Combustion Chambers Dents?

[kawboy]

What are these marks in the combustion chamber? They look more pronounced from carbon, wiping them off, and the flash.

I've noticed this on a few 2g heads I've seen, all of which came off running motors.

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http://img26.imageshack.us/img26/2867/headtkj.jpg

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Link for larger pic:
http://img18.imageshack.us/img18/8586/head2x.jpg

Take note both of these marks are on cylinder 4, different heads, and a different pattern.

 

[viperlp01]

I cant see the pics because im at work but that is detonation or "knock".... Small little explosions that can hurt the walls and components.

 

[kawboy]

So how is this fixed? New head?

 

[viperlp01]

Ya but if they are not that severe then you should be good. You now know that you were knocking and that is not good. You need to take car of that...

It is also possible that it was a casting defect. When they made them it left little dimples..

 

[kawboy]

I'm just concerned the dents will cause more detonation or pre-ignition.

 

[crimsondragon]

Looks fine to me. It's not detonation. It's just normal wear and tear. If it was detonation, it would have a lot of actual dents.

 

[kahl23]

Looking at it, it looks like the pitting you see when you have coolant leaking across the surface of the block and/or head. Is it just in one cylinder or is it in all of them? Because if it's only in one or two, I'd say that it's probably the result of coolant seeping into the cylinder. Check the exhaust ports of the cylinder head for little white crystal deposits, which are a sign that coolant has been present.

 

[kawboy]

Would I be ok to re-use the first head with no worries?

There are no crystals present

Also both heads only have it in cylinder four and only where shown.

 

[kahl23]

I'd say yes, but first make sure the head isn't warped. Take a metal straight-edge and check for gaps lengthwise, widthwise and on both diagonals of the head.

 

[kawboy]

I checked that already and as far as I can tell, there's nothing noticeably warped about it.

Thanks