So i have a transmission cooler that needed to be replaced due to a rock cracking the hell out of it on a freeway. I ended up replacing the cooler and put everything back together like normal; nice and tight (fan, radiator, shroud; keep in mind I had to drain the fluid out of the radiator to get it out.) now I put 50/50 mix in the coolant reservoir system and i let the engine run and it quickly sucks all of the coolant down after I turn the engine off. I had heat on blast but I noticed there was 0 heat actually coming through so that was a problem. I drove the jeep the next day with another 50/50 mix and I get the 'check gauges' light and red lining. I'm confused. The coolant which I had put in was also sucked dry, do I just need to keep adding more coolant until it stops constantly draining? No leaks or anything.
Sounds like you had an air bubble trapped, making it appear as though it was filled. Once you got up to temp and the thermostat opened, the coolant started to flow through and burped the air bubble out. Assuming there is no coolant dumping out somewhere, you should be good to top it off now. If it was terribly low, you wouldn't get adequate heated coolant through the heater core, so no heat coming from the vents. It would also allow the engine to overheat.
If someone used a non-vented t-stat in your jeep it can get a big air bubble trapped until the engine gets hot enough to cause it to open. The catch is with no coolant up at the housing, the t-stat is only heated via metal conduction. You can overheat pretty severely before the head heats the aluminum housing enough to start to open. I've seen this on three jeeps with a 4.0. The proper t-stat has a small hole (often with a little loose plastic button in it) that allows air to vent to the upper radiator tank even when the engine is cold.
Btw, how much coolant did you add? It should take a little over two gallons to properly fill the radiator and overflow if the radiator's been pulled. A bit more if somehow the block below the waterpump was drained too.
Good news is, if it was due to a trapped bubble, your heating and re-filling should have purged the air pretty well. At least until the next time you drain your coolant...
Horse: the original off road rig.
Jeep: just as fun and no stall to muck.