We have a samsung lc3 excavator and the oil keeps turning milky. If you leave it sit not running for a few hours the oil goes back to normal. I had the Volvo dealer come out and look at it. He said pump was junk. So we put a brand new pump and coupler on it. Put new filters on it and new oil. It’s doing the same thing. Any ideas would be appreciated.
Did you clean the tank and dump strainer? Did you replace the suction hose from the tank to the pump? How about the vent valve on top of the tank, does it maintain pressure in the tank anymore. If you don't have positive pressure in the tank, it will foam. Did you service the return filter? How about the pilot filter and case drain? How old is the oil you have in it? I would hope you changed it with the pump, but I realize it's very expensive. The three biggies are, suction hose, strainer and vent valve. Start there. Good luck
I replaced all the oil when I changed the pump. I also replaced the hydraulic filter and the strainer. The vent valve on top of the tank has pressure when it’s running. I did not replace the suction hose. Is that necessary?
If it's not super soft and flexible with no cracks, I would say yes. That hose is everything to your pump. It carries oil from the tank, doesn't collapse, and seals 100 % at either end. I never replace a pump without doing that hose with the job. After 5 or 6 years they get stiff n brittle. The edges crack,sometimes the stiffener wire inside rusts and splits the rubber inside. Yeah, it's pretty important.
BTW, what was the Volvo techs justification for recommending a pump replacement? Was it low on power, slow or just the whole aeration thing?
He said the pump was way too noisy and it needed replace.
Wow, I'm sorry to hear that. I don't want to make you feel bad, but that tech is a hack, if that was his justification. That's like telling a guy with obstructed arteries, high blood pressure and pneumonia , that he needs a heart transplant. Take care of all the peripheral things first. Adjust pressures, verify flow etc etc. Pumps can whine a little with age, it's not ideal but ***!? I would never change a pump for some noise, unless it was shedding material, overheating or unable to achieve pressure and flow. I'd find a new dog, a little longer in the tooth. And I'd dispute the need for the pump. Especially if you still are with your original concern, noise.
The pump he said was bad was only 3 years old. The pressures checked out fine the only thing was he said it shouldn’t whine that much. And we were getting milky oil. New pump is quieter but same exact problem with the oil. Then the oil heats up and heats up the engine. I looked at the suction hose and only about 4” is rubber the rest is metal.
Iff your suction pumpe is on good condition and you have a positif pressure on the thank the first thing to do is Make sure all pressure setting is good , overload , 2 stage main relief valve , the proportional solenoid valve on the pump have a good setting .
Milky oil is water contamination. Foamy oil is aeration or cavitation. Both of which can be corrected without changing the pump. Get an oil sample, by a reputable lab. Use that as your baseline moving forward. If you aren't shedding material into the oil and not introducing water into the oil , and your cycle times and pressures are correct, you don't need a pump. You need to determine which is occurring, contamination or aeration.
Not sure about water , but I would expect aeriated oil to make a racket going through any pump . What oil are you using ? Is it milky before or after use ? Did you try draining a little from the tank in the morning ?
Could you have a leaking suction line that is letting air in?
You have to be sucking air. I would store the oil and once again remove the sump strainer, inspect and clean. Then I would pull the feed pipe off the bottom of the tank. It should be a bolted flange. With that off, I'd replace the connector hose and the o-ring. I'd replace the o-ring at the pump inlet flange also. When you have the big elbows off the tank and pump, make sure your o-rings protrude beyond the groove. They gotta compress to seal. Make sure you use constant force clamps on the hose joint. Don't use those cheesy hose clamps you would use on a radiator hose. Something like the attached image.