Black oil in 5CP2120W

[APW]

I change the oil once a year in my SS pumps. The oil out of the first pump was black, what would cause this? The second pump was milky, condensation or does it need a seal kit? The other two were good.

 

[MEP001]

Black oil is caused by wear. The connecting rods are aluminum wearing on a hardened steel shaft. Keep an eye on it and if you can remember next time you have the head off see if the plungers move in and out. It's possible there was moisture in the oil which has evaporated out. Milky oil is either water or the wrong kind of oil. If you're using Cat oil, it's water. They don't always drip water if the plunger seals leak - I'd recommend changing them along with the rest of a seal kit if it's been a while. If there was significant water in the oil, change the piston oil seals too.

Check the pump oil weekly. It's important to catch water in the oil early. The site glass unscrews for cleaning if it's dirty on the inside.