It'll take better eyes than I have to confirm but I think I see a crack between #5 exhaust valve and the prechamber. If so, that's where coolant leaked into the combustion chamber... and the head is toast.

I could be wrong because a cylinder burning coolant would have ash and other discolorations.

Sixto
87 300D

Hopefully not

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83 300D 328k mi (623) Light Ivory - daily driver
82 300D 166k mi (881) Thisle Green - fixer upper
82 300D 282k mi (473) Champagne - parts

Astute of sixto to request photos of chambers five and six. The pattern of residue on that number five chamber is not good. The residue should be basically spread more evenly rather than only on the one side. If not a crack between the pre chamber and valve seat I do not know what it could be.

Everytime I hear or see problems like this it makes me want to shy away from those engines. There is akways a conflict though. I would also like the additional power they can produce. Old story of I want my cake and eat it too I suppose. Too bad if it is indeed a crack

I'd send it out to Metric to have it checked over and freshened up. No point in putting it back on if its cracked.

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2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Any contact info for Metric?

Ask for Mike.

http://www.mercedesengines.net/

Tell him I sent you..........and you're from M-Shop.

Agreed! Tons of quality ideas and analysis in this thread in just a couple of hours. Man, I love this site.

Thanks, everyone!

Well done!

I agree.

#5 is cracked between the prechamber and one of the valves. Typical failure point. Sorry........it's not fixable without a replacement head.

Brian,

Are you talking about the chip at the 2:30 position of the intake valve? I didn't see that until taking a close look at the close-up. I believe there's a cooling jacket in the head between cylinders.

Sixto
87 300D

Here's what I'm looking at.........between the intake valve and the prechamber.............and I believe it is definitely a crack:

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Umm... isn't the smaller valve the exhaust valve?

This is the other crack I see...

Sixto
87 300D

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Yep........sorry.........exhaust valve is correct.

That one is less of a certainty..........cannot tell from the photo for sure.

Confirmed, 5 is definitely cracked between the prechamber and the exhaust valve. I can just about get a fingernail in there.

Not sure about the other one though.

I sent an email to Metrix about a replacement head. Stay tuned.