Hydraulic oil, changing and flushing system ?

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le.maisonniau
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Hydraulic oil, changing and flushing system ?

Post #1 by le.maisonniau » Tue Oct 31, 2017 10:47 pm

Hi Guys,

I am now at the stage in my restoration of my Hitachi EX27u where I am tackling the hydraulic pipes and oil.

The oil has never ever been changed on this m/c, the service interval is 3000 hours and it has 3220, so I guess the previous owner wasn't too bothered. :thumbdown:

However, the oil never having been changed nor inspected nor water drained off, is in a shocking state :x , this I guessed when I bought the m/c so am not greatly bothered as I intended to drain the system down, replace all filters and put in new oil.

So, having removed a couple of pipes I deemed could do with replacement, I drained some of the existing oil into a jar to see what it was like - see pix. This sample came from one side of the boom, pipes that feed the pecker! About 2meter of pipe !!.

My question are: Given that I need to drain all of the oil/water completely from the system, and draining won't be a problem, what I am concerned about is making sure that when I refill the tank and start the pump I am A: not going to cause damage with a possible dry pump !! B: that I am going to get all of the water (emulsion) out of the system and C: also I do not want to create air blockages. :dizzy:

Could someone suggest a table of events or a logical order for me to follow, or any hints or tips. Time is not a problem, so can fill the tank and let it rest for however long is necessary etc. Slacken off far end of a run to bleed air etc, just need a point in the right direction :thumbup:

Cheers
John
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Re: Hydraulic oil, changing and flushing system ?

Post #2 by essexpete » Wed Nov 01, 2017 12:21 am

Crikey that is going to take some flushing through. I have a feeling that variable displacement piston pumps may be more prone to cavitation damage than a gear pump (especially if the housing is a robust casting). You really could do with some advice from someone who knows their way around your machine. You must be careful with hydraulic oil under pressure (you probably know that anyway).
You might have a job to clean out all the old oil. My take would be to drain the tank and any pipes that can be easily disconnected, oil cooler if fitted. Reconnect the pipes, change filter, refill and perhaps loosen the pipe feeding the pump to make sure oil is there. I guess you will have some contamination within the rams. That might be more tricky to eliminate, on the other hand unless there is a major piston seal failure the oil will not really feed back to the tank. You might get some oil out of the rams by pipe removal. Opening and closing all the services should work air out of the system. On first start up you could turn over the engine without running a little and then just idle initially.


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Re: Hydraulic oil, changing and flushing system ?

Post #3 by diggerjones » Wed Nov 01, 2017 12:37 am

What's the oil like in the tank. It might just be crap oil in the pipe. If it's not had a breaker on or any other attachments, the oil may have been in there years


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Re: Hydraulic oil, changing and flushing system ?

Post #4 by Jeremy Rowland » Wed Nov 01, 2017 8:47 am

I think that I would be tempted to drop the old oil out and sacrifice some fresh oil; fill the machine with fresh oil, to the bare minimum and run that round the machine so operate all of the controls to do that, one you have used the machine a couple of times drop the oil back out and fill again with new oil, then change the hydraulic oil filters as well.
To be fair I don't know if you bleed anything on these machines on my 580BT there is a bleed valve located underneath the small hydraulic pickup tank to the pumps that you are supposed to bleed whenever you use the machine as it's not a fully pressurized system like the later 580C, that being said I cannot see 1970's digger operators bothering to do that all the time.
As for your 'milky' oil; years ago when I was a kid and I used to operate the Hymac's at Chas Penn's scrap yard I can recall one of the sons topping up the hydraulic oil in the main tank on the 880 and he took the top off the tank to do this, the oil looked exactly like that, like a creamy milky substance, needless to say that oil did not get changed and the machine was simply operated for years like that.
Okay so scrap yard machines get fully abused all I am trying to say is don't panic with your machine I can't really see any damage being done; with the Hymac 580BT that I am currently restoring the hydraulic oil level was dangerously low as the machine had a bad leak plus the pumps were already well and truly knackered, once the pumps had been repaired I simply topped up the system with new oil about 30 gallons of it so I knew there was little residue in the system plus the former owner had topped up the oil so in a roundabout way the oil has been fully changed, plus the filters. To be fair I was expecting the oil in my machine to be milky but it was fairly clean hence me not dropping what was left of the old oil out.

Jeremy


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Re: Hydraulic oil, changing and flushing system ?

