Just finished the back to D-series swap in my EK hatch. We took it for a testdrive, got a half a mile from the shop and started loosing power dramatically. We turned around to head back and BOOOOM! Radiator has a 9 inch crack across the top plastic part. We took it back to the shop, took out the radiator, thermostat, coolant lines, and then flushed it out. Is there anything besides a stuck thermostat thet could have built up so much pressure in the coolant system? I dont want to just replace the radiator and Thermostat and have the same thing happen again. BTW, Im pissed off.

 

the only thing that would have built up pressure in the system would have been a giant restriction in the outlet side of the radiator or the pressure cap was way too high for that application