How much water is too much water?

So it’s been raining here recently cats and dogs just about every day and I noticed that I got a couple drops of water into my pressure washing pump from the vent hole…its literally like 5-6 drops… if the pumps been sitting still you could see it separated out but the second I fire the thing up the oil gets milky as its mixing the water with the oil… the answer is change it yes I know…i just have had zero down time… my question is how detrimental are 6 drops of water to my oil? Is it a life or death of the pump situation or can I wait a couple weeks until I have a down day??

Are you sure the water came thru the vent hole? 6 drops of water sounds too little for the oil to turn milky… It could be you have leaking seals and they are leaking into the crankcase… Also vent holes are designed in a way that water is almost impossible for it to enter unless the pump was submerged.

If it did enter thru the vent hole like you say it did, Just drain the oil and no harm done… Just don’t run the pump with water in the oil for a long period of time, it will cause excessive wear to the pumps internal components…

1 Like

It only turns milky when its running…if it sits for a half hour it separates out… I’m hoping seals aren’t going bad already this thing’s brand new I’ve only had it like 3 or 4 months…and it doesent get beat on to bad… I run it for about an hour and then it cools down for about 30 minutes and then I run it for about an hour and then it cools down for 30 minutes… and I do that about three times a week

1 Like

What pump is it?

My Cat 4/4200 pump oil would get really foamed while running, even after I changed the oil. It eventually turned clear in a couple hours after I shut it off.

Now the oil on my new belt drive GP stays clear, not sure why. Anti-foaming agents I guess.

1 Like

Trust me you WILL have down time if you let the issue dwell. Your equipment always comes first priority. Upload a photo of what you mean by milky. Sometimes the vibration of the machine might make the oil look different.

1 Like

If your pump is leaking from the inside, your sight glass will get full and come out the top eventually, I had a filler cap go bad once. Change oil with 30w NON detergent oil…Go back to business,put a pale over filler cap when it rains to see if that’s the problem

1 Like

Oil is cheap compared to a new pump. Make time to change it or your pump might make the time for you at the worst possible moment.

1 Like

I’d say the milkiness is mainly from it running. I doubt a 6 drops of water is going to hurt anything but I bet there’s more in there than you think. Even if it was only a few drops I’d sleep better knowing there wasn’t any in there. It only takes a few minutes to change the pump oil. You could even pull the drain plug before bed, let it drain overnight, and get up 5 minutes earlier to fill it. Plus, get it changed and then you’ll know if you have a slow leak from the seals. If it is you’ll then be able to prepare for downtime by either ordering a rebuild kit and planning a day to do it, ordering a spare pump, or getting a mechanic scheduled and ready for a certain day.

I agree with what @Bear said above. Equipment needs to be a priority. Let things slide and you’ll end up being down for a week instead of the few minutes it could’ve taken to do the maintenance. When it comes to pump and engine lubrication it’s not worth pressing your luck.


I had the same problem years ago. Change it, run it for a few minutes and change it again. If you only drain it once sometimes a little residue will make it milky again. You’ll think you blew a seal when it’s just a little water still inside. I also read here before that moisture and humidity get through those cheap filler caps and cause your problem. It was for me.

1 Like

What my local mechanic suggests is to drain then fill with a cheap thin oil like mineral spirits and turn the engine over a few times then drain and refill with pump oil. Do not run run the engine with mineral spirits in the pump.


It’s a comet belt drive

I’m definitely changing it !!!
I’m not going to wait for something bad to happen.

1 Like