Hydraulic Flush!

[aighead]

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...

 

[aighead]

If a hydraulic system becomes contaminated with water or anything else, it has to be completely disassembled and ALL components drained and flushed. This means the tank, the cylinders, the valves, all hoses and tubes (all opened up, cleaned, and reassembled), and the filters and their housings of course.

This is the only way to be sure you have removed all the contaminant. Doing anything else only continues to contaminate, and wastes the new fluid you install. Just draining the tank and changing the filters only dilutes the contamination down to smaller levels every time. There will still be water left in the oil and it will do damage to your system.

Even after a complete system rebuild, the fluid and filters should be changed again after a short interval.

Fluid sampling can help determine what the water level is and you can make some decisions after knowing what that is.

Good luck!

 

[aighead]

Three weeks ago I had to do a complete hydraulic system oil change because of water contamination. This is how I did it. Retract all the hyd. cylinders even if you have block some components to keep them retracted. Now unhook ALL of the hoses from the ALL of the cylinders. Completely drain and clean out the hyd. tank and install a new filter. Fill the tank with clean oil. Now start the engine and flush all of the unhooked lines until you get clean oil coming out of them. Be sure to keep the oil tank full as you do this. Reconnect the lines on the retracted (closed) side of the cylinders. Now extend all cylinders slowly and completely. Be carefull because oil will be coming out of the extended side of the cylinders with a lot of force ! After extending the cylinders reconnect the the hoses to them. Now all the system should be completely flushed except the swing cylinders. I flushed the swing cylinders in the following manner. Stabilize and level the machine with the outriggers. With the boom on the ground so it cannot swing unhook all the hoses to the swing cylinders. Now flush all of the unhooked swing cylinder hoses. Next be sure no one is in the swing path of the boom. Raise the machine with the outriggers being carefull to keep it level until the boom is clear of the ground. I was now able to swing the boom in a full arc left to right by pushing it by hand. This will completely flush all the contaminated oil out of the swing cylinders. Next lower the machine so the boom is resting on the ground. This will prevent the boom from swinging as you reconnect the hoses. The boom has to be prevented from moving so you will not get caught as you reconnect the swing cylinder hoses. After completing this,the entire system will be flushed. This is what worked for me and I now have machine with oil in it that looks as clean as it did when the oil was new in the 5 gallon pails. It did require 40 gallons of new oil to accomplish the flush but that is a lot cheaper than replacing a hydraulic pump or who knows what else water contamination destroys.

 

[aighead]

seagull369, if you have a 580E Case, there is a way to do yours and do a fairly thorough job of it.

First, Raise the front loader all the way up, roll the bucket all the way down. Drop your outriggers. Fully raise the backhoe boom, fully extend the backhoe arm, and curl the bucket all the way in and fully swing to one side.

Then, drain the hyd reservoir and remove spin on hyd filter. Next, disconnect pipe #15 from fitting #16 on filter housing. Connect a length of hose to end of pipe #15, send that hose to a waste oil drum. Put a JIC cap on the fitting at the filter housing, screw on a new filter, this is just to prevent oil loss back through filter.

Fill the hyd reservoir. Make sure throttle is set to idle. Hold lever to roll out backhoe bucket with one hand and keep other hand on key, start engine. When bucket is rolled out fully grab lever to drop backhoe arm. When it's fully retracted, shut of engine. Add more oil to reservoir. Start engine while holding swing control to swing boom to opposite side. Stop engine and check oil. Start engine and immediately lower backhoe boom, stopping just short of contact with ground, then immediately grab levers, then grab levers to retract outriggers, stop and check oil level again. Lastly, start engine, roll loader bucktet up then drop loader. Reconnect pipe #15 to filter housing, fill reservoir to proper level.

By doing it this way you purge the bulk of the contaminated oil out of the system and send it into a waste oil drum. There will be a small amount of residual contaminated oil, but not enough to affect system.



View attachment 67664

 

[Tinkerer]

If you do it the exactly the way I described the will be absolutely no contaminated oil left in the system.

 

[aighead]

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!

 

[Delmer]

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?

 

[Tinkerer]

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.

 

[Nige]

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]

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.

 

[treemuncher]

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]

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?

 

[treemuncher]

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]

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.

 

[treemuncher]

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!

 

[Nige]

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....

 

[aighead]

Thanks guys! I'll keep this in mind and start shopping soon!

 

[aighead]

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...

 

[aighead]

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?

 

[aighead]

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.