That's the problem and I think the only place coolant can leak to gearbox is at the waterpump axle. There should be somekind of O-ring thats propably worn? Is is possible to fix it without having to remove the whole sidecover of the engine? Is it enough to remove waterpump cover and waterpump and change the sealing(O-ring) through that? Also if someone knows if coolant an leak to gearbox any other way please tell me.