Milkshake Oil mixing with coolant after drilling exhaust hole to helicoil/tap.

[Mustangk]

So my question is what i need to replace to fix this and how to drain the engine and intake and exhaust or whatever is contaminated with this milky milkshake. i drained it all right after it happened and filled with new oil to drive a block home from where i noticed a problem.

So how i think when i was drilling out an exhaust hole for a helicoil i used too big of a size or went to deep on the drivers side second from front exhaust hole. I was using a m12x1.25 size helicoil and cooresponding drill which is alot larger than stock m8x1.25 hole size.

After succesfully getting the helicoil in there i had coolant leaking out of the hole and couldnt get the bolt tight enough to seal the water jacket with the bolt and then all of sudden oil started to mix with coolant. Did i drill into the coolant jacket and oil gallery so coolant gets into the crankcase or oil passages ? or whats going on most likely.

coolant was barely dripping out the exhaust bolt i fixed so i took it to gas station for some cigarettes and thats when the milkshake fluids mixing happened

 

[msvela448]

If the helicoil was in a lower hole, then you are likely in the water jacket. Remove the head... Weld the hole, if possible, or replace the entire cylinder head.

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[RED09GT]

Without seeing it, I'd say replace it.
You'd need to have it welded back shut, drilled out again for the bolt and then you might need to get the flange surface machined flat. You might get lucky but the chances of having the costs snowball are high on this one.

 

[Mustangk]

so far so good. cross my fingers. replaced head with what seemed like a good head from an also good block from junkyard, also reused my mls gasket(i believe, stocker), and doesnt seem to be leaking at all, compression showing right at 185 across all 4 cylinders!

taking alot of oil changes to get all that water out though, im on oil change number 4 with about 200 miles driven to heat up the crankcase between the 4 oil changes. Still a little water comes draining out the drain plug first right as i crack it as waters heavier than oil.

flushed cooling system with a pressure washer on low and some squirts seems to be free for most part of oil, ill keep flushing it a few times here and there, alot less worried about cooling than the oil system, as cooling i can manager with the heat gauge, i need an oil sandwich adapter with pressure gauge tapped in.

 

[Mustangk]

If the helicoil was in a lower hole, then you are likely in the water jacket. Remove the head... Weld the hole, if possible, or replace the entire cylinder head.

it was the drivers side(bank2) head 2nd bolt/stud from the front of car. genius me thought i could tap the whole out to around 1/2" after failing to drill straight holes at the smaller variations between m8 and 1/2", ended up drilling into the crankcase right next to the valve spring which also i think drilled into water jacket underneath so oil from crankcase once pressurized all just poured down there or something.

curious if ^^water^^ leaks into >> |oil| OR |oil| leaks into >> ^^water^^ when theres a hole where they would clash into each other? you wizards must know. one of you wizards.