Hydraulic system flush.

[OLD GAR]

I'm sure this has been discussed numerous times but I can't seem to find it and I am in a bind. My B7500 with a LS 272 FEL developed leaks in the tilt cylinders on the Loader. Upon disassembly found the hydraulic oil to have evidently been contaminated with water or condensation. In other words pumpkin latte color!
I've done the cylinders but want to flush out all that milkshake before recharging. Is there a procedure in any of the "free" manuals to accomplish this? Thanks. . . old gar in Louisiana.

 

[85Hokie]

The only way to flush effectively is to drain, replace and drain again, and replace.
IF you use cheap stuff to flush, you will always have a little cheap stuff behind!

It would be a neat idea if you could have a line "free" and open and continue to add new oil as the old oil is pushed out, constantly pushing from pump out. NOT sure I would try this, most pumps would squirt that oil a good way and whatever is in the way would be wet and damaged!

 

[OLD GAR]

Bought this orange beast without any manuals or documentation. It is probably a 1984 or something. I've no idea of the capacities nor where the low spots are to drain out the old fluid. Just called the local TSC and their 5 gal hydraulic oil sells for $25. Probably should buy two ? ? ?
I've had this pore little creature for a couple of years and it sits out in the weather. I've no idea how it got water / condensation in the system, but it must have just happened when post harvey dumped about 15" of rain here locally.

 

[fatjay]

Don't buy the yellow bucket. Buy the black bucket for universal tractor fluid. Yellow bucket isn't for anything after 1973.

Black bucket is $36.99. I have just done a bunch of flushes in my zero turn. Works amazing now. But there's no true "flush", there will always be a little left behind. You have to keep flushing it until it's diluted enough to not make a difference.

 

[bxray]

Maybe disonnect all the lines.
Connect an air line and push it out of the lines.
An air gun with a ruber cone tip.
Work the cylinders to try and purge them.
Long drain on trany.
And like 85hokie said fill, run and flush again.

Ray

Here is a manual.

https://www.ebay.com/sch/items/?_nk...%3D711-53200-19255-0%26rvr_id%3D1314541001146


https://www.amazon.com/Kubota-Model-B7400-Service-Manual/dp/B007HOEOO0

Watch out for the free downloads. They are usually a trap for junk.

 

[bxray]

Aftwr tou blow the lines out use a turkey baster or big syringe and inject some fresh fluid and blow it out again to help flush.

 

[100 td]

The only way to flush effectively is to drain, replace and drain again, and replace.
IF you use cheap stuff to flush, you will always have a little cheap stuff behind!

The cheap stuff left behind will be a lot better than than the crap you have in it now, so I wouldn't be concerned with doing a double or triple flush with cheap stuff before finishing with the recommended product.
Make sure you drain from all drain bungs, probably one on each axle housing plus up to 3 (depending on your machine) on transmission/HST etc.
If you can, drain all lines from FEL valve, coming to, and going away. You mentioned the tilt cylinders, what about the lift cylinders and hoses?
If the machine has been sitting you may find separated water in your axle housings when you first drain, and at the bottom of your tranny.
Don't forget new filters and to wash out the inlet/suction screens if it has them.
So how did the water get in, check your filler plug seal, and the rubber vent breathers, my breathers are loose and have probably shrunk, so when washing the machine, water can get past the breathers, I need to get some new ones. YMMV

 

[OLD GAR]

Not to "BUMP" but I found the ingress point for water contamination in the rear end. Some dummy forgot to replace the cap - rubber plug - the last time oil was put in. I usually tilt the seat up to keep rain from seeping into a couple of cracks in the seat. Of course this left the exposed port wide open to the downpours we had at that time. Fortunately I found the plug wedged down the side next some pipe.

Now this is the point where my continuing ignorance is going to show. I've crawled under this beast wiped of lots of accumulated dirt sand and other crap off and I see no drain plugs. Bolts holding the axle housings to the center section but WHERE is or are the drain or drains?
As I said before, I got no manuals or books with this B7500 and I don't get much help from anywhere but here for maintenance issues. So be kind to this old guy and point me there! }:<

 

[100 td]

Have a look at the exploded parts diagrams, I'm guessing there will be "plugs" on your axle housings and elsewhere on your transmission/gearbox etc for draining.
http://www.kubota.com/part/partsList.aspx

 

[OLD GAR]

The "exploded diagrams" didn't actually show "drain plugs" but called them "bolt with flange". Item 110. They assume that if you take out the wrong "bolt" and nothing comes out you'll figure out that you've taken out the wrong one!
Anyway there are 3 of these bolts to drain transmission through both axle housings and the pump. After I drained, flushed the lines I decided to replace all the hoses on the loader. Now I've refilled the system, done a preliminary cycle there seems to be some air trapped somewhere. It got dark on me tonight so tomorrow I'll go through the cycles again and see if I need to bleed some cylinders or if maybe the air is in the 3 point lift. I didn't find a way, if there was one, to flush the lift.

And "Thanks" members for helpful insights to this venture. Hope as time goes on I can be of help to others as you've been for me.