The bearing has nothing to do with weather except for the fact that in Quebec the salt on roads they put during winter doesn't help on parts longevity. The pump is actuated on startup depending on certain engine and environnement conditions, outside air temperature can be one of these, so if the outside temperature is cold for example, the pump doesn't have to function. If the pump doesn't have to function the bearing doesn't either, so no noise. I hope I got it wright. I still have to remoove the pump, I'm having trouble with the top allen bolt, looks to be a 4 or 4.5mm head. Bottom bolts are pretty tight too. I should get tools tomorrow and by wednesday have it out. Finding the bearing should be easy if I go to a bearing speciallist.
1973 porsche 914 2.0