I have one of the first 185 engines and it has the nipple on the pump but it is simply disconnected as there is no nipple on the engine case to connect the hose to. Crankcase pressure was used as reference pressure on the earlier engines, on the 185 this is not done anymore, if it is not vented then it will cause an air lock which will add to the spring tension, so probably capping the hole will hide the real problem as the air locked inside will be compensated by the pump adjustment, I mean, the pump action will vary a lot if plugged and unplugged with the same adjustment.

Regards