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what solvent is best for flushing hydraulic system

TorontoBuilder

Ultra Member
As the title implies, I want to flush a hydraulic system of our surface grinder. I dont know if if is a good idea or not but at the very least I want to pump out the hydraulic fluid reservoir at the bottom of the casting, and pump a solvent repeatedly thru a filter to clean any crud out of the base. There is no other way I can see to clean out the base tank.

I'd like to flush the hydraulic lines that lubricate the ways and then have the solvent flow back to the tank using the ground pathways to clean them out too... and if it wont hurt anything the hydraulic cylinders too

What is best for this... and what wont explode and burn me to a crisp
 

Dabbler

(John)
None. Use hydraulic oil unless there is a LOT of crud. Then it is 20 wt oil and hose scrubbers. Depending the on the number and type of seals, it can get complicated. One guy 'refurbished' my downfeed on my bandsaw (before I bought it). 2 months in, all the seals had dissolved. Some kind of solvent he used softened everything up, and catalytic reaction from there. when I got to it 6 months later all that was left was sticky goo where the seals were.

If the sump and filters are not too bad change the filters and wipe out the sump and change the oil. After a few hours of operation, check the filters.
 

Bandit

Active Member
The best I know of is hydraulic oil it self, could maybe try diesel fuel, would be cheaper then hydraulic oil. Not sure if would work O.K. Don't try to clean filter unless it is only a screen, don't want pieces of filter in system to clean out also. Price of filter/price of machine/pump. Change filter a few times after getting running. Not sure how much oil you are talking about. A filtering system can be set up with own filter and pump/motor to circulate oil to clean if over 20 gal. or more. Again price of oil/price of machine.
New oil, new filters, happy machine, happy happy LOL operator.
 

TorontoBuilder

Ultra Member
None. Use hydraulic oil unless there is a LOT of crud. Then it is 20 wt oil and hose scrubbers. Depending the on the number and type of seals, it can get complicated. One guy 'refurbished' my downfeed on my bandsaw (before I bought it). 2 months in, all the seals had dissolved. Some kind of solvent he used softened everything up, and catalytic reaction from there. when I got to it 6 months later all that was left was sticky goo where the seals were.

If the sump and filters are not too bad change the filters and wipe out the sump and change the oil. After a few hours of operation, check the filters.
yeah I know about issues with seals and that is why I asked.

I'll pump out the tank, pull the filter and clean it, and then flush repeatedly with an ISO 22 hydraulic fluid,
 

Bandit

Active Member
I have used a vacuum (wet and dry) to clean out sumps (smaller). Remember to pull the bag first! LOL.
 

TorontoBuilder

Ultra Member
The best I know of is hydraulic oil it self, could maybe try diesel fuel, would be cheaper then hydraulic oil. Not sure if would work O.K. Don't try to clean filter unless it is only a screen, don't want pieces of filter in system to clean out also. Price of filter/price of machine/pump. Change filter a few times after getting running. Not sure how much oil you are talking about. A filtering system can be set up with own filter and pump/motor to circulate oil to clean if over 20 gal. or more. Again price of oil/price of machine.
New oil, new filters, happy machine, happy happy LOL operator.
New filters? Haha not ever going to get those.

This machine has a permanent filter designed to be cleaned monthly. I suspect they previous owners were not overly fussy about their maintenance schedule.

I think the sump may hold 10-15 gallons at least
 

Dabbler

(John)
This machine has a permanent filter designed to be cleaned monthly.
That is best case. However, newer technology...

Drop a magnet somewhere in the low pressure part of the return loop and a couple in the sump.

take out all the oil, even by disconnecting the hoses to drain them fully. Run a bottle brush in the hoses - not the stainless kind , but soft nylon and see what comes out...

The refill with 'just enough' to keep the hydraulic pump from getting starved. Add more as needed when engaging the functions.Check the colour and look for debris. It may take a couple, of changes.

Consider long term finding a high flow 1 micron filter like they use for 5 or 7HP log splitters, and plumbing it in the suction portion.
 

