[hunter4ever12]

So I have a 94 Chevy k2500 with the 350. As the title States it overheats when temps are below zero. It was -16 degrees this morning here in Colorado. I have a magnetic block heater for it on the oil pan that I plugged in last night knowing it was going to be this cold. Went out and started it this morning to let it warm up, it idled for about 15 min and when I went outside it was still blowing ice cold air. I took off and drove about 5 blocks and noticed the temp gauge rising alot faster than normal yet my heater was still blowing ice cold. I knew something was up and turned around and headed back home. By the time I got home the temp gauge was in the red. I popped the hood to find that no coolant was flowing. The overflow tank on the passenger side was still on the cold mark and no coolant had flown into it. I shut her down and hopped into my blazer and headed for work.

So a little history on the truck, I did delete the pre heater hose, flapper, and baffles on the stock air intake to make it more free flowing and a true cold air intake, (that's why I have the magnetic heater, to assist in warm-up on cold starts) I also did a complete coolant flush and thermostat swap(changed the stock one for a 210 deg one) about 3 months ago. After the coolant flush I put a 60/40 mix of antifreeze water back in it. I also previously owned a 92 Chevy k1500 with a 305 and all the same mods and had this problem occur with it once before as well. I am a bit stumped as to why this is occurring and I have now had it happen more than once with two different vehicles. I personally think a 60/40 mix should not freeze the coolant in the cold temperatures we see here in Colorado, am I incorrect? I obviously know something isn't/wasn't right but I'm not sure what. By all logic I believe this should not be happening. Any help is appreciated.

Thanks,
Wesley