I learned this the hard way. The top hose of the expansion tank butts up hard against the inlet/outlet of the oil catch can. The hose has to be forced to connect to the expansion tank which doesn't end up seating well. This caused 240 degree coolant to blast out of that hose and left me stranded on the side of the highway with my 2 young kids. This was not an issue with the OEM plastic expansion tank. Let me know if you have any questions.