Well, you may need to identify correctly what that liquid found in the hose is, if is "oily", that means that you have oil coming from the pump and that also means that you have a good chance that oil went into the Cactus Juice and spoil it, unless you filter the CJ with some coffee filters and see it water is present.
The most common reason this happen is when you have the oil sump level far too high, this will make oily fumes to come out of the pump breather but also allow oil to the sucked into the vacuum chamber, how..? when you are at full vacuum and turn the pump off without realising some vacuum from the chamber, what happens is, the suction power from the inside the chamber is sufficient to suck oil from the pump.
There is only one think that will prevent it and that is an electric non-return valve at the pump outlets HOWEVER, if you get CJ into the oil, that means that you have allowed the CJ to be sucked from the inside the chamber and yes, a compressor water filter system will prevent oil to get past that point unless the amount of CJ being sucked is enough to fill the water reservoir of the filter, in that case the CJ will continue its travel to the pump sump.
If this happen, you need to "flash" you system with petrol, from hoses, joints, filters and pump, after removing the contaminated oil, put the bleeder back on and poor some petrol into the top sump opening, put it back on and shake the pump the best you can, removed the liquid out and you can assist the cleaning by using the air blowing gun to blow air from that top opening forcing the petrol to come out, after that, fill pump oil to level (only), reconnect everything else and turn the pump for a minute, check if oil is still level or need a little more.
You can also use those petrol filters found in motorcycles, quads, etc., they will catch whatever comes into the pump or goes into the vacuum chamber, these are efficient for small "accidents" after the filter is full/soaked, the damage will still happen.
I have had all possibilities happening to me, more in the beginning but, the one that I could not control was when I have the pump/chamber at full vacuum and remember that I have a 16 litre capacity chamber and the power/electricity goes down and I'm not near the pump, the amount of sucking pressure inside that big chamber is such that, it will such half of the pump oil reservoir into the chamber, spoiling everything.
This has happened a couple of times before I found a similar type
vacuum pump that comes with an electric non-return valve, not costing me a fortune, in fact, the cost of an electric valve alone was twice the cost of these regular pumps, these pumps are installed with this valve from factory at a very affordable price, and everything has been working well...!
Hope this helps...!
Cheers
George
