Why Is There A Small Hole In A Water Pump?

I've got a small unplugged hole in the front of my water pump. What's up with that? Have I lost a bolt or something? Should I plug it up with some sealant or screw a bolt in there or what? Not to worry. Here's the skinny on that little hole in your water pump.

Water pumps all come with a hole in them. The hole is called the "weep hole". It's not that water pumps are naturally sad or anything. They need the weep hole to warn you when seals are about to fail in the pump. The weep hole is intended to allow extra lubricant from the pump bearings to drip out of the water pump housing. Without this hole, the oil would be forced past the water pump seal and get into the engine coolant. The hole also allows coolant to escape the pump housing instead of being forced past the oil seals to contaminate the bearings.

The way you can tell if a seal if about to fail is by checking the weep hole to see what is coming out If oil comes out of the weep hole, it means you have a blown or failing oil seal. If, instead, water or anti-freeze leaks out of the weep hole, then you have a leaking internal water pump seal in the case. Small amounts of moisture or oil around the weep hole is probably not a problem, but if there is significant leakage of water or oil, it's time to replace the water pump.