Hydraulics questions again :)

[Wa11banger]

Hello fellow TBN peoples.. I am back with hydraulic questions again.. I know crazy right? I will be starting a build (maybe rebuild ) thread here shortly for a new toy I just bought but I need some hydraulic assistance to get there first.

I just bought a Dig-It tow-able backhoe! I know, I know, there will be haters but lets not get into why or why not to own one. I am fairly excited that I get to work on a new toy and could care less if another thing can do it faster or better than the thing I just bought. Please stick to the topic at hand and that is the hydraulic questions I am at a loss for.. I did some searching on TBN and I don't know if I didn't use the proper key words but I couldn't find an answer for total empty system or how to properly get wrong fluid out of one completely so here goes.. I hope I am not repeating.

I bought the Dig-it from someone that really didn't know anymore than I did about hydraulics and apparently cant read warning labels either and he filled the hydraulics up with universal hydro fluid. There is a 4 inch sticker right next to the filler that says fill with 10w-40 motor oil..

Can anyone guide me to the proper way to bleed the whole system? it was run quite a bit like this but I do not believe it is working to full potential.

Step 1
Drain huge reservoir.. Check! got that far

Step 2??
how in the world do I get it out of the great number of valve bodies and the the cylinders? That is where I am lost. I thought about going circuit to circuit and loosening the retracting return line then tightening and working on the extending return line etc etc.. But I wanted to make sure I was not making more work for myself than necessary. Also thought about using air pressure to blow all lines clean first and see if I could get the pump to refill all of them but wasn't sure having a completely dry system was something I needed special tools or pressurized system to make work again.

Any and all help is greatly appreciated and I look forward to the responses..


JJ, Greg, and Rich I know your out there

 

[J_J]

You could use most any mineral based hyd fluid for your climate and it should work.

Even ATF would work.

Power-Trac owners have been using engine motor oil in our machines for about 20 years and works very well.

As far as bleeding, just cycle all the cyl about 10 times, and the air should purge itself.

Put a hyd gage in the hyd system and tell us the relief pressure.

Are you using a 10 micron return filter?

 

[Wa11banger]

Thanks for the reply JJ.. Just so I don't go messing it up.. You said as far as bleeding just cycle about 10 times and the air should purge itself.. Is that answer in reference to my completely opening the system and blowing all lines clear or just if I break open any singular spot.

it has a pressure gage on the filter housing.. I have to replace the lens as the dial is barely visible through the lens. But will report out once I get it back up and running again.

 

[J_J]

Any time you open any part of the hyd system, air might enter the hyd system, and the hyd system needs to be purged.

Symptoms of air might include mushy operations, erratic operation, slow, jerky, no function, etc.

 

[Wa11banger]

But if I open it up completely, perform a full purge of all lines will it recover from that? Starting from just air in lines and cylinders and fresh fluid in the reservoir? Or is there a priming procedure to do first. Sorry for the hydraulic ignorance but even google has been no help in my research. Again, I appreciate the advice

 

[muddstopper]

I dont know how much oil the machine holds, sounds like a small piece of equipment. To change fluids in the past, I have drained the tank of all fluid. Fill tank with new fluid. Then remove the return line from the tank and place hose end into and empty container. Crank machine at idle and watch the oil for a color change as it is being pumped into your empty container. As soon as the oil changes color, shut off machine and reconnect your return line hose. Now change your filters and your done. Oil is changed and only takes a few minutes to do it. I have done this on machines that hold 2-300 gal of hydraulic fluid and on machines that only hold 5 or 10 gal of fluid. Once I did a oil change over from Rando68 to dextron3 on a whole fleet of equipment. About 50 machines. It took 3 men all day to get the job done, but our bosses where surprised we where able to get it done that fast. Of course we had a engine driven pump to suck the tanks dry and refill with new oil, and a tanker truck to pump the old oil into.

 

[Fallon]

Just fill up the tank & run it, the pump will push fresh oil into lines & push out the air. Run the cylinders in and out a dozen times & the oil will end up purging out the air in the work lines & cylinders.

 

[Wa11banger]

Thanks for the info all.. its a smaller machine for sure but not as small as most think its as big as a compact car.. It's bigger than my kids dodge neon was.

Muddstopper, If I had to guestimate I'd say the reservoir holds between 12 and 15 gallons and as new as I am to this stuff I couldn't begin to guess what the rest of the system holds. I am familiar with the purge process you described but I assumed that only worked on single sided hydraulics. Maybe I misunderstand how it works. My thought on it was that once full, the hydraulic fluid only went back and forth in the system. I didn't think it was a recirculatory system where fluid in the cylinder would make it back to the reservoir.

Fallon, thanks for the input, I wasnt sure that if the system was completely dry that it would be able to refill the lines and cylinders without special support equipment

 

[aczlan]

I would just use it with the UTF in it and change over to 10W40 next time you change the oil...

Aaron Z

 

[davedj1]

I would just use it with the UTF in it and change over to 10W40 next time you change the oil...

Aaron Z

I would do this also, just run it as is.

 

[muddstopper]

True, just purging the system with new oil wont get the oil out of the aux hoses that run to the cyl, or from the cylinders themselfs, but just run them in and out while doing the purge and that would take care of it. We didnt operate any of the equipment when we where doing the change over from 68 to dextron. That has been several years ago and most of that equipment is still in service today. I dont think you have anything to worry about mixing what ever residual oil would be left over after the purging with new oil. In fact, I would just probably run the machine as is and wouldnt bother with trying to switch back to 10w40.

 

[sparc]

I have a Dig-It. It has 10-40 oil in the hydraulic system.
I've never had a leak or need to top off in the 2 years I've owned it
so not much help. Some parts are still available. I have a contact number
somewhere I will dig up and list in this thread.

 

[Wa11banger]

I have a Dig-It. It has 10-40 oil in the hydraulic system.
I've never had a leak or need to top off in the 2 years I've owned it
so not much help. Some parts are still available. I have a contact number
somewhere I will dig up and list in this thread.

Thanks sparc I appreciate it.. I am at the point where I need to find parts if available.

Since my last post I managed to get me one deer in the freezer so I can focus a little more on the Dig-It. so here is what has happened so far.

I removed the curl cylinder and sent it off to be rebuilt. A local guy says he can do it for $60 so I am going to take him up on it. Unfortunately, the fluid that came out of it was more like chocolate milk and not any fluid I have ever seen so a complete drain of the system will be on the to do list before reassembly. I figure I will drain the reservoir, and fill with fresh clean fluid. then remove the return line and cap it off putting the return in a bucket. Then purge each circuit until fresh clean fluid runs from the each of the cylinder supplies. after cylinder is stroked both ways. Best way I can think of without making a total mess out of the shop.

as I was removing the cylinder I noticed a lot of play in the pins and bushings on the bucket, bucket links, and the dipper arm. So I pulled them all and the bushings are worn pretty good and one of the pins is rusted and shot. So I will be trying to find compatible replacements before reassembly.

With that being said if I cannot find them I have done some research on the threads for how to make bushings and that is completely confusing depending on who wrote what I still do not know what the good candidate metal is for homemade bushings. I hate to start a new thread on this with all the ones currently covering it but a layman as myself cannot make sense of the differing options in each thread. So if one of you have some experience in this area please let me know what your recommendation is. I have have knocked the bushes out of the bucket, bucket links, and dipper arm. They are not weld in but a press fit. They have 1.5" OD and are .5" wide but unfortunately ID shot.. One of the better pins has an OD just shy of 1.25" so I would assume the ID of the bushings should be around 1.25"