Final diagnosis...head gasket blown?

[Vanarama]

Hey guys,

Just want to confirm my diagnosis. Radiator blew a leak a few days ago and the van overheated. I found a leak on the radiator. Suspected a crack in the head gasket and pulled the spark plugs to inspect them. #3 had coolant on the threads. Should this 100% confirm a crack in the head gasket?

No milkiness in the oil and no white smoke coming out of exhaust. Just coolant on the one spark plug.

Are there any other scenarios to investigate?

Thanks for your help.

[kamesama980]

Could also be a cracked head or block.

Compression, cylinder leakdown, and coolant leakdown tests could also help pinpoint a leak vs spillage.

Could coolant have made it's way to the top of the engine previously from the radiator blowing and spraying coolant everywhere? Odd that it'd be an the threads but not the tip. Does that plug look cleaner than the others like it's been steam-cleaned? can you see the top of the pistons through the plug holes or get a bore-cam in there?