Blister28

Ive drained the oil and have seen no coolant coming out of the threads of the oil pan or at all. Compressor was replaced by us two years ago. It seems to build pressure ok. The steam mostly come out when its under load and its in PTO. When it's idling out of PTO it's not as bad. (This is a concrete pump truck fyi) 

Ive heard that before it might be the compressor. But how would I go about checking that? Where would the coolant enter the crank case if it were doing that? the actual crank case breather has slow coolant drips coming out of the overflow tube as well as vapor.

We maybe add a gallon of coolant every two weeks. Yes we took the cover off and the valve train is squeaky clean. No Mayonnaise. 

So if it was a turbo wouldn't I get white smoke blowing from exhaust? coolant would leak into the exhaust then correct? how would I test if it is the turbo? It runs clean and has no smoke from exhaust. As stated before we dropped the pan and pressure tested it for two hours with no signs of coolant. 

Hey guys help would be appreciated! 

Truck blows coolant vapors out of the blowby and fill tube. It's definitley coolant and not blowby from the rings. Coolant slowly drips out of blowby tube after the vapor condenses enough. We took off the valve cover and oil pan and everything inside looked clean. No sign of coolant in the oil. We then pressurized the cooling system for a couple hours and could see no leakage around the liners or up on the valve train. We bumped the starter a couple times to put the pistons in different positions in the liners but still could see no leak. We have heard maybe an air compressor could cause this? How do we test that? The EGR had been blocked at the exhaust manifold so we are doubting it's the EGR cooler. Engine runs great, no smoke from exhaust. Obviously we are concerned. Any theories?

2013 MACK MRU with an MP7 motor. 

I started the truck a few days ago and noticed a lot of white smoke coming from the exhaust. Took off exhaust pipe at the turbo and started it it up again. Coolant and white smoke came pouring out. I shut the truck off and checked the dipstick. It was very full and very milky so coolant is getting into the engine. I dropped the oil pan and pressurized the coolant system and noticed coolant coming out of the 5th cylinder. I noticed dripping from the inside of the piston sleeve. It came down the piston and dripped off the wrist pin. It looked like the sleeve was fine with no visible cracks. I took the exhaust manifold off and looked into the exhaust port of the 5th cylinder, It was full of coolant. I noticed a tiny bit of what looks like maybe copper in the exhaust port. My guess is either a blown head gasket, or maybe an injector cup? I know the injector cups are copper.  I personally drive this truck every day and I know for a fact it never even got close to overheating. Even with coolant coming out of the turbo it started right up and idled normally.  After letting the truck sit overnight i tried to start it one more time to get a quick video but the motor was locked due to the cylinder being full of coolant i assume. I didn't keep trying to crank it out of fear of breaking something. So has anyone had this issue? Would you say an injector cup? blown head gasket? cracked head? The only Check Engine Light Code that came on was low coolant in the reservoir.