It sounds like the injector cups are bad Had the same thing happen last summer, fuel and coolant trying to change places. Injector cups and the head was cracked to verify drop the oil pan and then pressure up the system look up in side while it is pressured up you should see where it is coming from you of course have to use a flash light.
Anything else it could be other than injector cups or a cracked head? How long do you think I could run it before making repairs without totally blowing the whole thing?
Have you heard of this "Power Cool Need-Release Cooling System Treatment" system?
The more you run it the more damage will happen i would not run it to long before getting into it.
The most common and likely place for fuel to get into the cooling system is from the injector cups. This is 99 % of time. If you have a DDEC 5 engine, this is pretty easy fix. The cups can be removed and replaced without pulling the head. If it is earlier then a DDEC 4, then the head would have to come off to replace the injector cups