Pressure Washer Pump Is Leaking Oil – Why?

Okay so, let’s say that you have a pressure washer in the garage, and you decide you’d like to start a small auto detailing or mobile car wash business. First thing you need to do is make sure that the pressure washer is in working order, as after they have sat for quite a while, there is some preventative maintenance you need to do so that you do not damage it.

Let’s talk about this for a moment shall we? First you must check the oil, and make sure that the pump is filled to the proper levels. You can do this by looking through the eyeglass whole. Before you start the pump, you need to also make sure that the inlet strainer is attached so no debris gets inside. Not long ago, I was reminded of some of the challenges which come about when restarting old equipment. Someone had asked me the following question;

“My CAT pump just basically stopped pumping water. I noticed it was low on oil. I filled it to the required amount last night. When I woke this morning the oil was all over the floor of the garage. Does that mean maybe a blown gasket or seal? If so, can I fix that myself? Where is the best place to buy parts without having to pay $125.00 and ordering them from Italy?”

There are two things which can cause the oil on the floor, one is that you over filled it, that is easy to do, and that may be the problem.

If the oil is foamy, (A) then you have a blown seal inside, if it is leaking from the seam (B) you have a blown seal outside; if it coming out of the filler air hole (C) you put too much in.

If A or B you will need new parts, if (C) then NO. Most of those kits are for the valves, most likely those are fine unless you melted them or ran it out of water too long. They say CAT Pumps have nine-lives, so chances are your pump is still good.

It is entirely possible that there was a temperature change in the garage overnight, and that the pump was over filled with too much oil, as the pressure changed inside the chamber the excess oil was forced through the little hole, which is used for air pressure breathing in the event of wide swings in barometric pressure, or if the pump starts to overheat. In essence this is a safety valve scheme using a little trick widely known in physics. Indeed I hope you will please consider all this and think on.