1. Thank you for visiting HeavyEquipmentForums.com! Our objective is to provide industry professionals a place to gather to exchange questions, answers and ideas. We welcome you to register using the "Register" icon at the top of the page. We'd appreciate any help you can offer in spreading the word of our new site. The more members that join, the bigger resource for all to enjoy. Thank you!
  2. ALL NEW MEMBERS READ THIS FIRST!! Thank you for joining Heavy Equipment Forums! If you are new to forums we communicate with "Threads", please search our threads to see if your topic may have already been answered and if not then click "Post New Thread" in the appropriate forum. This will allow all of our members to see your question and give you the best chance to be answered. After you've made a number of posts you will graduate to Full Member status where you'll see a few more privileges. Following these guidelines will help make this the best resource for heavy equipment on the net. Thanks for joining us and I hope you enjoy your stay!!

Hydraulic Flush!

Discussion in 'Lubrication' started by aighead, Apr 27, 2020.

  1. aighead

    aighead Senior Member

    Joined:
    Apr 25, 2019
    Messages:
    254
    Location:
    Dayton, OH
    Hi Gang, I did a search and didn't find any threads directly related to flushing a hydraulic system. I've asked some questions on various other threads and received some good info that I'll copy here (hopefully with the correct attributions for their authors). I also want to use this thread to ask some follow-up questions if'n y'all don't mind, as some of these comments are pretty old. I assume the theories are generally the same as when these posts were made but I'd like to get updates if they are needed as well. I really appreciate the assistance you guys provide, it's extremely valuable for folks, like me, that don't have a clue.

    All that being said I'm aiming to flush my hydraulic system for the first time, next week, if I can. I'm nervous about it due to the expense and the work, but after I read through a reply by @Tinkerer, that I'll post below, several times I feel a little better about it.

    Please let me know if you have any suggestions that I may be missing! I'm also hoping this sort of post is allowed as I'm attempting to consolidate advice on this topic...
     
  2. aighead

    aighead Senior Member

    Joined:
    Apr 25, 2019
    Messages:
    254
    Location:
    Dayton, OH
     
  3. aighead

    aighead Senior Member

    Joined:
    Apr 25, 2019
    Messages:
    254
    Location:
    Dayton, OH
     
  4. aighead

    aighead Senior Member

    Joined:
    Apr 25, 2019
    Messages:
    254
    Location:
    Dayton, OH
     
  5. Tinkerer

    Tinkerer Senior Member

    Joined:
    May 21, 2009
    Messages:
    4,704
    Location:
    On A Riverbank in IL. USA
    If you do it the exactly the way I described the will be absolutely no contaminated oil left in the system.
     
    aighead likes this.
  6. aighead

    aighead Senior Member

    Joined:
    Apr 25, 2019
    Messages:
    254
    Location:
    Dayton, OH
    Thanks @Tinkerer I've got your notes printed out and ready. One of my main goals of this thread was to ask you some questions about the way you did it...

    I've read your notes about 10 times and here is what my puny brain is gathering, feel free to tell me I'm wrong and dumb... I'm aiming to get at any accessible hose that I can, specifically the hoses connected to cylinders that hold most of the fluid (other than the tank), and disconnect them to remove as much of that fluid as possible. Then, upon startup, with un-retracted side disconnected, blow out any fluid that are in the lines heading to the cylinders, until they are full of good fluid, whereby I reattach them and viola clean?

    1. Clean the hydraulic tank? Do you have a suggestion for doing so? Like really try to get in there to clean it? Jam a shop-vac hose in it?
    2. As far as hoses are concerned, I'll need to look at my machine to make sure I understand. If I'm recalling properly there is a manifold, or several, that have hoses that go from the hyd. pump out to a mid-way connection near the cylinders? Do I disconnect from that mid-way connection then the cylinders? So I'm blowing out any bad oil left in between the manifold and the mid-way connection? (There is probably a better way to say it than mid-way connection.)
    3. Keep in mind that I'm not the EPA... Did you have a good method for catching all the oil that was coming out of the hoses and cylinders? I have a couple 55 gallon drums sitting around but I don't think, unless I hook up another hose to these fittings, that I'll be able to catch most of this fluid. I'm assuming I should picture an elephant blowing water out its trunk all over?
    4. My tank, I think, holds like 34 gallons of hyd. fluid. Should I expect your same range of 40 gallons? I don't know to expect fire hose or trickle upon flushing this stuff out.
    Thanks as always for your expertise!
     