Post #5 by essexpete » Wed Nov 01, 2017 9:39 am

That milky appearance is water contamination. Personnally I think it would be best to get rid of a much as possible. I know where Jeremy is coming from, when I was a kid all of our collection of knackered machine only got a top up. The old MF 203 220 digger did nearly stop working but replacing the big suction filter cured that. That was mostly water contamination sledge.


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Re: Hydraulic oil, changing and flushing system ?

Post #6 by le.maisonniau » Wed Nov 01, 2017 10:06 am

Hi Guys,
Thanks for the replies, I intend to drain ALL of the oil out and discard, so I think Jeremy's note on filling to bare minium, running for a while and dropping it all out again is a good one.
The oil in the tank - i.e viewed at the perspex level indicator is exactly the same milky stuff as in my little sample jar :shock: , so I guess there is a large amount of water in the system. I don't think (hope there isn't) there is any damage on the pumps as they "sound" quite sweet :claphands: , but I am taking this oportunity to thoroughly clean the system. As Jeremy suggested, if I sacrifice some oil to start with, this should flush the system through. :thumbup:
There will be a need for bleeding, I spotted a note in the handbook, but not read that far yet as I'm not ready, but will soon.
I am off to UK tomorrow and will be picking up new bearings for the tracks and a complete set of filters, I will get an extra prefilter, run the flushing through that, clean the old filter best I can, and then put new filters in after flushing - does this sound like a plan :lol:

I will catch up on progress in a fews weeks when I am back in France.
Cheers
When you come to a fork in the road - take it :dizzy:


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Re: Hydraulic oil, changing and flushing system ?

Post #7 by corksil » Thu Nov 09, 2017 6:47 pm

I'm pretty sure I've got the manuals for that machine


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Re: Hydraulic oil, changing and flushing system ?

Post #8 by le.maisonniau » Mon Jan 01, 2018 2:45 pm

Update.
Last week I drained the tank and have been worrying about restarting the engine after refilling the tank in case I have air in the pump and create cavitation problems; So after lots of browsing on my pump (Uchida AP2D12 LV3RS7) and not being able to find an exact match to my pump layout, I decided to slacken off the pipes on the pump - fortunately they have what appear to be bleed valves !!! - milky oil came out of these, so could presume NO AIR. Filled the tank to Full and just over the top level, ran the engine on lowest revs for a couple of minutes and then let it settle, needed to add another 2 litre of oil to bring it to lowest level, I have now let it rest for 24 hours to let any air in the system to rise up!!!. The perspex level shows a "slight" discolouration, but no where near as bad as it was.

My plan is to finish off the track work, get it back on the ground, give it a little work over and check the oil again, then after a couple of months working, refresh oil and filters this time checking the pipes at end of run and drain if required.

I have a question of oil flow, but will post seperately :thumbup:

Some pictures of interest:
Pump:
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Draining the tank:
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Tank suction filter:
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Pump pre-filter
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Fresh 'clean' oil : Note air bubbles, they disapated over night :-)
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In the mean time - a bit of pipework to keep me busy.
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Pipes from HES in Gloucester.
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Re: Hydraulic oil, changing and flushing system ?

Post #9 by FOWLER MAN » Mon Jan 01, 2018 6:12 pm

Hi John,
Sorry I'm so late picking up on this thread. You have received a lot of good advice and done everything right.
I have worked on most hydraulic diggers ever since they first appeared in the 1960s. Flushing a contaminated system has always been a problem.
The manufacturers advice, (Hymac, Priestman, Poclain etc.), was simply to close all the rams as far as possible to minimise the amount of contaminated oil left in them, drain the tank which will at the same time normally drain any oil cooler fitted.
Change the return line filter and change or wash out the suction strainer / filter. Carefully clean out the bottom of the hydraulic tank finishing with a lint free cloth and replenish the oil to the top level before starting.
This was always part of the 12 monthly or 2,000 hour end of warrantee service when I did a bit of work for Priestman.
The new oil will gravitate to the pump and whilst it cant be bad to release air through the pump feed union, (or bleeder if fitted). It only takes seconds for the system to recharge so the pump Will not suffer any damage. Any cavitation will clear as all the services are quietly and carefully operated.
This was the procedure for gear and variable displacement piston pumps.
It was never considered practical to drain the lines or rams any further.

Fred


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Re: Hydraulic oil, changing and flushing system ?

Post #10 by le.maisonniau » Mon Jan 01, 2018 10:30 pm

:thumbup: Fred, thanks for that confidence boost, I feel a lot happier now.
I will monitor the lines and rams over then next few months.
Cheers
When you come to a fork in the road - take it :dizzy:


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