LMM coolant in oil

[wpenner]

Needs some ideas what can cause coolant in oil. Already eliminated water pump, oil cooler and turbo. No combustion/compression going into cooling system. Have the bottom oil pan removed and it's seeping in around cylinder 4, pressurizing cooling system to 10-15 psi. Would a head gasket leak but only coolant into oil?? No injector cups on a LMM. What else to check before I tear it down.

Engine is built, has arp head studs. I think it has around 60k on the engine, maybe 80k .

 

[TheBac]

Moved to LMM section

 

[JoshH]

Could be a cracked cylinder.

 

[wpenner]

Yes its a crack. I was able to snake a scope up the bottom (not the best quality). Crack is at the bottom of cylinder 4. Any input on cause? Max tune hp 750-850. It is bored 20 over.