CHANGING HYDRAULIC OIL WITH LOADER ON.

[downslope]

I have to change the common sump hydraulic/trans/diff oil in my tractor. I have confirmed there is some unknown quantity of water in it. Right now the loader is installed, but I will be removing it very soon for field work and it probably won't go back on until fall unless a special need arises.

Question: Should I remove the loader first and then drain the oil, or should I first contract the cylinders all the way and drain with the loader on? Of course there would still be oil remaining on the other side of the double acting cylinders. When the loader is removed and on the parking stands the cylinders are not usually fully retracted.

The thing is I would like to have the least contamination of the new oil as possible from the oil in the loader cylinders going back into the system. What is the best way to do this? The loader is a NH 820TL.

 

[gwdixon]

Try raising the bucket to its full height and the bucket on full curl. Then drain the hydraulic oil. After that lower the FEL boom halfway (tractor OFF!) and move the bucket to full dump about halfway down. Then lower the boom the rest of the way down and try to curl the bucket as much as possible when it is on the ground. Pulling the tractor rearward may better allow this.

Since the pump is not on then the oil on one side of the cylinder should drain and the other side will not have oil pumped into it. That is about all you can do.

When refilling and before removing the FEL you could buy some cheap hydraulic oil and fill with that. Then flush the cheap oil out of the whole system to further dilute the contamination. Put in quality oil and give it a go.

 

[downslope]

Thank you for the advice. Do you think the bucket will want to go to full dump with the engine off? I guess I can try that first to see. I can replace the bucket with a set of pallet forks, that might make it easier to dump and then push it back to full curl; what do you think?

Your flushing sounds like a good idea, but to fill the system takes 55 quarts. Even cheap oil is probably $40 a pail. I have 2 new 5 gal buckets of NAPA straight hydraulic R/O laying around that I could use for flush but I don't know if 40 quarts would be enough for the pump to pick up and work the hydraulics. I also guess it wouldn't cause any harm to the wet brakes just for a flush.

The 3-pt I should do the same, let it all the way down, right? Do you think I would get much oil out of the loader hoses by removing the quick connect fittings and letting the hoses hang down or maybe pushing the balls in and see what drains; probably not worth it?

Thanks again for the help.

Try raising the bucket to its full height and the bucket on full curl. Then drain the hydraulic oil. After that lower the FEL boom halfway (tractor OFF!) and move the bucket to full dump about halfway down. Then lower the boom the rest of the way down and try to curl the bucket as much as possible when it is on the ground. Pulling the tractor rearward may better allow this.

Since the pump is not on then the oil on one side of the cylinder should drain and the other side will not have oil pumped into it. That is about all you can do.

When refilling and before removing the FEL you could buy some cheap hydraulic oil and fill with that. Then flush the cheap oil out of the whole system to further dilute the contamination. Put in quality oil and give it a go.

 

[Soundguy]

here's what I'd do if I wanted less contamination.

add in a quart of 90% rubbing alcohol, a quart of diesel and a quart of type f or dex/merc3 atf and then run the system, including the loader thru it's paces to mix the oil. that means extend and contract each cyl many times.

then drain the sump.. then pull the hoses and blow them out with air to drain them. then pull the rod pin on the cyl and expand and contract it to flush it. ( an air line and adapter tips can help you do this via air pressure )

this will get almost all the oil and water out of the system.

Now, add the new oil and dump a pint or 2 of 90% rubbing alcohol into it and take the next half hour bleeding the system..

 

[k0ua]

You might try this.. (not that the other ideas were bad ideas).. there are 7 hoses going to your FEL valve.. identify the 4 work ports, that leaves 3. One is fluid flow from the pump, one is power beyond go ing back to the distribution block to supply flow to the 3pt and any rear remotes you may have, and the last one is return to tank.. That is the one you want to take loose, and dump the hose in a 5 gallon bucket, and tie it in so fluid flow will not blow it around. Change the oil, and refill Start tractor, as soon as you operate the lift/lower and curl/dump circuits the old fluid in the opposite sides of the cylinders will come out the return to tank hose. Operate until some amount of fluid is in the 5 gallon bucket, say a gallon or two, or until you notice the fluid clearing up some. Shut off tractor and refill sump. Dump out the suspect fluid and start with a clean bucket, repeat and examine this new fluid. Is it clean.? Either dump it back or discard. You will likely need a temporary plug for the sump fitting on the distribution block to prevent leakage..

