2003 R50, I’ve just replaced clogged heater core/matrix and these blasted clamps are a pain. I used a bit of Vaseline and got the pipe flanges nice and tight (or so I thought) but the clamps are so narrow they seem to barely cover the flanges. It’s all buttoned up now but I can hear a faint hissing during test drive. Any tips for getting these things together? Or any diy alternatives to terrible oem clamps?