  7. Delmer

    Delmer Senior Member

    Joined:
    Jan 4, 2013
    Messages:
    6,001
    Location:
    WI
    4. If your tank holds 34 gallons (drain and refill capacity), then I'd assume another 10-15 gallons in the system, plus a little extra wasted in flushing, so probably 50 gallons or so.

    3. As long as there's no air, the fluid will shoot out, but not blast all over. A hose stuck in a barrel with some wire to hold it in place should catch it all.

    2. The hoses to the cylinders will all come from the control valves. Mostly disconnect the oil lines at the cylinders as that's the end of the line, no need to do anything in the middle of the line.

    1. depends on the tank, if it has a good drain, I might flush it with diesel fuel a few times, letting the fuel settle and reusing it until the tank is clean, then suck the rest out with "the suck bucket".

    A#1 question: what is the purpose for this flushing? major failure? water contamination? most backhoes never get a flushing this good, and most probably don't need it. change the filter, send in an oil sample and then think about flushing it next time?
     
    aighead likes this.
  8. Tinkerer

    Tinkerer Senior Member

    Joined:
    May 21, 2009
    Messages:
    4,704
    Location:
    On A Riverbank in IL. USA
    It is critical that you constantly keep the hydraulic tank full when purging the lines.
    The FEL hoist and bucket cylinders need to be done at the same time. Because they are fed and emptied by the same lines. Be sure all cylinders are dead ended and empty before reattaching the lines that now have clean oil in them.
    You will need to block up the loader and backhoe so that you can fully extend and retract the cylinders.
    BE VERY CAREFUL WHEN YOU TAKE THE SWING CYLINDER(s) HOSES OFF !!
    DEATH OR INJURY CAN OCCUR WHEN THE BOOM IS ABLE TO SWING FREELY !!
    And it must because they can be emptied by swinging the boom by hand completely from one side to the other.
    Don't worry about any manifold. Like Delmer said, the oil that comes out of the control valves will be clean when you run enough fresh oil thru the pump.
    The parts book shows a simple drain plug on the bottom of the hyd.tank.
    I catch as much waste oil as I can. I do the flushing out in the dirt anywhere. No floor cleaning for me. A good fire over the mess will clean it up.
     
    aighead likes this.
  9. Nige

    Nige Senior Member

    Joined:
    Jun 22, 2011
    Messages:
    14,583
    Location:
    G..G..G..Granville...........!!
    When filling the hydraulic tank on a new or repaired machine I usually ignore the sight glass and fill the tank right up to the neck, then have a 5-gallon jug of oil at hand for the first startup when the oil disappears from the tank apparently faster than you can blink.
     
    aighead likes this.
  10. aighead

    aighead Senior Member

    Joined:
    Apr 25, 2019
    Messages:
    254
    Location:
    Dayton, OH
    Thanks Guys!

    Delmer- the reason for the flush is I have a fair amount of water in the mix. It wasn't noticed until I went to change a broken hose and everything looked like a milkshake. I've also noticed a decrease in force, and I'm assuming a good flush and filter change will help, if not I'll have to look deeper. I'll also keep an eye out for where the water may be coming in, hopefully nowhere!

    Tinkerer- Duly noted. I did reread that part of your initial notes several times over as well and I understand the damage I could cause, thank you!

    Nige- sounds like a good plan. I expect I'll over buy. I'm sure to have a bucket or two left over when it's all said and done.
     