Keep in mind, I have not done this, but it "sounds logical" to me.

In an open center system fluid flows from the pump (orange marker) to the inlet side of the loader valve, and right back out the power beyond hose (green marker) to the 3pt and it dumps into the tank. But the old fluid will not enter this stream until you move a valve one way or another, and that waste fluid from the opposite side of the cylinders dumps into the tank down the low pressure return to tank hose.. The gray one on a Kubota.. I have no idea what the color code is on a NH, of even if it has one. All colors refer to the Kubota color scheme. Good luck.

 

[gwdixon]

Thank you for the advice. Do you think the bucket will want to go to full dump with the engine off? I guess I can try that first to see. I can replace the bucket with a set of pallet forks, that might make it easier to dump and then push it back to full curl; what do you think?

Your flushing sounds like a good idea, but to fill the system takes 55 quarts. Even cheap oil is probably $40 a pail. I have 2 new 5 gal buckets of NAPA straight hydraulic R/O laying around that I could use for flush but I don't know if 40 quarts would be enough for the pump to pick up and work the hydraulics. I also guess it wouldn't cause any harm to the wet brakes just for a flush.

The 3-pt I should do the same, let it all the way down, right? Do you think I would get much oil out of the loader hoses by removing the quick connect fittings and letting the hoses hang down or maybe pushing the balls in and see what drains; probably not worth it?

Thanks again for the help.

Using forks to help the bucket dump sounds like a good idea until the FEL boom needs to be lowered. The forks will be down and prevent it.

Yes, the 3PH should be lowered since it is a single-acting cylinder.

Wet brakes are a plus since most of the water will settle there. The wet brakes are usually the lowest point in the system. You might be surprised what comes out when those plugs are pulled.

My ideas were just for a simple drain of as much fluid as possible without complicated procedures. I'm sure that Soundguy and k0ua have more complete and efficient methods. It depends on how concerned you are about the issue and how contaminated the oil is. Only you can make those decisions.

Flushing was only a suggestion but I didn't realize you were dealing with 55 quarts. My M7040 and L48 use 15 gallons (60 quarts) each so I can relate about the expense.

Hope it all works out for you.

 

[Soundguy]

you were dealing with 55 quarts. My M7040 and L48 use 15 gallons (60 quarts) each so I can relate about the expense.

Hope it all works out for you.

Reminds me of a funny story.

Guy was changing the hyd fluid on a NH7610s tractor ( 13-15g ) and had a few 5g buckets lined up and as he sat under the tractor, got the drain plug out, filled a bucket, then he would thread the plug back in a bit and carefully slide the 75%-80% full bucket over and slip a new one in place, then repeat the procedure.

Poor guy driopped the plug inthe bucket while trying to screw it in to change buckets... so bucket was 75-80% full already... not much choice but to try to plug drain hole with 1 thumb and then go fishing inthe bucket with other hand to find the plug, hoping the residual oil still flowing around thumb didn't overflow the bucket.

well.. I DID find the plug the 2nd bucket was fileld about 99% and neither of my arms had a dry skin problem for quite a while... had to eventually throw my shirt away.. .. though it did make a good rag to clean tools and water proof them for a few days prior to disposal.

and that story remonds me of when I installed a loader on my NAA. I was testing it out. still using the old hoses.. had new ones. wanted to get the laoder boom to max height to bleed it, then change the main feed hose. As luck would hav eit, main hose popped at max up, bucket hit floor like a brick exhausting oil in an instant, pump still going putting out oil. That was? 10ys ago.. tractor still won't rust! had to relegate those clothes to oil change clothes too! wife wouldn't let me was them in the house even.. had to toss them onto the concrete and power wash them then stick them in a 5g bucket with some simple green.. then hang out to dry... they never smelled the same again.

have fun! be safe!

 

[Zebrafive]

Glad I am not the only guy to ruin clothes with an oil bath.