Bandit

Active Member
Can you direct return oil to a different container with a hose etc. for the first while of operation/flushing of system, or a container of fresh/clean oil piped to pump while used/flushed oil returns to sump. Not sure if filter is on suction side of system or on return side? Any hydraulic cylinders tend to catch participles and hold them, allowing seals/packing to wear away shafts, pistons, and cylinder walls. Is the same oil in the hydraulics lubing the ways etc?
And as Dabbler said, magnets.
 

Aliva

Super User
Where I retired from we had filter carts, just for this purpose. Check this company near Peterborough.
I'm sure there's someone in the GTA that can offer the same. If a cart is not available add some kerosene to the old oil and run the system for 10 minutes then dump the oil and replace with new oil, run again and change the filters
 

Susquatch

Ultra Member
Moderator
Premium Member
I've often blown a bricklayer's string through a line, tied a cloth to it and pulled it through lines to clean them. You can also make a plug and blow it through with compressed air or even hydraulic pressure.

Wish I could be there to watch you put your hands through those little access doors..... The devil in me would want to make a noise like a rattle snake or a predator clattering it's teeth, or a heavy sharp mechanism tripping....
 

TorontoBuilder

Ultra Member
Where I retired from we had filter carts, just for this purpose. Check this company near Peterborough.
I'm sure there's someone in the GTA that can offer the same. If a cart is not available add some kerosene to the old oil and run the system for 10 minutes then dump the oil and replace with new oil, run again and change the filters
I love this. Never knew such a rental tool existed!
 

TorontoBuilder

Ultra Member
Since I'm going to this extent I may just pull the cylinder and replace all the cup seals and spacing rings too.

Great advise from everyone. I have now gone from very hesitant to king of the world confidence regarding the road ahead. I'm sure that's just dunning kruger effect tho
 

DPittman

Ultra Member
Since I'm going to this extent I may just pull the cylinder and replace all the cup seals and spacing rings too.

Great advise from everyone. I have now gone from very hesitant to king of the world confidence regarding the road ahead. I'm sure that's just dunning kruger effect tho
I now have to go Google "dunning kruger" effect. Every time I visit this forum I come away a little bit smarter!:)

All irony on purpose.
 

TorontoBuilder

Ultra Member
I now have to go Google "dunning kruger" effect. Every time I visit this forum I come away a little bit smarter!:)

The Dunning-Kruger effect occurs when a person's lack of knowledge and skills in a certain area cause them to overestimate their own competence.

By contrast, this effect also causes those who excel in a given area to think the task is simple for everyone, and underestimate their relative abilities as well.
 

TorontoBuilder

Ultra Member
Thanks to @Aliva I was able to find out about oil filter carts.... and find a GTA area company that rents such carts.

Their price is more than I'd like to pay at $150 per day, but their filter charges are reasonable at 18 bucks each, AND I can rent from Friday afternoon until Monday morning as a single day and really take my time running and filtering the machine for hours.

York Hydraulics also carries parts so I'm hopeful they can find replacement cup seals for the pistons, and perhaps the inset filter.


My proposed procedure,
  1. Start by performing the following steps:
    • Pull and clean the internal filter.
    • Disconnect the vertical supply pipe from the hydraulic cylinder, starting from below.
    • Remove the box nut from both ends of the cylinder and extract the piston.
    • Remove the spacing rings and cup seals located in the middle of the piston, as well as the cup seals from the ends of the piston.
  2. Next, bring these parts to York Hydraulics to find suitable replacements. If they don't have the required seals, carefully measure and photograph the parts, reinstall them temporarily, and search for replacements later.
  3. Reinstall the new parts, assemble the piston, and insert the filter. Proceed with the cleaning process as follows:
    • Run the hydraulic pump to test if the filter cleaning resolves the overload tripping issue. Assuming it does, run both the hydraulic pump and the filter cart pump for several hours.
    • Pump out the now supposedly cleaner hydraulic fluid into clean 5-gallon pails.
    • Once again, pull out the filter, clean it, and reinstall it.
    • Fill the reservoir with new ISO 22 fluid and run it through the hydraulic system for several hours to further flush everything out. Note that there aren't many components or valves in the system.
  4. Pull the filter once more, clean it, and rinse it with kerosene or varsol. Drain the fluid and refill the system with 48 viscosity hydraulic oil.
Following these steps should complete the procedure.


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