  11. treemuncher

    treemuncher Well-Known Member

    Joined:
    Dec 31, 2006
    Messages:
    154
    Occupation:
    eatin' trees, poopin' chips
    Location:
    West TN
    I've trashed a few pumps/motors over the past few years. In order to clean my systems with a good flush, I use a filtration cart to pump fluid through the lines to attempt to dislodge any particulate matter. As per a hydraulic shop's advice, I use diesel fuel as my main flushing media. This will become mixed with oil and filtered while flushing so it gets saved as a secondary flushing media for future use. I start with diesel, then mixed diesel/oil and then to clean oil. I have a large selection of fittings just for this purpose in order to re-loop my lines as required with the cart. Normally, I will try to flush each loop in both directions.

    If you have water contamination in your system, you could also install a bypass filter with water absorbing media. I think that this is the only other option, other than total disassembly and cleaning, to really get all of the moisture out of a system. It's good maintenance anyhow. You could also use a filtration cart to do this but it won't be working all of the time like a bypass will.

    I normally drain, filter for 30-60 minutes and then re-install my hydraulic fluid every 6 months or so on my most used machines as a good PM measure. I have extra fittings on my tank just for this task. Hydraulic fluid will never go bad if it is not overheated but it will get contaminated if not filtered properly. I normally use 2 micron final filters in my cart to ensure cleanliness. When I transfer new fluid out of a barrel, even that really needs to be filtered. Filters are a lot cheaper than the parts and labor of a hydraulic system.

    Water does not show in hydraulic oil until in meets the saturation or holding point. Only then does it become milky and then it is too late. If any of my machines ever got this bad, I would install a bypass filter immediately after flushing the system and replacing the oil.

    Did you find the original point of contamination and resolve that issue?
     
    aighead likes this.
  12. aighead

    aighead Senior Member

    Joined:
    Apr 25, 2019
    Messages:
    254
    Location:
    Dayton, OH
    Thanks for the tips treemuncher! I have not found the the issue allowing water in, I'm not sure where to even begin looking, but it may have come from the place I bought it that way.

    Is the cart you speak of something you can buy somewhere? Expensive?
     
  13. treemuncher

    treemuncher Well-Known Member

    Joined:
    Dec 31, 2006
    Messages:
    154
    Occupation:
    eatin' trees, poopin' chips
    Location:
    West TN
    There are numerous manufacturers of these filtration carts. Mine is a Parker that I purchased used off of Ebay many years ago. I think I paid around $900 at the time and new was then $1500-$2k. I chose Parker above others because there is a reasonable selection of filters available and I can purchase them at Napa easy enough. Coarse filters are usually 40 micron and final filters are 2-20 micron depending on what you use. Water removing micro-glass filters usually only go down to 10 microns. Replacement filters are $40-$100 each but you might find them cheaper. There might even be cross overs to Donaldson or Baldwin by now.

    You can build a filter cart easy enough with a hydraulic pump and filters. Napa sells filter bases for spin on type. At the least, I would consider a bypass filter on your system until that oil stays really clear. All you need to do is tap off a main pressure line with a flow control and run that through the filter and back to tank. Preferably, with a pressure control valve that limits you to about 30 psi and very slow flow rate with an adjustable flow control or an inline orifice valve could do all of that if you need to keep it cheap. A pressure gauge would also be wise to make sure you don't over-pressure that filter and know when to change it out.

    I've run bypass filtration on many of my engines and hydraulic systems for years. Filtration Solutions made the canisters that I currently use. I think that they go to 2 microns. They also have/had a lot of information regarding the importance of clear oil in mechanical devices.
     
    aighead likes this.
  14. aighead

    aighead Senior Member

    Joined:
    Apr 25, 2019
    Messages:
    254
    Location:
    Dayton, OH
    As I understand it there are 50 million fluids for everything. I'm not knowledgeable to get into the intricacies of various fluid components and spec sheets, etc.

