Fluid in hydraulic cylinder is milky but in rest of tractor, fluid is clear.

[jgoodma1]

I have a Kubota L48 TLB. The dipper stick cylinder on the backhoe began to leak pretty badly about a month ago and today I removed it to take it to the dealer for a rebuild. I disconnected the 2 hydraulic hoses from the cylinder, knocked out the 2 pins attaching the cylinder to the backhoe dipper stick and removed the cylinder. I laid it horizontally and drained the fluid that was in the cylinder into a bucket. In the two attached photos, the first one is new fluid directly from a 2.5 gallon jug of Kubota hydraulic fluid, and the second photo is the fluid that came out of the cylinder that I'm having rebuilt. Based on other posts I've read, the milky fluid that was in the cylinder means that water was contaminating the fluid. But, I have been checking my fluid every time I use the machine (and I have been using it more than usual over the last month) and whenever I check the fluid, including today, it looks clear. Also, I had complete fluid change done at the dealer, 90 hours ago.

Today, I didn't have a good way to pull some fluid directly out of the hydraulic fluid reservoir. I could only pull out the dipstick and look at the fluid, but I did that several times, one right after the other and was able to get enough hydraulic fluid on my finger so it would drip. That fluid was definitely clear. I then took the dipstick and dipped it in the bucket with the drained, milky fluid and used the dipstick to put the same amount of fluid on my finger, as before, and that fluid definitely looked milky as it dripped down my finger. Now.....the machine is stored outside with a cover over the driver's compartment. When stored, the dipper stick cylinder faces up, so I'm thinking that with the bad seal that was leaking.....could rain be entering the cylinder at the piston seal? We have had some heavy rain over the past month. Also, I have used the backhoe for only about 10 minutes over the past month, and that was 1 week ago. Otherwise, that cylinder has been inactive. And, the day before I used the backhoe for that 10 minutes, I pressure washed the machine, and definitely squirted 2000 psi water around the piston ends of the hydraulic cylinders.

QUESTIONS:
1. Is it a mistake to use a pressure washer around the seals of the hydraulic cylinders?
2. Is it possible for the hydraulic fluid in the cylinder to be contaminated, but not the rest of the fluid in the machine?
3. With what I've described in this post, do I need to suck it up and perform a complete filters and fluid change?

Thanks!

 

[Peter 315]

1. If your close you could force water in/or ruin the wiper seal... If it was allready leaking if oil can get out water can get in....
2.yes if you pressure washed it and did not use the backhoe the oil would just stay in the cylinders and not move to the pump etc....
3. Maybe drain some hyd oil out from the system after the tractor sit over nite and see what it looks like.....

 

[jgoodma1]

Thanks.....won’t make the pressure washer mistake again. I’m an idiot

 

[fried1765]

Thanks.....won稚 make the pressure washer mistake again. I知 an idiot

When you get the repaired cylinder back on, and the reservoir topped off, just use the hoe for several hours.
Then, use an automotive brake fluid tester ($10 @ Amazon, or auto parts store) to determine the % of water in your hyd. fluid.
You may need to do a complete fluid change, but a test reading will give you that answer.

 

[5030]

I answered you on the other forum you posted the question on....

 

[jgoodma1]

When you get the repaired cylinder back on, and the reservoir topped off, just use the hoe for several hours.
Then, use an automotive brake fluid tester ($10 @ Amazon, or auto parts store) to determine the % of water in your hyd. fluid.
You may need to do a complete fluid change, but a test reading will give you that answer.

Thank you. At what % would I need to change the fluid....do you know?

 

[jgoodma1]

Thanks.

 

[fried1765]

Thanks.

My tester (Amazon) has an indicator range, with suggestions.
I think it shows 1% is OK, 2% recommended change, and 3%=DO IT!

 

[Peter 315]

Any water in the system will cause rust and problems later on you can add this stuff also if you have water before you change it......How to use Trans Tune in hydraulic fluid | Sea Foam Sales Company

 

[jgoodma1]

Any water in the system will cause rust and problems later on you can add this stuff also if you have water before you change it......How to use Trans Tune in hydraulic fluid | Sea Foam Sales Company

Thank you. I have another question that I've been trying to get feedback on: I'm definitely going to change the fluid. I asked on another forum....how do I purge all the contaminated fluid from the cylinders when I drain all the fluid from the machine. One answer I got was that I need to disconnect all the hoses from all the cylinders, disconnect the rod ends of the cylinders from the pins and manually pump the rods to purge all the fluid from the cylinders. Then I need to disconnect the hoses from the valve blocks and drain them and the valves.

Yikes! that's a lot of work. I'm more than willing to spend a few extra bucks, so what about this idea:

1. Before I drain the machine, I retract all the cylinders as far as possible, and 1 of the 2 boom swing cylinders.
2. I remove the pin on the one extended boom swing cylinder and manually retract that rod.
3. Now, I remove the drain plug/plugs and drain the system and change the transmission and 2 hydraulic system filters.
4. I refill the system with new Kubota UDT fluid and install new filters. I operate the machine for a couple of hours
5. Now I repeat step 1 and then drain the system again.
6. I refill the system with new Kubota Super UDT2 fluid and install new filters.

If that would not be enough purging, I could perform steps 1-4 twice before moving to step 6. Would that sufficiently clean the system so I could not have do go through all the cylinder and valve and hose disconnects?