sometimes the hose becomes stuck on the radiator flange and or the waterpump, making it very difficult to pull or twist off. In that situation, you can use a knife to cut off the hose. You can use a box cutter very carefully to cut the hose lengthwise where it is stuck on the flange. If you do this, the key is to be careful to to gouge the underlying flange on the radiator or waterpump. One the cut is made, the remaining hose can be peeled off. I recommend cleaning the flange with fine grit sand paper so the new hose will have a clean sealing surface. I have used gasket sealant on the new hose to further strengthen the seal.