Hello everyone, about a month ago I bought a Gx390 w/ a 4gpm CAT 45G pump used from someone who said they owned a construction company and used it to remove graffiti. I live in Ohio, it was stored in a storage unit, and all the gas was emptied out during/before storage.
I had just redone all the fluids on it (engine, pump, gearbox with all their respective oil types) and replaced carb (it was leaking and wasnt the needle valve or float bowl gasket so i just put a new oem one on), replaced fuel lines, and put a new QC on it. I decided to finally test it today. I ran water through it and water started shooting out of the thermal relief valve. Before spending another $60 and more time on it I wanted to see if the pump even worked so i started it and shut if off after i saw i was getting pressure. This is when I noticed the milk in the pump oil and gearbox (it could have been there after water, but before i started it; i am not sure). I was/am beyond disappointed. Did I goof by running it with the thermal valve popped, or was something wrong from the get go? Iām not sure what caused this but Iād love to hear if anyone has experienced this. Is it just the seals? Could it be something more? How big is the chance I spend more money to get this fixed by a shop only to have more issues to deal with. Basically Iām asking is do you all think its worth it to dump more resources into it, or should I just slap a new gb and 5.5gpm pump on it (money I really thought I wouldnāt have to spend, at least right away)? Iām so torn and saddened as I was really excited to get started washing. Iāve read so much on this forum (before making an account obviously as its fresh) and was just started to get confident about getting into the business, then this roadblock happens. I know Iāll encounter many roadblocks, but could I get some input on this one? Thanks a lot in advance everyone, I appreciate your time.
p.s. I can only upload one pic as a newbie, this is of the gearbox, but there is some milk in the pump too and the thermal relief valve is a hypro 3312-0004 145 degF
Youāre sure that itās milky with water, right? Gear oil aerates very quickly and sometimes itāll look like thereās water in there but itās just aerated oil. Let it sit for a while then double check. Pull a sample and put it in a glass jar to see if it separates out if you have to.
The thermal relief valve leaking isnāt ideal but also no big deal if youāre going to plumb the machine to a buffer tank. No need for a thermal relief valve if the machine is constantly circulating cool water through the pump and back to the buffer tank when in bypass.
Thank you Texan, I will check in tomorrow and see if its still milky. Well, the plan was to run it straight from the spigot for a little while with the 4gpm pump on it then either A. when I get a 12v pump to do roof washing with a blend manifold or B. when i upgrade to a 5.5gpm pump on the machine (using the existing gearbox) or 8gpm machine: iād plump into a/the buffer tank. Please pray its just aerated oil, if so iād be tempted just to plug it and be sure to be on the gun every 5s or less (who am I kidding, Iād probably take the safe route and buy the valve just in case thereās an unloader issue). Iām really hoping its aerated oil and youāve got me tempted to go out to the garage and check, but I think I will update you all tomorrow. Also, the valve wasnāt leaking so much as it was shooting/spraying/gushing water out of it (with the machine off) I was thinking to myself that had to reduce flow to the pump, although now that I think about it iām sure it wouldnāt shoot that much water out of it if plumped to a buffer since there wouldnāt be the same amount of pressure as would exist from the water mains.
So both the sight glasses (pump and gearbox) looks normal now. If there is water in there Iām assuming it went to the bottom, although the levels look right so Iām hoping that means nothing got in. Iāll pull a sample and test
edit: Does this happen all the time? Why did the oil aerate? The milky oil probably doesnt lubricate as well, right? Whatās the deal with airplane foodaerated oil?
If you have water in there mixing with the pump oil and making it appear milky, itāll stay milky. Since it sounds like yours is returning to a normal color and normal level, itās likely that you are in the clear.
Eh, aerated oil in a simple gearbox isnāt going to cause any premature harm or anything. Itās pretty typical with the vibrations. You can take a sample to verify but Iām confident that itās just aerating the oil and since you say the levels havenāt changed that pretty much confirms it.
Yup I took a sample and let it sit for a few hours, no separation, nothing. So this is basically a non-problem and i should either A. replace the thermal relief valve, or B. set up a buffer tank and plug where the āvalveā used to be? the aeration was also seen in the pump watch glass, is this a normal thing? I apologize but itās had me quite a bit freaked out. Thanks for your responses DT, as well as PPWofLexSc, I appreciate it.
Yes, perfectly normal in the pump as well. This is why itās critical to use the proper oil for your pump. Non-detergent pump oil clings to hard surfaces very well and does so even when aerated.
Iād probably remove the āAā option and just go ahead and plumb up a buffer tank. With a buffer, you can let go of the trigger and move hoses, brush a gutter, tank to a customer, etc. You can do all those things without a buffer but youāll need to be squeezing the trigger at least every 60 seconds and holding it for 10-15 seconds to allow some fresh cool water to enter the pump. If youāre not squeezing the trigger every 60 seconds youāre going to eventually burn up the pump internals and that gets expensive. A 65 gallon leg tank would be sufficient for a 4gpm machine and thatās only a couple hundred bucks.
If (I probably will) I go the buffer route right away Iāll use a 55 gal plastic drum similar to those that come filled with bleach. Has anyone hooked those up together using a T at the bottom? Iām hoping to use that as a cheap 110 gal buffer tank when i upgrade to a larger machine. IBS my machine has rubber feet on one end and no-inner-tube tires on the other end. One tire leaked when I bought it so I filled it with about 6 oz of tire slime and no more leaks since. Here it is before I cleaned the exterior
-edit: semantics
Personally, Iād avoid the drums as a buffer tank but do whatever you have to. Theyāre just awkward to secure and I donāt like not being able to see how much water Iām working with. I guess you could try to find a couple natural colored drums but that might prove difficult.