    So, I'm looking for a general purpose hydraulic oil that would work well in my backhoe. I don't need the best of the bunch, but I'd prefer to not ruin my machine as well. My machine likely only gets a couple hundred hours a year, if that.

    That being said does anyone have suggestions for a decent quality hydraulic oil? I saw this on Amazon, but other than 6 reviews saying it's good I don't know if it really is or not. Really, I have no idea what is an acceptable, decent brand and when I go looking for info here it's hard to decipher the massive amount of info for a "good enough" oil.
     
  15. treemuncher

    treemuncher Well-Known Member

    Joined:
    Dec 31, 2006
    Messages:
    154
    Occupation:
    eatin' trees, poopin' chips
    Location:
    West TN
    I've been using Sinopec in most of my hydraulic systems for the past few years and I've not had any issues. First, I tried their 46 & 68 hydraulic oils and later, I tried the semi synthetic motor oil. I've not had any problems at all. I do know their hydraulic oil is very slick and tough to get off of my hands. Why should I pay Mobil nearly $900 for a barrel of hydraulic oil when I can get a suitable product for under $350, delivered?

    I did a lot of research before trying this brand of oil. My cousin is a retired petroleum engineer - he assured me that if it passed the tests and makes certifications, the oil is as good as any other that passed those tests. Certification is not a given for any product. According to the manufacturer, this particular brand is refined through the Shell oil company refinery, the same piping and distillation towers as Shell branded products. Many others may want name brand stuff but I'm happy with what I've been using for the past 4+ years.

    When I blow a line, like I did last week, and lose 40 - 80 gallons in a matter of seconds or minutes, cheaper oil does not hurt my wallet as much as the name brand stuff would have.

    Now, if my Menzi Muck blows a big line, you will hear my wallet crying 5 counties over - Panolin synthetic biodegradable hydraulic oil is roughly $300 per 5 gallon pail!
     
  16. Nige

    Nige Senior Member

    Joined:
    Jun 22, 2011
    Messages:
    14,583
    Location:
    G..G..G..Granville...........!!
    Stick with a branded oil. You should be OK if you stay well away from parts house offerings, anything with "tractor" in the name (appeals to farmers and we all know how cheap they are), and Joe Blow's Gas & Groceries specials....
     
  17. aighead

    aighead Senior Member

    Joined:
    Apr 25, 2019
    Messages:
    254
    Location:
    Dayton, OH
    Thanks guys! I'll keep this in mind and start shopping soon!
     
  18. aighead

    aighead Senior Member

    Joined:
    Apr 25, 2019
    Messages:
    254
    Location:
    Dayton, OH
    I'm looking at my service manual and it appears as though my front and rear axle should be lubed with the same hydraulic oil as my hydraulic system? Is that right? I don't know why by I expected something thicker...
     
  19. aighead

    aighead Senior Member

    Joined:
    Apr 25, 2019
    Messages:
    254
    Location:
    Dayton, OH
    OK, so I feel bad for whomever may end up delivering this, if I go with it, but I'm assuming I can use this stuff (Sinopec AW 46 Hydraulic Oil Fluid (ISO VG 46, SAE 15)) from Wallyworld?

    My manual says the below, but I'm making some assumptions on which of these specs or numbers makes a difference. Should I be looking primarily at the ISO 46 or does the other stuff mean some particular things I need to worry about too?

    BHfl.jpg
     
  20. aighead

    aighead Senior Member

    Joined:
    Apr 25, 2019
    Messages:
    254
    Location:
    Dayton, OH
    Welp, thanks to a very knowledgeable neighbor we got it done. Unfortunately it's not as water free as I'd like but it's much closer and maybe another flush this time next year when I'm better prepared I'll get completely rid of it. All things considered not as miserable as expected though we did work for about 12 hours, replacing batteries (the hard part, thanks rust) changing fuel, hydraulic, oil filters (hydraulic was really on there, had to run a screwdriver through and use a cheater bar) and putting new oil and hydraulic oil in. Phew.
     
    Delmer likes this.