hot corners of the chambers.

 

[AWD-Tony]

Lots of them look just like that, likely detonation damage from just the stock tune on the hot corners of the chambers.

Mine was only 1&4. Wouldn’t all 4 chambers be the same if it was detonation?

 

[ThunderChild]

I agree with @tk106 I see it on alot of the heads I pull, I'm thinking casting flaws, and they always seem to be worse on the end cylinders.

 

[silvreclips]

Mine was only 1&4. Wouldn’t all 4 chambers be the same if it was detonation?

It's common to only see detonation marks on 1 or 2 cylinders.

 

[EVLGSX]

Ive always seen the same

 

[motomattx]

Mine was only 1&4. Wouldn’t all 4 chambers be the same if it was detonation?

Not really, those cylinders are likely the lean ones or the hot spots on the cooling system.

 

[jakk220]

Yeah I have had it where it was only on one cylinder before. Its actually not uncommon. Here is a pic of my old 1g that had detonation marks on cylinder 4 only. Had the same marks on the head too.

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[1990TSIAWDTALON]

Take emery cloth to it by hand and just smooth out the spots so they don't get hot. Don't touch the fire ring area.

 

[jakk220]

I think it’s sh**ty casting and or sh**ty aluminum. Had the same in only 1 & 4. Used 320 grit on dremel but didn’t remove too much since it was my first time messing with the head

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That definitely looks like it was from detonation....

 

[AWD-Tony]

If you guys say so. Just strange to me it's always the end chambers.

 

[Simonsaysr1]

Looks like marks caused from detonation. What does the Piston look like in that cylinder?

Looks completely fine. Nor did I ever have knock really occur. I never noticed any audible detonation either

 

[Simonsaysr1]

I'll sand it out carefully I think it's a casting imperfection as well. My pistons look fine and it only appears to be on the ends of the head . Definitely caught my attention

 

[ThunderChild]

If you look at where the marks are on the head, they're off to the sides/ends. Then look at @jakk220 's pic And the detonation is closer the the valve edges, close to the quench area where detonation would start to occur. I'm not saying it's impossible for detonation to occur up in the pocket, but I think it's highly unlikely for that area to see that amount of marking and the piston to not be destroyed, or have marks in a corresponding area.

Like I said, I've seen at least a dozen of these heads with the same marks in the same spots, and I wouldn't be surprised if it's just a casting defect from foam cores boiling away, or gas in the sand making flow marks.

 

[AWD-Tony]

Jakks piston definitely show signs of detonation.

You can remove the carbon in those pockets with a brass wire wheel on a dremel if you have one.

 

[Simonsaysr1]

Jakks piston definitely show signs of detonation.

You can remove the carbon in those pockets with a brass wire wheel on a dremel if you have one.

thanks for the tip. i was thinking about those little carbon pieces, I couldn't get to them with just emery cloth,
seriously considering getting another head, but realllly dont want to dish out more money. my friend has one with bent valves, came off a 98 gsx(got to help him pull it for a 6 bolt swap). but i might have gouged the sealing area of the oil port tear drop. its all the way to the edge of the ring but stops right at it.. i tried so hard and it slipped forward and just hit the tip of the carbide. im going to double check it tomorrow with a head gasket. I'm seriously wanting to smack my self for not doing the easiest thing to do like jafro said and put the old HG on it first(didnt bring it with me to work). I got impatient and we were slow at work so i decided to go in the back with the air dremel and I honestly should have done it on my own time , so i could have made sure i didnt make this mistake.

 

[AWD-Tony]

Yikes. Yeah patience is key when it comes to things like this, as you already know. I just used a dremel on medium speed for the oil passage. Maybe it’s salvageable if you’re getting it decked???

 

[Simonsaysr1]

Yikes. Yeah patience is key when it comes to things like this, as you already know. I just used a dremel on medium speed for the oil passage. Maybe it’s salvageable if you’re getting it decked???

i dont think so , the gouge is pretty deep and would taper to a bigger gap the lower it got resurfaced. , im hopping that when I put the gasket on it.. it is inside the sealing ring and I can continue. if not its more money and time i guess. I feel pretty confident when I try it tommorrow its going to just barely (i mean just barely) make it or be over cut. I sure hope its not toast.

 

[EVLGSX]

This is an 80k never torn down 7 bolt. I pulled the head last year to change the HG and found the same thing as the OP. This is before it was really pushed. Id have a hard time believing this was the result of detonation after looking at those outer pistons but who knows.

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Not 100% sure how it got this way but I didnt want to leave it like this.

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I decided to fix what I found and ended up doing the valve job while it was off. Very easy to smooth out, the usual 80/ 180/ 320 by hand then some high speed rotary stuff followed by polishing. Go easy and stay away from the valve seats.

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And heres is where I ended up with it.

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[ThunderChild]

This is an 80k never torn down 7 bolt. I pulled the head last year to change the HG and found the same thing as the OP. This is before it was really pushed. Id have a hard time believing this was the result of detonation after looking at those outer pistons but who knows.

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Not 100% sure how it got this way but I didnt want to leave it like this.

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I decided to fix what I found and ended up doing the valve job while it was off. Very easy to smooth out, the usual 80/ 180/ 320 by hand then some high speed rotary stuff followed by polishing. Go easy and stay away from the valve seats.

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And heres is where I ended up with it.

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Yep seen the same thing on lots of Hyundai heads with low miles and several dsm heads. Still voting casting flaws. But nice job on the clean up @EVLGSX ! I have a few heads with similar CC issues and im doing the same thing to them currently.

 

[jakk220]

Hmm. Now you guys are convincing me that it's something with the casting. I just chalked it up as a hot spot for detnation. But those last pictures look like casting flaws...

 

[Crashmikejones84]

I noticed some weird pits in the cylinder head combustion chamber? Wouldn't this create a hot spot? What would cause this?

Most likely from detonation as he stated previously. I would also check your valve seats and exhaust valves for pitting. Very common on these when running too much boost without the extra fuel or a knock sensor that's not functioning properly. Check the ring lands for excessive clearance and also make sure from the top ring land to the top of the piston you dont see any deforming. Ran into this on my 92 tsi, although much more extensive. Hope this helps

 

[Simonsaysr1]

Here's the tear drop. I'm pretty sure it's toast