pressurizing coolant

[Ruan]

Just do as I said, as long as the heaters stay hot, it's not SPRAYING out the rad cap when it's running... It's probably fine - pressure is normal to build since water expands as it gets hotter - also pressure is meant to build in cooling systems as it is more efficient at higher pressures, it also causes water to boil at higher temperatures, meaning you're less likely to boil water off in local hot spots.