So, I’ve been given an older Mitsubishi Excavator. It’s a 120 I believe. It’s been sitting for 6-7 years. All 4 cylinders leak & im planning on removing & have fixed over the winter. It only has 3800 hours on it & I know it’s correct as guy bought it new. It’s my neighbor & I remember when he brought it home. The Hyd. Fluid was very milky. Everything worked well. I changed all filters & drained tank. Refilled. Still very milky! Could a guy flush system with diesel fuel a few times or would that cause pump problems? Hyd. Fluid is a tad pricey to keep adding & dumping. What’s best way to flush system. I like this rig. It is old but will see pretty easy duty by me. Thoughts?
You'd never get all the diesel out without taking it apart, and then you might as well do that to get all the oil out. There are ways to remove water from oil, boil it out, vacuum dehydration, absorbing filters, centrifuge. I've wanted to rig up a water heater tank with a vacuum pump for this purpose, but haven't gotten it done. Suck the oil into the tank, heat it to 180 under a moderate vacuum, return to the machine, run, repeat until you don't get more water.
See if you can rent a filter cart with a filter for water. Donaldson has filters to remove water. I don't think I'd want to run the milky fluid through the entire hyd. system if I didn't have to. Might have to do it a couple times. Need to find out how the water got in so it doesn't happen again.
This looks like the best solution if one is available in your area
Good day I suggest you take the long hard route remove clean and inspect all the components water will cause irreparable damage to those expensive hydraulic components, I have no experience of the Donaldson system but it would be tricky to get all the water out. Kind regards Uffex
I think what you'd have to do is a kidney loop to run the oil through the filter cart and back through the reservoir several times to flush and filter all the water out. Then when the oil looks decent, start the machine and get it to operating temperature and run in through the filter cart again to get any left over traces of water. Some lines you'd want to disconnect and just drain the milky oil.
I’ve just been through the process of purging the hydraulic system due to milky oil as you describe. I would suggest you do it the same. I drained the tank, scrubbed it clean, cleaned suction strainer, replaced all filters and cooler hoses. Removed cooler, cracked lines to travel motors, cracked low lying lines such as to swivel etc. everywhere I thought would drop oil. You’ll be surprised how much the cylinders take, so if your taking them off for repacking then you can drain them all. I let sit draining everything for a week and got 280l (~74 gal) when book suggests 200l per service, I failed to factor in this additional amount when purchasing oil. I left return to tank lines open when topping up and poured oil down tank inlet thus purging return lines of additional milky oil through gravity. After topping up and running the machine there is a hint of cloud to the oil which out of the drum was clear blue, it’s very faint though. I think it is nie-on impossible to remove it all save cracking every line.if it’s been sitting for that long I would recommend replacing the tank outlet hose to pump and the clamps with good quality new ones. Don’t forget to prime the pumps before restart and go through the process of Clearing the system of air.
Wot he said.........
If adding oil is pricey, tearing the complete machine down for inspection is a major operation, especially for someone who isn't experienced with it. The milky fluid has already been run through the system. Removing and cleaning what's relatively easy and draining hoses then running the fluid through the filter cart several times may be a good compromise. A filter cart is good for new fluid as well. 3800 hours means nothing if the hyd's are compromised. It might as well have 20,000 hrs as far as the components go. Is your neighbor giving it to you or are you considering buying it? If you have to buy it, it would be best to establish a price and see if it's even worth tackling. To have a shop go through everything would cost thousands of dollars. If you do it yourself would take a considerable amount of time and likely be very frustrating on some things. Having the cylinders done could cost a few thousand dollars depending on what shape they are in.