How to remove bad hydraulic fluid from detached frontend loader

[Mikey201]

Hello, I'm new to this site and am looking for some help!

My tractor is a NH 1925 HST 4x4. The pump was making a squealing noise so I bought new filters and drained the hydraulic oil as shown in the owners manual. The old oil was the color of Baileys Irish Cream (7.5 gallons). I'm thinking water and dust mixed together with the oil. The new oil which I purchased from Tractor Supply is Travellers Premium (meets all NH specifications) and is as clear as water.

Prior to changing the oil, I had detached my frontend loader, a Bush Hog 2245 QT that also has a W.R.Long 4 way bucket, aka clam shell. The loader attaches via side mounts and a front bar holder. The hydraulic hoses attach to 3 nipples coming off the diverter control block.

I'd like to drain all / most of the oil that is in the loader which I suspect would hold upwards of a gallon or more of contaminated oil. I don't want to hook everything back up and introduce bad oil back into my tractor. I noticed the nipples on diverter block are shown in the owners manual as: 1) pressure out, 2) return and 3) sump tank. I'm wondering if I could possibly connect up but leave the return off and place it into a recovery bucket to catch the old oil?

I really would appreciate any helpful information on how to get the old oil out as simple and safely as possible.

Thank You!

 

[grsthegreat]

Though Ive never done this myself, i would guess that you could simply remove the coupler fittings and blow compressed air thru the system to blow out the old fluids. Blow the old fluids into a bucket.

Another way might be to hook up one side of each loop of hyd hose to the new system, remove the other end connector and slowly move the control lever to push new fluid thru the lines and displace the old fluid out the other hose into a bucket.

personally i cant think of any other way to do it.

 

[Mikey201]

Thanks grs..

The second method is what I was considering and makes the most sense to me. Only thing is there are 3 lines which leaves me scratching my head. The line out to the frontend loader I can see needs to be supplied from the tractor but the other two are: 1) return line and 2) sump tank. I don't understand enough about this configuration to know if the sump tank line needs to be hooked up or not. I would think that I could take the coupler off of the return line and pump out the old oil into a bucket. I'm just not sure what to do with the sump tank line, hook it up or drain it as well.

Any ideas?

 

[k0ua]

I can't tell you what to do, but I might be able to help some. Oh as for my credentials in the hydraulic field, well, Um.. I have none. So this is going to be worth what you paid for it. OK here goes.. The pressure line comes from the pump and is the source of the flow, so 6 to 10 gallon per minute or what ever your pump is capable of putting out. The return line comes from the loader valve, and when all of the spools are in neutral, that same 6 to 10 GPM is going to come out of this line through the loader valve.. This flow goes on back to the next valve in line, whether that is rear remotes or your 3pt valve. So if you disconnect it, as soon as the engine starts and the loader valves are in nuetral it will come from the pump thru the valve and back out here. You will be out of fluid pretty quick. Now the return to tank line returns fluid at low pressure and low flow rate back to the tank. Here is an example, lets say your lift cylinders are retracted, so there is very little fluid behind the cylinder face and of course fluid in lines. But there is fluid on the other side of the cylinder face as well as the piston rod. So when you apply fluid thru the loader valve the cylinder starts to fill, the piston starts to extend and that fluid that is on the piston rod side of the cylinder starts to come out and that is routed by your spool valves on the loader control back to the tank and will come out of that "return to tank" hose. It is low pressure because there is not much to restrict the flow and not much pressure is developed.

When you move the loader control valve the other direction to retract the piston, then the supply side flow is directed to the piston rod side of the cylinder, and the fluid from the other side is now directed back to the tank.

So I would think a cycle or 2 of the cylinders with the return to tank hose directed into a bucket would do it. Fill back up the tank with good clean fluid. I am not sure I would do this without consulting with someone who has more experience than me.:shocked: Now how you are going to do this and get the loader back on the tractor and get the curl/dump cylinders cleaned out and how you are going to raise the lift cylinders with the loader off of the tractor, I dunno. Lets see what some others with more hydraulic experience have to say.

James K0UA

 

[Harry in Ky]

What you are suggesting is probably more common than you think. I've done just that many times with loader tractors/contaminated oil. Simply remove the sump return hose from wherever it attaches to the tractor and tie it into a bucket as you described. No oil will flow with loader valves in neutral, but when the valves are operated, whatever oil comes back from the cylinders and lines will exit through this hose. Re attaching the loader is no problem, as the movement of the cylinders during attachment is just part of the flushing process, and all return/junk oil is captured in the bucket. I agree that a few cycles of all the cylinders will be needed to flush the system.

 

[Mikey201]

Thanks for the response K0ua,

I'll have to attach the loader back to the tractor to do this and I'm ok with that. I'm not sure about the flow rate; this is a compact tractor. Horse power on the engine is about 32 which drops down to about 28 due to the HST. I would have to keep the tractor at idle to keep the flow rate down. 6 - 10 gpm would drain the reservoir in under a minute as the whole system on the tractor only holds 7.5 gallons. That aside, the thing that is puzzling to me is the connection to the Sump Tank! If I already have a line flowing out to the loader and a return line then what is the purpose of the sump line and which way does it flow (to or return) to the loader?

My loader has six hydraulic cylinders: 2 (that are 1/2 retracted) that raises and lowers the frame, 2 (that are retracted) that controls the bucket position and 2 (also retracted) for the clam shell bucket. There is a button on the joy stick that when depressed controls the fluid going to the 4-1 clam shell bucket; it is electronically controlled by another diverter valve.

Information sharing to all: I had checked the Hydro oil using the dip stick, it always showed clear and full. What I failed to realize this is the top of the oil. It is wise to check the oil from the bottom drain where water and dirt accumulate. Had I done so earlier on, I would have changed the oil and filters much, much sooner thereby averting this mess!

I don't use my tractor very often and it was left parked outside so I'm sure the contrast in day / night temperatures caused condensation to build up in the tank & lines. As you probably already know, Filters and Oil are very expensive. Mine requires 2 hydro filters which retail from CAT for about $75 and CAT wants $80 per 5 gallon bucket of Multi G oil. I was able to locate the filters from O'Rielly auto parts (WIX filters) saving money there and the oil came from Tractor Supply at $40 per 5 gallon.

 

[Mikey201]

Harry - - Thanks for the reply.

So I take it from your post that you recommend that I remove both the return and sump lines couplers and drain those into a bucket leaving only the supply line hooked up?

 

[k0ua]

Remember what I described about the return line it is the flow path when the loader control is doing nothing (in Neutral) so you don't want to disconnect it. It is the flow path on to the other hydraulic control valves.. any rear remotes you may have, and the final valve is the 3pt valve. The sump (tank) return line is low pressure (nearly no pressure) is where this contaminated oil is going to come out when you start operating the loader control

James K0UA

 

[k0ua]

Harry - - Thanks for the reply.

So I take it from your post that you recommend that I remove both the return and sump lines couplers and drain those into a bucket leaving only the supply line hooked up?

No, don't unhook the return, line as the pump will just pump all of your clean fluid out of this line in a hurry. What ever the pumps flow rate is will come out of this line right now:shocked:

 

[Mikey201]

K0ua,

Ok, I think I'm following. BTW, I failed to mention I don't have any rear remotes on this tractor. I think I was confused b/c of your sentence with "sump (tank) return" which the diverter block has a return plus a separate sump tank connection as well as a outflowing supply line. Anyway, I understand now what your saying. The return line is just a loop back to the system when doing nothing.

I guess I'm just trying to be abundantly cautious and making sure I don't mess anything up.

Thanks for your help!