Replaced my Behr radiator on my e39 M5 with a Nissen today and everything is pretty exact. Only issue I am having is the o rings that came with the Nissen. I put them on and the radiator hoses will not go on far enough to push the clip on. The old one did not use o rings and it feels the same as the new when the hoses are attached. I dont want to waste coolant to find out they leak, is pressure going to prevent them from leaking thus pushing the hoses back and sealing the gap if there is any? Other option is to find a o ring skinnier in size but same diameter. Any one run up on this problem?