Alright guys, I've looked everywhere and cannot find the answer to whats going on with my motor. Around 255,xxx it started burning oil, bone stock motor. I pulled the motor and did a oem spec rebuild. Had the block honed, head and block resurfaced, the normal stuff. Got it together and dropped in, ran for 550ish miles, all freeway. Then i was idling in my driveway, it just cut out on me for no reason. I started it back up then bam, theres the white smoke. Tore the head back off and all cylinders had coolant in them. The coolant also mixed with the oil in the crankcase, which i heard was rare. Figured bad head gasket, took the head back to the machine shop, no cracks all good. Built it back up this weekend and started it today same thing, white smoke out the exhaust. Head is good, fresh head gasket, arp studs, pistons look dry through the spark plug holes, everything done right. Im at a loss here i have no idea. If anyone has seen this before please give me some insight.

Thank you.

 

No cracks in head, how about block? 94

 

I've seen a few where the head has a hairline crack in the port behind the valve that can be very hard to see. Best way to check for this (can be a little bit of a pain) pressurize the cooling system, remove the intake manifold, header and valve cover and look to see if you can find a coolant dribble