Hi! Have a strange problem, the coolant reservoir is always empty, seems like the coolant flows through the oil seal behind the water impeller. The strange part is that almost no coolant flows out here when the reservoir is empty.. The waterlevel in the radiator is decreasing but i can ride 400km without the waterlevel getting to low in the radiator.. So I figured maybe I should try to replace the oil seal behind the waterimpeller.. So I removed the waterpump housing and it seems to me, from what I can read in the ownersmanual, that I have to hold the impellershaft.. Meaning i have to do a lot more disasembling.. So my question is: Is there a problem with just putting the engine in 1stgear and and screw the impeller of without holding the impellershaft? And second, wich way to screw?