Pre-filtering fluid

[5030tinkerer]

Anyone have any tips on how to pre-filter hydraulic fluid? I've got an old Koehring excavator that requires fresh fluid going into the tank to be filtered through a 10 micron filter. They particularly go out of their way to indicate that brand new fluid is not clean enough. Any ideas on how to go about pre-filtering like this? We're talking 60 gallons of fluid here...

 

[Scooby074]

old Koehring excavator

How old? I wouldnt sweat the pre filtration.

It certainly can be done though. Usually there is a filter cart, with a couple larger hyd filters and a pump. The pump sucks from a bucket of new oil and pushes it through the filters into the tank. You can buy or rig something up, but the carts I know of coast several hundred each.

Its one of those things that sounds good to engineers and manual writers, but in practice is more hassle than its worth. New, high quality oil from a clean bucket, with a clean funnel is fine. I used to dump $250/bucket synth hydraulic oil directly into $750,000 excavators without pre filtering. Cleanliness, particularly around the tank opening, buckets and funnels is more important that pre filtering IMHO. One chunk of dirt falling in the tank when you open the filler will undo $1000 worth of pre-filter cart every time.

 

[Bigfoot62]

Scooby's right. Just buy good fluid.

I get Mobilfluid 424 in 5 gallon buckets from the local Exxon/Mobil jobber.

 

[wdchyd]

I would only be worried about pre-filtration if it comes out of a 55 gal drum......5 gal pails usually are prefiltered and cleaner

 

[firemanmike69]

I absolutely wouldn't even bother with pre-filtering the new oil. Like others said make sure the funnels and cap are free of loose dirt and change the oil

 

[Gary Fowler]

Fluid from 50-70 years ago might not have been very clean, but todays fluids are cleaner than 10 micron filters right out of the can.
As others have said, make sure your equipment tank filler hole, funnels and other filling equipment is clean and don't worry about the oil itself.

 

[5030tinkerer]

The machine is circa 1988 - not THAT old, but old enough from a parts availability perspective, it seems.

A bit more info on the filtering - I just had had a hose burst on this machine a couple weeks ago and lost 50 gallons of fluid. It's a 100 gallon system. I kept the new containers knowing that this service was coming up and drained the main reservoir into the 5 gallon pails yesterday. This is *actually* the main reason for wanting to filter now. In fact, I'd like to run it through a 2 micron filter if at all possible. I may pick up a filter head and spin on 2 micron filter along with a few hoses and mock something up.

 

[Scooby074]

I assume the buckets were clean. The drain hole area was also clean. No Floor Dry in the area (floor dry = bad mojo)

Personally on a excavator that old, assuming you made sure everything was clean prior to dropping the fluid, Id just reuse it without filtering.

You can certainly rig something up to put your mind at ease. Here's a "cheap" cart for some "ideas" 1/2 HP Oil Filter/Transfer Cart | Princess Auto

 

[5030tinkerer]

The buckets and drain hole were clean, yes. Interesting cart! I may have to fab something up. If this were the only machine I had, I wouldn't bother. I have a small fleet, though.

 

[MHarryE]

At Caterpillar - our large cold planers (for milling the asphalt off roadways) had a pre-filter package. Pour the oil into a fill reservoir, then operate a hand pump to filter the oil fine enough to meet all the piston pump and motor requirements. Added expense but worth it on a machine with so many hydrostatic drives. We test cleanliness of every hydraulic system before shipping - if it fails it needs to be attached to a kidney loop machine for extra cleaning.