2012 V8 5.7L Hemi, eagle heads - Blown Gasket or Cracked Cylinder head?

[hoze77]

I have a 2012 Jeep Grand Cherokee 5.7L Hemi (Same Engine as the Dodge Ram)
Issues:
1) Had multiple misfires, rotated the spark plugs and coils but didn't seem to fix the problem with it rotating to different coils
2) Engine overheated later that month, and oil seem to have mixed with coolant looking like thick chocolate milk, but more yellow and thick, not like some videos of it looking like Cream color milk shake. It came shooting out of the Coolant reservoir and radiator cap. It's Oil in the coolant, but no coolant in the oil.
3) Used the engine block tester and the liquid turned yellow, but took awhile for it to show up as I waited to heat up and thermostat to open and right after it showed up the engine got hot and starting shooting out the chocolate milk again. But the directions said it would show up right away, so maybe did the test wrong?
4) So we decided it must be a blown header gasket, so we started taking it all apart. Finally got the headers out, but didn't notice anything out of the ordinary, no shiny heads or clear signs of cracks?
5) As of right now I plan to buy new heads and head gaskets, as the price is actually cheaper than going to get my heads cleaned and machine scraped, but I'm scared that it might be a cracked engine block and will do all this for nothing?

Any recommendations?

 

[rzr6-4]

You probly needed to do the test on a warm motor with the coolant circulating. May not have had enough combustion gases coming through your static coolant until the thermostat opened up, which is when you finally got your positive result.

If you have that much gunk shooting out of your motor, it should be pretty obvious where its coming from. If its coming from the area where your heads mate to the block, then the gasket and warped heads all come into question, even if they don't look bad. Hard to imagine a crack somewhere else that would allow oil and coolant to mix, without just causing a catastrophic failure.

P.S., you aren't buying new "headers and header gaskets", you are buying new heads and head gaskets. Headers and part of an exhaust system. Heads go on your block.

 

[Racerhoze]

Testing on a warm engine was not possible since it started pushing oil emulsified in water out of the radiator. I ran it from cold for about 14 minutes and the positive was only moments before oil and water were pushed up into the tester. There are no external leaks on the engine at the gasket mating surface.

My thought is that somewhere in the head or block casting there is an imperfection or crack on the high pressure oil side allowing oil to be pushed into the cooling system. Where the high pressure oil comes through the head gasket it doesn’t make sense that it would fail all the way to a coolant passage and not anywhere else. There are no visible signs of failure on the gasket or surfaces.